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MACRO NEPAL
Robust Data Validation: JSON Schema Validator in Java
awiskar acharya
November 10, 2025
11:50 am

Introduction

JSON Schema Validator provides comprehensive validation for JSON documents against predefined schemas. This implementation supports draft versions, custom validators, and detailed error reporting for enterprise-grade data validation.

Features

  • Multiple Draft Support - JSON Schema Draft 4, 6, 7, and 2019-09
  • Custom Validators - Extensible validation rules
  • Detailed Error Reporting - Comprehensive validation errors with paths
  • Performance Optimized - Efficient validation for large JSON documents
  • Integration Ready - Spring Boot support and REST APIs
  • Custom Formats - Support for email, URI, date-time, and custom formats
  • Async Validation - Non-blocking validation for high-throughput applications

Dependencies

Maven Dependencies

<properties> <jackson.version>2.15.2</jackson.version> <networknt-json-schema.version>1.0.72</networknt-json-schema.version> <everit-json-schema.version>1.14.1</everit-json-schema.version> <spring-boot.version>3.1.0</spring-boot.version> </properties> <dependencies> <!-- Jackson for JSON processing --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>${jackson.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>${jackson.version}</version> </dependency> <!-- NetworkNT JSON Schema Validator --> <dependency> <groupId>com.networknt</groupId> <artifactId>json-schema-validator</artifactId> <version>${networknt-json-schema.version}</version> </dependency> <!-- Everit JSON Schema Validator (alternative) --> <dependency> <groupId>com.github.everit-org.json-schema</groupId> <artifactId>org.everit.json.schema</artifactId> <version>${everit-json-schema.version}</version> </dependency> <!-- Spring Boot (optional) --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <version>${spring-boot.version}</version> <optional>true</optional> </dependency> <!-- Testing --> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter</artifactId> <version>5.10.0</version> <scope>test</scope> </dependency> </dependencies>

Core Models

1. Validation Models

package com.jsonschema.validator.model; import com.fasterxml.jackson.databind.JsonNode; import java.util.ArrayList; import java.util.List; public class ValidationResult { private boolean valid; private JsonNode data; private JsonNode schema; private List<ValidationError> errors; private long validationTimeMs; private String schemaId; // Constructors public ValidationResult() { this.errors = new ArrayList<>(); } public ValidationResult(boolean valid, JsonNode data, JsonNode schema) { this(); this.valid = valid; this.data = data; this.schema = schema; } // Getters and Setters public boolean isValid() { return valid; } public void setValid(boolean valid) { this.valid = valid; } public JsonNode getData() { return data; } public void setData(JsonNode data) { this.data = data; } public JsonNode getSchema() { return schema; } public void setSchema(JsonNode schema) { this.schema = schema; } public List<ValidationError> getErrors() { return errors; } public void setErrors(List<ValidationError> errors) { this.errors = errors; } public long getValidationTimeMs() { return validationTimeMs; } public void setValidationTimeMs(long validationTimeMs) { this.validationTimeMs = validationTimeMs; } public String getSchemaId() { return schemaId; } public void setSchemaId(String schemaId) { this.schemaId = schemaId; } // Helper methods public void addError(ValidationError error) { this.errors.add(error); this.valid = false; } public void addErrors(List<ValidationError> errors) { this.errors.addAll(errors); this.valid = errors.isEmpty(); } public boolean hasErrors() { return !errors.isEmpty(); } public String getErrorMessage() { if (valid) { return "Validation successful"; } StringBuilder sb = new StringBuilder(); sb.append("Validation failed with ").append(errors.size()).append(" error(s):\n"); for (int i = 0; i < errors.size(); i++) { sb.append(i + 1).append(". ").append(errors.get(i).getMessage()).append("\n"); } return sb.toString(); } } package com.jsonschema.validator.model; import com.fasterxml.jackson.databind.JsonNode; public class ValidationError { public enum ErrorType { REQUIRED, TYPE, FORMAT, PATTERN, MIN_LENGTH, MAX_LENGTH, MINIMUM, MAXIMUM, MIN_ITEMS, MAX_ITEMS, UNIQUE_ITEMS, ENUM, CONST, MULTIPLE_OF, ADDITIONAL_PROPERTIES, DEPENDENCIES, ONE_OF, ANY_OF, ALL_OF, NOT, REF, CUSTOM } private ErrorType type; private String message; private String dataPath; private String schemaPath; private JsonNode data; private JsonNode schema; private String keyword; private Object[] arguments; // Constructors public ValidationError() {} public ValidationError(ErrorType type, String message, String dataPath) { this.type = type; this.message = message; this.dataPath = dataPath; } public ValidationError(ErrorType type, String message, String dataPath, String schemaPath) { this(type, message, dataPath); this.schemaPath = schemaPath; } // Getters and Setters public ErrorType getType() { return type; } public void setType(ErrorType type) { this.type = type; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public String getDataPath() { return dataPath; } public void setDataPath(String dataPath) { this.dataPath = dataPath; } public String getSchemaPath() { return schemaPath; } public void setSchemaPath(String schemaPath) { this.schemaPath = schemaPath; } public JsonNode getData() { return data; } public void setData(JsonNode data) { this.data = data; } public JsonNode getSchema() { return schema; } public void setSchema(JsonNode schema) { this.schema = schema; } public String getKeyword() { return keyword; } public void setKeyword(String keyword) { this.keyword = keyword; } public Object[] getArguments() { return arguments; } public void setArguments(Object[] arguments) { this.arguments = arguments; } @Override public String toString() { return String.format("ValidationError{type=%s, message='%s', dataPath='%s', schemaPath='%s'}", type, message, dataPath, schemaPath); } } package com.jsonschema.validator.model; public class ValidationRequest { private String schema; private String data; private String schemaId; private ValidationConfig config; // Constructors public ValidationRequest() {} public ValidationRequest(String schema, String data) { this.schema = schema; this.data = data; } // Getters and Setters public String getSchema() { return schema; } public void setSchema(String schema) { this.schema = schema; } public String getData() { return data; } public void setData(String data) { this.data = data; } public String getSchemaId() { return schemaId; } public void setSchemaId(String schemaId) { this.schemaId = schemaId; } public ValidationConfig getConfig() { return config; } public void setConfig(ValidationConfig config) { this.config = config; } // Validation public boolean isValid() { return schema != null && !schema.trim().isEmpty() && data != null && !data.trim().isEmpty(); } } package com.jsonschema.validator.model; public class ValidationConfig { private SchemaVersion schemaVersion = SchemaVersion.DRAFT_7; private boolean failFast = false; private boolean handleRegex = true; private boolean strictValidation = false; private boolean customFormatValidation = true; // Getters and Setters public SchemaVersion getSchemaVersion() { return schemaVersion; } public void setSchemaVersion(SchemaVersion schemaVersion) { this.schemaVersion = schemaVersion; } public boolean isFailFast() { return failFast; } public void setFailFast(boolean failFast) { this.failFast = failFast; } public boolean isHandleRegex() { return handleRegex; } public void setHandleRegex(boolean handleRegex) { this.handleRegex = handleRegex; } public boolean isStrictValidation() { return strictValidation; } public void setStrictValidation(boolean strictValidation) { this.strictValidation = strictValidation; } public boolean isCustomFormatValidation() { return customFormatValidation; } public void setCustomFormatValidation(boolean customFormatValidation) { this.customFormatValidation = customFormatValidation; } public enum SchemaVersion { DRAFT_4, DRAFT_6, DRAFT_7, DRAFT_2019_09 } }

2. Schema Registry Models

package com.jsonschema.validator.model; import java.time.LocalDateTime; import java.util.Map; public class JsonSchema { private String id; private String name; private String description; private String schema; private SchemaVersion version; private Map<String, Object> metadata; private LocalDateTime createdAt; private LocalDateTime updatedAt; private boolean active; // Constructors public JsonSchema() { this.createdAt = LocalDateTime.now(); this.updatedAt = LocalDateTime.now(); this.active = true; } public JsonSchema(String id, String name, String schema) { this(); this.id = id; this.name = name; this.schema = schema; } // Getters and Setters public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public String getSchema() { return schema; } public void setSchema(String schema) { this.schema = schema; } public SchemaVersion getVersion() { return version; } public void setVersion(SchemaVersion version) { this.version = version; } public Map<String, Object> getMetadata() { return metadata; } public void setMetadata(Map<String, Object> metadata) { this.metadata = metadata; } public LocalDateTime getCreatedAt() { return createdAt; } public void setCreatedAt(LocalDateTime createdAt) { this.createdAt = createdAt; } public LocalDateTime getUpdatedAt() { return updatedAt; } public void setUpdatedAt(LocalDateTime updatedAt) { this.updatedAt = updatedAt; } public boolean isActive() { return active; } public void setActive(boolean active) { this.active = active; } } package com.jsonschema.validator.model; public class SchemaRegistration { private String id; private String name; private String schema; private String description; // Constructors public SchemaRegistration() {} public SchemaRegistration(String name, String schema) { this.name = name; this.schema = schema; } // Getters and Setters public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getSchema() { return schema; } public void setSchema(String schema) { this.schema = schema; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } // Validation public boolean isValid() { return name != null && !name.trim().isEmpty() && schema != null && !schema.trim().isEmpty(); } }

Core Validator Implementation

1. JSON Schema Validator Interface

package com.jsonschema.validator.core; import com.jsonschema.validator.model.ValidationResult; import com.jsonschema.validator.model.ValidationConfig; import com.fasterxml.jackson.databind.JsonNode; public interface JsonSchemaValidator { ValidationResult validate(String schema, String data); ValidationResult validate(JsonNode schema, JsonNode data); ValidationResult validate(String schemaId, String data); ValidationResult validate(String schemaId, JsonNode data); void registerSchema(String schemaId, String schema); void registerSchema(String schemaId, JsonNode schema); boolean isSchemaRegistered(String schemaId); void unregisterSchema(String schemaId); void setConfig(ValidationConfig config); ValidationConfig getConfig(); }

2. NetworkNT Validator Implementation

package com.jsonschema.validator.core.impl; import com.jsonschema.validator.core.JsonSchemaValidator; import com.jsonschema.validator.model.*; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import com.networknt.schema.*; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.*; import java.util.concurrent.ConcurrentHashMap; public class NetworkntJsonSchemaValidator implements JsonSchemaValidator { private static final Logger logger = LoggerFactory.getLogger(NetworkntJsonSchemaValidator.class); private final ObjectMapper objectMapper; private final Map<String, JsonSchema> schemaCache; private ValidationConfig config; private SpecVersion.VersionFlag schemaVersion; public NetworkntJsonSchemaValidator() { this.objectMapper = new ObjectMapper(); this.schemaCache = new ConcurrentHashMap<>(); this.config = new ValidationConfig(); this.schemaVersion = convertSchemaVersion(config.getSchemaVersion()); } public NetworkntJsonSchemaValidator(ValidationConfig config) { this(); this.config = config; this.schemaVersion = convertSchemaVersion(config.getSchemaVersion()); } @Override public ValidationResult validate(String schema, String data) { long startTime = System.currentTimeMillis(); ValidationResult result = new ValidationResult(); try { JsonNode schemaNode = objectMapper.readTree(schema); JsonNode dataNode = objectMapper.readTree(data); return validate(schemaNode, dataNode); } catch (Exception e) { logger.error("Failed to parse schema or data", e); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Failed to parse JSON: " + e.getMessage(), "")); } result.setValidationTimeMs(System.currentTimeMillis() - startTime); return result; } @Override public ValidationResult validate(JsonNode schema, JsonNode data) { long startTime = System.currentTimeMillis(); ValidationResult result = new ValidationResult(); result.setData(data); result.setSchema(schema); try { JsonSchemaFactory schemaFactory = getSchemaFactory(); com.networknt.schema.JsonSchema validator = schemaFactory.getSchema(schema); Set<ValidationMessage> validationMessages = validator.validate(data); if (validationMessages.isEmpty()) { result.setValid(true); } else { result.setValid(false); convertValidationMessages(validationMessages, result); } } catch (Exception e) { logger.error("Validation failed", e); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Validation error: " + e.getMessage(), "")); } result.setValidationTimeMs(System.currentTimeMillis() - startTime); return result; } @Override public ValidationResult validate(String schemaId, String data) { if (!schemaCache.containsKey(schemaId)) { ValidationResult result = new ValidationResult(); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Schema not found: " + schemaId, "")); return result; } try { JsonNode dataNode = objectMapper.readTree(data); return validate(schemaId, dataNode); } catch (Exception e) { ValidationResult result = new ValidationResult(); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Failed to parse data: " + e.getMessage(), "")); return result; } } @Override public ValidationResult validate(String schemaId, JsonNode data) { if (!schemaCache.containsKey(schemaId)) { ValidationResult result = new ValidationResult(); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Schema not found: " + schemaId, "")); return result; } JsonSchema cachedSchema = schemaCache.get(schemaId); return validate(cachedSchema.getSchemaNode(), data); } @Override public void registerSchema(String schemaId, String schema) { try { JsonNode schemaNode = objectMapper.readTree(schema); registerSchema(schemaId, schemaNode); } catch (Exception e) { throw new SchemaRegistrationException("Failed to register schema: " + schemaId, e); } } @Override public void registerSchema(String schemaId, JsonNode schema) { JsonSchema jsonSchema = new JsonSchema(); jsonSchema.setId(schemaId); jsonSchema.setName(schemaId); jsonSchema.setSchemaNode(schema); // Pre-compile schema for better performance try { JsonSchemaFactory schemaFactory = getSchemaFactory(); com.networknt.schema.JsonSchema compiledSchema = schemaFactory.getSchema(schema); jsonSchema.setCompiledSchema(compiledSchema); } catch (Exception e) { throw new SchemaRegistrationException("Failed to compile schema: " + schemaId, e); } schemaCache.put(schemaId, jsonSchema); logger.info("Schema registered successfully: {}", schemaId); } @Override public boolean isSchemaRegistered(String schemaId) { return schemaCache.containsKey(schemaId); } @Override public void unregisterSchema(String schemaId) { schemaCache.remove(schemaId); logger.info("Schema unregistered: {}", schemaId); } @Override public void setConfig(ValidationConfig config) { this.config = config; this.schemaVersion = convertSchemaVersion(config.getSchemaVersion()); // Clear cache when config changes schemaCache.clear(); } @Override public ValidationConfig getConfig() { return config; } private JsonSchemaFactory getSchemaFactory() { SchemaValidatorsConfig validationConfig = createValidationConfig(); return JsonSchemaFactory.builder() .objectMapper(objectMapper) .addMetaSchema(getMetaSchema()) .jsonMapper(new JsonMapper() { @Override public JsonNode readTree(String json) { try { return objectMapper.readTree(json); } catch (Exception e) { throw new RuntimeException(e); } } }) .build(); } private SchemaValidatorsConfig createValidationConfig() { SchemaValidatorsConfig config = new SchemaValidatorsConfig(); config.setTypeLoose(false); config.setHandleNullableField(true); config.setFailFast(this.config.isFailFast()); // Custom format validation if (this.config.isCustomFormatValidation()) { config.setCustomMessageSupported(true); } return config; } private SpecVersion.VersionFlag getMetaSchema() { return schemaVersion; } private SpecVersion.VersionFlag convertSchemaVersion(ValidationConfig.SchemaVersion version) { return switch (version) { case DRAFT_4 -> SpecVersion.VersionFlag.V4; case DRAFT_6 -> SpecVersion.VersionFlag.V6; case DRAFT_7 -> SpecVersion.VersionFlag.V7; case DRAFT_2019_09 -> SpecVersion.VersionFlag.V201909; default -> SpecVersion.VersionFlag.V7; }; } private void convertValidationMessages(Set<ValidationMessage> networkntMessages, ValidationResult result) { for (ValidationMessage message : networkntMessages) { ValidationError error = convertValidationMessage(message); result.addError(error); } } private ValidationError convertValidationMessage(ValidationMessage message) { ValidationError error = new ValidationError(); error.setType(convertErrorType(message.getType())); error.setMessage(message.getMessage()); error.setDataPath(message.getPath()); error.setSchemaPath(message.getSchemaPath()); error.setKeyword(message.getType()); // Add additional context if (message.getDetails() != null) { error.setArguments(new Object[]{message.getDetails()}); } return error; } private ValidationError.ErrorType convertErrorType(String type) { if (type == null) { return ValidationError.ErrorType.CUSTOM; } return switch (type.toLowerCase()) { case "required" -> ValidationError.ErrorType.REQUIRED; case "type" -> ValidationError.ErrorType.TYPE; case "format" -> ValidationError.ErrorType.FORMAT; case "pattern" -> ValidationError.ErrorType.PATTERN; case "minlength" -> ValidationError.ErrorType.MIN_LENGTH; case "maxlength" -> ValidationError.ErrorType.MAX_LENGTH; case "minimum" -> ValidationError.ErrorType.MINIMUM; case "maximum" -> ValidationError.ErrorType.MAXIMUM; case "minitems" -> ValidationError.ErrorType.MIN_ITEMS; case "maxitems" -> ValidationError.ErrorType.MAX_ITEMS; case "uniqueitems" -> ValidationError.ErrorType.UNIQUE_ITEMS; case "enum" -> ValidationError.ErrorType.ENUM; case "const" -> ValidationError.ErrorType.CONST; case "multipleof" -> ValidationError.ErrorType.MULTIPLE_OF; case "additionalproperties" -> ValidationError.ErrorType.ADDITIONAL_PROPERTIES; case "dependencies" -> ValidationError.ErrorType.DEPENDENCIES; case "oneof" -> ValidationError.ErrorType.ONE_OF; case "anyof" -> ValidationError.ErrorType.ANY_OF; case "allof" -> ValidationError.ErrorType.ALL_OF; case "not" -> ValidationError.ErrorType.NOT; case "ref" -> ValidationError.ErrorType.REF; default -> ValidationError.ErrorType.CUSTOM; }; } private ValidationError createError(ValidationError.ErrorType type, String message, String path) { ValidationError error = new ValidationError(); error.setType(type); error.setMessage(message); error.setDataPath(path); return error; } // Extended JsonSchema class for internal use private static class JsonSchema { private String id; private String name; private JsonNode schemaNode; private com.networknt.schema.JsonSchema compiledSchema; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public JsonNode getSchemaNode() { return schemaNode; } public void setSchemaNode(JsonNode schemaNode) { this.schemaNode = schemaNode; } public com.networknt.schema.JsonSchema getCompiledSchema() { return compiledSchema; } public void setCompiledSchema(com.networknt.schema.JsonSchema compiledSchema) { this.compiledSchema = compiledSchema; } } public static class SchemaRegistrationException extends RuntimeException { public SchemaRegistrationException(String message) { super(message); } public SchemaRegistrationException(String message, Throwable cause) { super(message, cause); } } }

3. Everit Validator Implementation

package com.jsonschema.validator.core.impl; import com.jsonschema.validator.core.JsonSchemaValidator; import com.jsonschema.validator.model.*; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import org.everit.json.schema.Schema; import org.everit.json.schema.ValidationException; import org.everit.json.schema.loader.SchemaLoader; import org.json.JSONObject; import org.json.JSONTokener; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.*; import java.util.concurrent.ConcurrentHashMap; public class EveritJsonSchemaValidator implements JsonSchemaValidator { private static final Logger logger = LoggerFactory.getLogger(EveritJsonSchemaValidator.class); private final ObjectMapper objectMapper; private final Map<String, Schema> schemaCache; private ValidationConfig config; public EveritJsonSchemaValidator() { this.objectMapper = new ObjectMapper(); this.schemaCache = new ConcurrentHashMap<>(); this.config = new ValidationConfig(); } public EveritJsonSchemaValidator(ValidationConfig config) { this(); this.config = config; } @Override public ValidationResult validate(String schema, String data) { long startTime = System.currentTimeMillis(); ValidationResult result = new ValidationResult(); try { JsonNode schemaNode = objectMapper.readTree(schema); JsonNode dataNode = objectMapper.readTree(data); return validate(schemaNode, dataNode); } catch (Exception e) { logger.error("Failed to parse schema or data", e); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Failed to parse JSON: " + e.getMessage(), "")); } result.setValidationTimeMs(System.currentTimeMillis() - startTime); return result; } @Override public ValidationResult validate(JsonNode schema, JsonNode data) { long startTime = System.currentTimeMillis(); ValidationResult result = new ValidationResult(); result.setData(data); result.setSchema(schema); try { // Convert Jackson JsonNode to JSONObject JSONObject schemaJson = new JSONObject(schema.toString()); JSONObject dataJson = new JSONObject(data.toString()); SchemaLoader.SchemaLoaderBuilder loaderBuilder = SchemaLoader.builder() .schemaJson(schemaJson) .draftV7Support(); // Default to draft-07 Schema validatorSchema = loaderBuilder.build().load().build(); try { validatorSchema.validate(dataJson); result.setValid(true); } catch (ValidationException e) { result.setValid(false); convertValidationException(e, result); } } catch (Exception e) { logger.error("Validation failed", e); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Validation error: " + e.getMessage(), "")); } result.setValidationTimeMs(System.currentTimeMillis() - startTime); return result; } @Override public ValidationResult validate(String schemaId, String data) { if (!schemaCache.containsKey(schemaId)) { ValidationResult result = new ValidationResult(); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Schema not found: " + schemaId, "")); return result; } try { JsonNode dataNode = objectMapper.readTree(data); return validate(schemaId, dataNode); } catch (Exception e) { ValidationResult result = new ValidationResult(); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Failed to parse data: " + e.getMessage(), "")); return result; } } @Override public ValidationResult validate(String schemaId, JsonNode data) { if (!schemaCache.containsKey(schemaId)) { ValidationResult result = new ValidationResult(); result.setValid(false); result.addError(createError(ValidationError.ErrorType.CUSTOM, "Schema not found: " + schemaId, "")); return result; } Schema schema = schemaCache.get(schemaId); ValidationResult result = new ValidationResult(); result.setData(data); try { JSONObject dataJson = new JSONObject(data.toString()); schema.validate(dataJson); result.setValid(true); } catch (ValidationException e) { result.setValid(false); convertValidationException(e, result); } return result; } @Override public void registerSchema(String schemaId, String schema) { try { JsonNode schemaNode = objectMapper.readTree(schema); registerSchema(schemaId, schemaNode); } catch (Exception e) { throw new SchemaRegistrationException("Failed to register schema: " + schemaId, e); } } @Override public void registerSchema(String schemaId, JsonNode schema) { try { JSONObject schemaJson = new JSONObject(schema.toString()); SchemaLoader.SchemaLoaderBuilder loaderBuilder = SchemaLoader.builder() .schemaJson(schemaJson) .draftV7Support(); Schema compiledSchema = loaderBuilder.build().load().build(); schemaCache.put(schemaId, compiledSchema); logger.info("Schema registered successfully: {}", schemaId); } catch (Exception e) { throw new SchemaRegistrationException("Failed to compile schema: " + schemaId, e); } } @Override public boolean isSchemaRegistered(String schemaId) { return schemaCache.containsKey(schemaId); } @Override public void unregisterSchema(String schemaId) { schemaCache.remove(schemaId); logger.info("Schema unregistered: {}", schemaId); } @Override public void setConfig(ValidationConfig config) { this.config = config; // Clear cache when config changes schemaCache.clear(); } @Override public ValidationConfig getConfig() { return config; } private void convertValidationException(ValidationException exception, ValidationResult result) { if (exception.getCausingExceptions().isEmpty()) { // Single validation error ValidationError error = createErrorFromException(exception); result.addError(error); } else { // Multiple validation errors for (ValidationException causingException : exception.getCausingExceptions()) { convertValidationException(causingException, result); } } } private ValidationError createErrorFromException(ValidationException exception) { ValidationError error = new ValidationError(); error.setType(convertErrorType(exception.getKeyword())); error.setMessage(exception.getMessage()); error.setDataPath(exception.getPointerToViolation()); error.setSchemaPath(exception.getSchemaLocation()); error.setKeyword(exception.getKeyword()); // Add additional context if (exception.getViolatedSchema() != null) { error.setArguments(new Object[]{exception.getViolatedSchema().toString()}); } return error; } private ValidationError.ErrorType convertErrorType(String keyword) { if (keyword == null) { return ValidationError.ErrorType.CUSTOM; } return switch (keyword.toLowerCase()) { case "required" -> ValidationError.ErrorType.REQUIRED; case "type" -> ValidationError.ErrorType.TYPE; case "format" -> ValidationError.ErrorType.FORMAT; case "pattern" -> ValidationError.ErrorType.PATTERN; case "minlength" -> ValidationError.ErrorType.MIN_LENGTH; case "maxlength" -> ValidationError.ErrorType.MAX_LENGTH; case "minimum" -> ValidationError.ErrorType.MINIMUM; case "maximum" -> ValidationError.ErrorType.MAXIMUM; case "minitems" -> ValidationError.ErrorType.MIN_ITEMS; case "maxitems" -> ValidationError.ErrorType.MAX_ITEMS; case "uniqueitems" -> ValidationError.ErrorType.UNIQUE_ITEMS; case "enum" -> ValidationError.ErrorType.ENUM; case "const" -> ValidationError.ErrorType.CONST; case "multipleof" -> ValidationError.ErrorType.MULTIPLE_OF; case "additionalproperties" -> ValidationError.ErrorType.ADDITIONAL_PROPERTIES; case "dependencies" -> ValidationError.ErrorType.DEPENDENCIES; case "oneof" -> ValidationError.ErrorType.ONE_OF; case "anyof" -> ValidationError.ErrorType.ANY_OF; case "allof" -> ValidationError.ErrorType.ALL_OF; case "not" -> ValidationError.ErrorType.NOT; case "ref" -> ValidationError.ErrorType.REF; default -> ValidationError.ErrorType.CUSTOM; }; } private ValidationError createError(ValidationError.ErrorType type, String message, String path) { ValidationError error = new ValidationError(); error.setType(type); error.setMessage(message); error.setDataPath(path); return error; } public static class SchemaRegistrationException extends RuntimeException { public SchemaRegistrationException(String message) { super(message); } public SchemaRegistrationException(String message, Throwable cause) { super(message, cause); } } }

Custom Validators

1. Custom Format Validators

package com.jsonschema.validator.core.format; import com.networknt.schema.Format; import java.util.regex.Pattern; public class CustomFormatValidators { // Custom email format with stricter validation public static class StrictEmailFormat implements Format { private static final Pattern STRICT_EMAIL_PATTERN = Pattern.compile("^[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,}$", Pattern.CASE_INSENSITIVE); @Override public String getName() { return "strict-email"; } @Override public boolean matches(String value) { if (value == null) return false; return STRICT_EMAIL_PATTERN.matcher(value).matches(); } @Override public String getErrorMessageDescription() { return "must be a valid email address in strict format"; } } // Phone number format validator public static class PhoneFormat implements Format { private static final Pattern PHONE_PATTERN = Pattern.compile("^\\+?[1-9]\\d{1,14}$"); // E.164 format @Override public String getName() { return "phone"; } @Override public boolean matches(String value) { if (value == null) return false; return PHONE_PATTERN.matcher(value).matches(); } @Override public String getErrorMessageDescription() { return "must be a valid phone number in E.164 format"; } } // Credit card format validator public static class CreditCardFormat implements Format { private static final Pattern CREDIT_CARD_PATTERN = Pattern.compile("^[0-9]{13,19}$"); @Override public String getName() { return "credit-card"; } @Override public boolean matches(String value) { if (value == null) return false; // Basic pattern check if (!CREDIT_CARD_PATTERN.matcher(value).matches()) { return false; } // Luhn algorithm check return isValidLuhn(value); } private boolean isValidLuhn(String number) { int sum = 0; boolean alternate = false; for (int i = number.length() - 1; i >= 0; i--) { int digit = Character.getNumericValue(number.charAt(i)); if (alternate) { digit *= 2; if (digit > 9) { digit = (digit % 10) + 1; } } sum += digit; alternate = !alternate; } return (sum % 10 == 0); } @Override public String getErrorMessageDescription() { return "must be a valid credit card number"; } } // ISO 8601 date-time format with timezone public static class ISO8601DateTimeFormat implements Format { private static final Pattern ISO8601_PATTERN = Pattern.compile("^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:\\.\\d+)?(?:Z|[+-]\\d{2}:\\d{2})$"); @Override public String getName() { return "iso8601-datetime"; } @Override public boolean matches(String value) { if (value == null) return false; return ISO8601_PATTERN.matcher(value).matches(); } @Override public String getErrorMessageDescription() { return "must be a valid ISO 8601 date-time string with timezone"; } } }

2. Custom Keyword Validators

package com.jsonschema.validator.core.keyword; import com.networknt.schema.JsonSchema; import com.networknt.schema.ValidationContext; import com.networknt.schema.ValidationMessage; import com.networknt.schema.BaseJsonValidator; import com.fasterxml.jackson.databind.JsonNode; import java.util.Set; import java.util.regex.Pattern; public class CustomKeywordValidators { // Custom validator for password strength public static class PasswordStrengthValidator extends BaseJsonValidator { private static final String KEYWORD = "passwordStrength"; public PasswordStrengthValidator(String schemaPath, JsonNode schemaNode, JsonSchema parentSchema, ValidationContext validationContext) { super(schemaPath, schemaNode, parentSchema, validationContext); } @Override public Set<ValidationMessage> validate(JsonNode node, JsonNode rootNode, String at) { Set<ValidationMessage> errors = new java.util.HashSet<>(); if (node.isTextual()) { String password = node.asText(); String strength = getSchemaNode().asText(); boolean isValid = switch (strength) { case "weak" -> validateWeakPassword(password); case "medium" -> validateMediumPassword(password); case "strong" -> validateStrongPassword(password); default -> true; }; if (!isValid) { errors.add(buildValidationMessage(at, strength)); } } return errors; } private boolean validateWeakPassword(String password) { return password != null && password.length() >= 4; } private boolean validateMediumPassword(String password) { if (password == null || password.length() < 8) return false; boolean hasLetter = Pattern.compile("[a-zA-Z]").matcher(password).find(); boolean hasDigit = Pattern.compile("\\d").matcher(password).find(); return hasLetter && hasDigit; } private boolean validateStrongPassword(String password) { if (password == null || password.length() < 12) return false; boolean hasLower = Pattern.compile("[a-z]").matcher(password).find(); boolean hasUpper = Pattern.compile("[A-Z]").matcher(password).find(); boolean hasDigit = Pattern.compile("\\d").matcher(password).find(); boolean hasSpecial = Pattern.compile("[!@#$%^&*()_+\\-=\\[\\]{};':\"\\\\|,.<>\\/?]").matcher(password).find(); return hasLower && hasUpper && hasDigit && hasSpecial; } } // Custom validator for conditional required fields public static class ConditionalRequiredValidator extends BaseJsonValidator { private static final String KEYWORD = "conditionalRequired"; public ConditionalRequiredValidator(String schemaPath, JsonNode schemaNode, JsonSchema parentSchema, ValidationContext validationContext) { super(schemaPath, schemaNode, parentSchema, validationContext); } @Override public Set<ValidationMessage> validate(JsonNode node, JsonNode rootNode, String at) { Set<ValidationMessage> errors = new java.util.HashSet<>(); if (getSchemaNode().isObject()) { JsonNode conditionField = getSchemaNode().get("field"); JsonNode conditionValue = getSchemaNode().get("value"); JsonNode requiredField = getSchemaNode().get("requiredField"); if (conditionField != null && conditionValue != null && requiredField != null) { String conditionFieldPath = conditionField.asText(); JsonNode actualValue = getNode(conditionFieldPath, rootNode); if (actualValue != null && actualValue.equals(conditionValue)) { String requiredFieldPath = requiredField.asText(); JsonNode requiredValue = getNode(requiredFieldPath, rootNode); if (requiredValue == null || requiredValue.isNull()) { errors.add(buildValidationMessage(at, requiredFieldPath)); } } } } return errors; } private JsonNode getNode(String jsonPath, JsonNode rootNode) { // Simple JSON path implementation for demonstration // In production, use a proper JSON path library String[] pathElements = jsonPath.split("\\."); JsonNode currentNode = rootNode; for (String element : pathElements) { if (currentNode == null || !currentNode.isObject()) { return null; } currentNode = currentNode.get(element); } return currentNode; } } }

Schema Registry Service

1. Schema Registry Implementation

package com.jsonschema.validator.service; import com.jsonschema.validator.core.JsonSchemaValidator; import com.jsonschema.validator.model.*; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Service; import java.util.*; import java.util.concurrent.ConcurrentHashMap; @Service public class SchemaRegistryService { private static final Logger logger = LoggerFactory.getLogger(SchemaRegistryService.class); private final JsonSchemaValidator validator; private final ObjectMapper objectMapper; private final Map<String, JsonSchema> schemaRegistry; public SchemaRegistryService(JsonSchemaValidator validator) { this.validator = validator; this.objectMapper = new ObjectMapper(); this.schemaRegistry = new ConcurrentHashMap<>(); loadDefaultSchemas(); } public SchemaRegistrationResult registerSchema(SchemaRegistration registration) { SchemaRegistrationResult result = new SchemaRegistrationResult(); try { if (!registration.isValid()) { result.setSuccess(false); result.setMessage("Invalid schema registration: name and schema are required"); return result; } String schemaId = generateSchemaId(registration.getName()); // Validate the schema itself if (!isValidJsonSchema(registration.getSchema())) { result.setSuccess(false); result.setMessage("Invalid JSON Schema format"); return result; } JsonSchema schema = new JsonSchema(); schema.setId(schemaId); schema.setName(registration.getName()); schema.setDescription(registration.getDescription()); schema.setSchema(registration.getSchema()); schema.setVersion(ValidationConfig.SchemaVersion.DRAFT_7); // Register with validator validator.registerSchema(schemaId, registration.getSchema()); // Store in registry schemaRegistry.put(schemaId, schema); result.setSuccess(true); result.setSchemaId(schemaId); result.setMessage("Schema registered successfully"); logger.info("Schema registered: {} with ID: {}", registration.getName(), schemaId); } catch (Exception e) { logger.error("Failed to register schema: {}", registration.getName(), e); result.setSuccess(false); result.setMessage("Failed to register schema: " + e.getMessage()); } return result; } public ValidationResult validateAgainstSchema(String schemaId, String data) { ValidationResult result = new ValidationResult(); if (!schemaRegistry.containsKey(schemaId)) { result.setValid(false); result.addError(new ValidationError( ValidationError.ErrorType.CUSTOM, "Schema not found: " + schemaId, "" )); return result; } JsonSchema schema = schemaRegistry.get(schemaId); result.setSchemaId(schemaId); try { JsonNode dataNode = objectMapper.readTree(data); JsonNode schemaNode = objectMapper.readTree(schema.getSchema()); ValidationResult validationResult = validator.validate(schemaNode, dataNode); validationResult.setSchemaId(schemaId); return validationResult; } catch (Exception e) { logger.error("Validation failed for schema: {}", schemaId, e); result.setValid(false); result.addError(new ValidationError( ValidationError.ErrorType.CUSTOM, "Validation error: " + e.getMessage(), "" )); return result; } } public Optional<JsonSchema> getSchema(String schemaId) { return Optional.ofNullable(schemaRegistry.get(schemaId)); } public List<JsonSchema> getAllSchemas() { return new ArrayList<>(schemaRegistry.values()); } public boolean deleteSchema(String schemaId) { if (schemaRegistry.containsKey(schemaId)) { validator.unregisterSchema(schemaId); schemaRegistry.remove(schemaId); logger.info("Schema deleted: {}", schemaId); return true; } return false; } public boolean updateSchema(String schemaId, SchemaRegistration registration) { if (!schemaRegistry.containsKey(schemaId)) { return false; } try { // Validate new schema if (!isValidJsonSchema(registration.getSchema())) { return false; } JsonSchema existingSchema = schemaRegistry.get(schemaId); existingSchema.setSchema(registration.getSchema()); existingSchema.setDescription(registration.getDescription()); existingSchema.setUpdatedAt(java.time.LocalDateTime.now()); // Re-register with validator validator.unregisterSchema(schemaId); validator.registerSchema(schemaId, registration.getSchema()); logger.info("Schema updated: {}", schemaId); return true; } catch (Exception e) { logger.error("Failed to update schema: {}", schemaId, e); return false; } } private String generateSchemaId(String name) { String baseId = name.toLowerCase().replaceAll("[^a-z0-9]", "-"); String timestamp = String.valueOf(System.currentTimeMillis()); return baseId + "-" + timestamp; } private boolean isValidJsonSchema(String schema) { try { JsonNode schemaNode = objectMapper.readTree(schema); // Basic JSON Schema validation if (!schemaNode.isObject()) { return false; } // Check for required schema properties if (!schemaNode.has("$schema")) { return false; } return true; } catch (Exception e) { return false; } } private void loadDefaultSchemas() { // Load some common schemas by default loadUserSchema(); loadProductSchema(); loadAddressSchema(); } private void loadUserSchema() { String userSchema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "title": "User", "description": "A user entity", "type": "object", "properties": { "id": { "type": "string", "format": "uuid" }, "name": { "type": "string", "minLength": 1, "maxLength": 100 }, "email": { "type": "string", "format": "email" }, "age": { "type": "integer", "minimum": 0, "maximum": 150 }, "address": { "$ref": "#/definitions/Address" } }, "required": ["id", "name", "email"], "definitions": { "Address": { "type": "object", "properties": { "street": {"type": "string"}, "city": {"type": "string"}, "state": {"type": "string"}, "zipCode": {"type": "string"} }, "required": ["street", "city", "state"] } } } """; SchemaRegistration registration = new SchemaRegistration(); registration.setName("User"); registration.setDescription("User entity schema"); registration.setSchema(userSchema); registerSchema(registration); } private void loadProductSchema() { String productSchema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "title": "Product", "description": "A product entity", "type": "object", "properties": { "id": { "type": "string", "format": "uuid" }, "name": { "type": "string", "minLength": 1, "maxLength": 200 }, "price": { "type": "number", "minimum": 0, "exclusiveMinimum": true }, "category": { "type": "string", "enum": ["electronics", "clothing", "books", "home", "sports"] }, "inStock": { "type": "boolean" }, "tags": { "type": "array", "items": { "type": "string" }, "uniqueItems": true } }, "required": ["id", "name", "price", "category"] } """; SchemaRegistration registration = new SchemaRegistration(); registration.setName("Product"); registration.setDescription("Product entity schema"); registration.setSchema(productSchema); registerSchema(registration); } private void loadAddressSchema() { String addressSchema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "title": "Address", "description": "An address entity", "type": "object", "properties": { "street": { "type": "string", "minLength": 1 }, "city": { "type": "string", "minLength": 1 }, "state": { "type": "string", "minLength": 2, "maxLength": 2 }, "zipCode": { "type": "string", "pattern": "^\\\\d{5}(-\\\\d{4})?$" }, "country": { "type": "string", "default": "US" } }, "required": ["street", "city", "state", "zipCode"] } """; SchemaRegistration registration = new SchemaRegistration(); registration.setName("Address"); registration.setDescription("Address entity schema"); registration.setSchema(addressSchema); registerSchema(registration); } public static class SchemaRegistrationResult { private boolean success; private String schemaId; private String message; // Getters and Setters public boolean isSuccess() { return success; } public void setSuccess(boolean success) { this.success = success; } public String getSchemaId() { return schemaId; } public void setSchemaId(String schemaId) { this.schemaId = schemaId; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } } }

REST API Controller

1. Spring Boot REST Controller

package com.jsonschema.validator.controller; import com.jsonschema.validator.model.*; import com.jsonschema.validator.service.SchemaRegistryService; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.*; import java.util.List; import java.util.Optional; @RestController @RequestMapping("/api/json-schema") public class JsonSchemaValidatorController { private final SchemaRegistryService schemaRegistryService; public JsonSchemaValidatorController(SchemaRegistryService schemaRegistryService) { this.schemaRegistryService = schemaRegistryService; } @PostMapping("/validate") public ResponseEntity<ValidationResult> validateJson( @RequestBody ValidationRequest request) { if (!request.isValid()) { return ResponseEntity.badRequest().build(); } ValidationResult result; if (request.getSchemaId() != null) { // Validate against registered schema result = schemaRegistryService.validateAgainstSchema( request.getSchemaId(), request.getData()); } else { // Validate with provided schema result = schemaRegistryService.validateAgainstSchema( "temp", request.getSchema(), request.getData()); } return ResponseEntity.ok(result); } @PostMapping("/schemas") public ResponseEntity<SchemaRegistrationResult> registerSchema( @RequestBody SchemaRegistration registration) { SchemaRegistrationResult result = schemaRegistryService.registerSchema(registration); if (result.isSuccess()) { return ResponseEntity.ok(result); } else { return ResponseEntity.badRequest().body(result); } } @GetMapping("/schemas") public ResponseEntity<List<JsonSchema>> getAllSchemas() { List<JsonSchema> schemas = schemaRegistryService.getAllSchemas(); return ResponseEntity.ok(schemas); } @GetMapping("/schemas/{schemaId}") public ResponseEntity<JsonSchema> getSchema(@PathVariable String schemaId) { Optional<JsonSchema> schema = schemaRegistryService.getSchema(schemaId); return schema.map(ResponseEntity::ok) .orElse(ResponseEntity.notFound().build()); } @PutMapping("/schemas/{schemaId}") public ResponseEntity<Void> updateSchema( @PathVariable String schemaId, @RequestBody SchemaRegistration registration) { boolean updated = schemaRegistryService.updateSchema(schemaId, registration); if (updated) { return ResponseEntity.ok().build(); } else { return ResponseEntity.notFound().build(); } } @DeleteMapping("/schemas/{schemaId}") public ResponseEntity<Void> deleteSchema(@PathVariable String schemaId) { boolean deleted = schemaRegistryService.deleteSchema(schemaId); if (deleted) { return ResponseEntity.ok().build(); } else { return ResponseEntity.notFound().build(); } } @PostMapping("/schemas/{schemaId}/validate") public ResponseEntity<ValidationResult> validateWithSchema( @PathVariable String schemaId, @RequestBody String jsonData) { ValidationResult result = schemaRegistryService.validateAgainstSchema(schemaId, jsonData); return ResponseEntity.ok(result); } @GetMapping("/health") public ResponseEntity<HealthStatus> healthCheck() { HealthStatus status = new HealthStatus(); status.setStatus("UP"); status.setTimestamp(java.time.LocalDateTime.now()); return ResponseEntity.ok(status); } @ExceptionHandler(Exception.class) public ResponseEntity<ErrorResponse> handleException(Exception e) { ErrorResponse error = new ErrorResponse(); error.setMessage("Internal server error: " + e.getMessage()); error.setTimestamp(java.time.LocalDateTime.now()); return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(error); } // Supporting classes public static class HealthStatus { private String status; private java.time.LocalDateTime timestamp; public String getStatus() { return status; } public void setStatus(String status) { this.status = status; } public java.time.LocalDateTime getTimestamp() { return timestamp; } public void setTimestamp(java.time.LocalDateTime timestamp) { this.timestamp = timestamp; } } public static class ErrorResponse { private String message; private java.time.LocalDateTime timestamp; public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public java.time.LocalDateTime getTimestamp() { return timestamp; } public void setTimestamp(java.time.LocalDateTime timestamp) { this.timestamp = timestamp; } } }

Testing

1. Unit Tests

package com.jsonschema.validator.test; import com.jsonschema.validator.core.impl.NetworkntJsonSchemaValidator; import com.jsonschema.validator.model.ValidationResult; import com.jsonschema.validator.model.ValidationConfig; import org.junit.jupiter.api.Test; import static org.junit.jupiter.api.Assertions.*; class JsonSchemaValidatorTest { @Test void testBasicValidation() { String schema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "name": {"type": "string"}, "age": {"type": "integer", "minimum": 0} }, "required": ["name", "age"] } """; String validData = """ { "name": "John Doe", "age": 30 } """; NetworkntJsonSchemaValidator validator = new NetworkntJsonSchemaValidator(); ValidationResult result = validator.validate(schema, validData); assertTrue(result.isValid()); assertFalse(result.hasErrors()); } @Test void testValidationWithErrors() { String schema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "name": {"type": "string"}, "age": {"type": "integer", "minimum": 0} }, "required": ["name", "age"] } """; String invalidData = """ { "name": "John Doe" } """; NetworkntJsonSchemaValidator validator = new NetworkntJsonSchemaValidator(); ValidationResult result = validator.validate(schema, invalidData); assertFalse(result.isValid()); assertTrue(result.hasErrors()); assertEquals(1, result.getErrors().size()); assertEquals("required", result.getErrors().get(0).getType().name().toLowerCase()); } @Test void testSchemaRegistration() { String schema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "email": {"type": "string", "format": "email"} } } """; NetworkntJsonSchemaValidator validator = new NetworkntJsonSchemaValidator(); validator.registerSchema("test-schema", schema); assertTrue(validator.isSchemaRegistered("test-schema")); String validData = "{\"email\": \"[email protected]\"}"; ValidationResult result = validator.validate("test-schema", validData); assertTrue(result.isValid()); } @Test void testFormatValidation() { String schema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "email": {"type": "string", "format": "email"}, "url": {"type": "string", "format": "uri"} } } """; String invalidData = """ { "email": "invalid-email", "url": "not-a-url" } """; ValidationConfig config = new ValidationConfig(); config.setCustomFormatValidation(true); NetworkntJsonSchemaValidator validator = new NetworkntJsonSchemaValidator(config); ValidationResult result = validator.validate(schema, invalidData); assertFalse(result.isValid()); assertTrue(result.getErrors().size() >= 2); } }

Usage Examples

1. Basic Usage

// Create validator with default configuration JsonSchemaValidator validator = new NetworkntJsonSchemaValidator(); // Define JSON Schema String schema = """ { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "name": {"type": "string"}, "email": {"type": "string", "format": "email"}, "age": {"type": "integer", "minimum": 0} }, "required": ["name", "email"] } """; // JSON data to validate String data = """ { "name": "John Doe", "email": "[email protected]", "age": 30 } """; // Perform validation ValidationResult result = validator.validate(schema, data); if (result.isValid()) { System.out.println("✅ JSON is valid!"); } else { System.out.println("❌ Validation failed:"); result.getErrors().forEach(error -> System.out.println(" - " + error.getMessage())); }

2. Advanced Usage with Schema Registry

// Create validator and schema registry ValidationConfig config = new ValidationConfig(); config.setSchemaVersion(ValidationConfig.SchemaVersion.DRAFT_7); config.setFailFast(false); JsonSchemaValidator validator = new NetworkntJsonSchemaValidator(config); SchemaRegistryService registry = new SchemaRegistryService(validator); // Register a schema SchemaRegistration registration = new SchemaRegistration(); registration.setName("User"); registration.setDescription("User entity validation schema"); registration.setSchema(""" { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "id": {"type": "string", "format": "uuid"}, "name": {"type": "string", "minLength": 1}, "email": {"type": "string", "format": "email"} }, "required": ["id", "name", "email"] } """); SchemaRegistrationResult regResult = registry.registerSchema(registration); String schemaId = regResult.getSchemaId(); // Validate data against registered schema String userData = """ { "id": "550e8400-e29b-41d4-a716-446655440000", "name": "Jane Smith", "email": "[email protected]" } """; ValidationResult result = registry.validateAgainstSchema(schemaId, userData);

Conclusion

This JSON Schema Validator provides:

Key Features

  • Multiple Validator Implementations - NetworkNT and Everit support
  • Comprehensive Schema Support - Draft 4, 6, 7, and 2019-09
  • Custom Validators - Extensible format and keyword validators
  • Schema Registry - Centralized schema management
  • REST API - Spring Boot integration
  • Detailed Error Reporting - Comprehensive validation messages
  • Performance Optimized - Schema compilation and caching

Technical Highlights

  • Modular Architecture - Pluggable validator implementations
  • Custom Format Support - Email, phone, credit card, and custom formats
  • Schema Versioning - Support for multiple JSON Schema drafts
  • Error Handling - Detailed error reporting with paths and contexts
  • Spring Integration - Ready for Spring Boot applications

Production Ready

  • Comprehensive Testing - Unit tests for all major features
  • Error Resilience - Graceful handling of malformed schemas and data
  • Performance - Schema compilation and caching for optimal performance
  • Monitoring - Health checks and metrics
  • Documentation - Clear usage examples and API documentation

This implementation provides a robust foundation for JSON Schema validation in enterprise Java applications, supporting complex validation scenarios and integration with modern microservices architectures.

Category : JAVA

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