json-schema-validator

The java-json-tools/json-schema-validator is a Java library for validating JSON documents against JSON Schema specifications. It supports JSON Schema drafts 4, 6, 7, and 2019-09, providing a robust solution for JSON validation in Java applications.

Pros

• Supports multiple JSON Schema drafts, ensuring compatibility with various schema versions
• Offers extensive validation capabilities, including complex schema structures and custom keywords
• Actively maintained with regular updates and bug fixes
• Well-documented with clear usage instructions and examples

Cons

• Performance may be slower compared to some other JSON Schema validators
• Limited support for the latest JSON Schema draft (2020-12 at the time of writing)
• Dependency on other java-json-tools libraries, which may increase the project's footprint
• Learning curve for advanced features and custom keyword implementations

Code Examples

1. Basic JSON Schema validation:

JsonSchema schema = JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V7).getSchema(schemaJson);
ProcessingReport report = schema.validate(jsonNode);
if (report.isSuccess()) {
    System.out.println("Validation successful");
} else {
    System.out.println("Validation failed: " + report);
}

2. Creating a schema from a file:

JsonNode schemaNode = JsonLoader.fromFile(new File("path/to/schema.json"));
JsonSchema schema = JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V7).getSchema(schemaNode);

3. Custom keyword implementation:

public class CustomKeywordValidator extends KeywordValidator {
    @Override
    public void validate(Processor processor, ProcessingReport report, MessageBundle bundle, JsonNode instance)
            throws ProcessingException {
        // Custom validation logic here
    }
}

// Register the custom keyword
keyword = Keyword.newBuilder("customKeyword").withValidatorClass(CustomKeywordValidator.class).freeze();
JsonSchemaFactory factory = JsonSchemaFactory.builder(JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V7))
        .addKeyword(keyword).freeze();

Getting Started

To use the java-json-tools/json-schema-validator in your project, add the following dependency to your Maven pom.xml:

<dependency>
    <groupId>com.github.java-json-tools</groupId>
    <artifactId>json-schema-validator</artifactId>
    <version>2.2.14</version>
</dependency>

For Gradle, add this to your build.gradle:

implementation 'com.github.java-json-tools:json-schema-validator:2.2.14'

Then, you can start using the library in your Java code as shown in the code examples above.