AnViL - Annotation Validation Library¶

Anvil is a powerful and type-safe Java validation library for JSON deserialization with annotation-based schema validation. It provides declarative validation rules that ensure your data meets the requirements before it is processed.

Features¶

✨ Declarative Validation - Define validation rules using simple annotations.

🎯 Type-Safe - Full compile-time type checking with Java generics.

🔌 Multiple JSON Processors - Built-in support for Gson and Jackson.

📝 Rich Annotation Set - Comprehensive validation annotations for all common scenarios.

⚡️ Fail-Fast Mode - Stop validation on first error.

🎨 Extensible - Easy to add custom validators and processors.

🔍 Detailed Error Messages - Clear validation errors with field-level granularity.

Why Anvil?¶

• Declarative Validation: Define rules with annotations instead of imperative code.
• Framework Agnostic: Works with Gson, Jackson, or implement your own processor.
• Rich Annotations: Numeric comparisons, string matching, enums, and custom validators.
• Developer Friendly: Clear error messages and fail-fast validation.

Modules¶

Anvil is split into three modules:

• anvil-core - Core annotations and validation framework.
• anvil-processor-gson - Gson processor implementation.
• anvil-processor-jackson - Jackson processor implementation.

Choose the processor that matches your JSON library!

Installation¶

anvil-core¶

<dependency>
    <groupId>io.github.scastd</groupId>
    <artifactId>anvil-core</artifactId>
    <version>0.1.1</version>
</dependency>

implementation 'io.github.scastd:anvil-core:0.1.1'

anvil-processor-gson¶

<dependency>
    <groupId>io.github.scastd</groupId>
    <artifactId>anvil-processor-gson</artifactId>
    <version>0.1.1</version>
</dependency>

implementation 'io.github.scastd:anvil-processor-gson:0.1.1'

anvil-processor-jackson¶

<dependency>
    <groupId>io.github.scastd</groupId>
    <artifactId>anvil-processor-jackson</artifactId>
    <version>0.1.1</version>
</dependency>

implementation 'io.github.scastd:anvil-processor-jackson:0.1.1'

Requirements¶

• Java 21 or higher

Quick Start¶

@Validate
public class User implements Schema {
    private String username;

    @Between(min = 18, max = 120)
    private Integer age;

    @In({"admin", "user", "guest"})
    private String role;
}

Anvil<JsonObject> anvil = new Anvil<>(new GsonProcessor());
User user = anvil.validate(jsonObject, User.class);

Anvil<ObjectNode> anvil = new Anvil<>(new JacksonProcessor());
User user = anvil.validate(objectNode, User.class);

Documentation¶

The full Javadocs are available here.