java - hibernate validator 。如何使用@Valid 注解？

Question

@Valid 注解放在方法参数层的目的是什么？

public void (@Valid Person p) { ... }

我创建了一个测试，并向该方法传递了一个无效对象，但没有任何反应。
我希望得到一个异常(exception)。

Answer 1

对象上的@Valid 注释指示验证框架处理带注释的对象。当用于方法的参数时，这称为方法级别验证。请注意，方法级验证不是核心规范的一部分，实际上只有当 Bean Validation 集成到容器类型框架(JSF、CDI、Java EE ).当 Bean Validation 集成到这样的支持容器中时，会发生这样的情况，即在 bean 上调用生命周期方法时，容器检测方法参数上的 JSR 303 注释并触发关联 bean 的验证。

例如，如果您在 JAX-RS 资源类中有以下方法定义:

@Path("/example")
public class MyExampleResourceImpl {

    @POST
    @Path("/")
    public Response postExample(@Valid final Example example) {
        // ....
    }
}

当 postExample 方法被调用以响应 JAX-RS 容器正在处理的请求时，example bean 将被验证。将此行为与运行独立 Java SE 应用程序时会发生的情况进行对比:

public class MyMainClass {
    public static void main(final String[] args) {
        final MyMainClass clazz = new MyMainClass();
        clazz.echo(new Example());
    }

    public Example echo(@Valid final Example example) {
        // ...
    }
}

在这种情况下，运行该程序将不会触发 Example 参数的验证，即使您包含了所有 JSR 303 运行时 JAR .这是因为没有可用的容器来实现方法级别的验证。 Bean Validation Specification在附录 C 中详细描述了所有这些内容。为了您的方便，我在下面引用了其中的一些内容:

Proposal for method-level validation

This proposition has not been integrated into the core specification and is not part of it. It remains here for archaeological purposes and will be seriously considered for a future revision of this specification. This proposal is likely to be a bit out of sync with the rest of the specification artifacts.

Note: Bean Validation providers are free to implement this proposal as a specific extension. Such specific extension could for example be accessed via the use of the Validator.unwrap method.

A popular demand was to provide a method and parameter level validation mechanism reusing the constraint descriptions of the specification. This set of APIs is meant to be used by interceptor frameworks such as:

• application frameworks like
  • JSR-299
• component frameworks like Enterprise Java Beans
• aspect based frameworks

These frameworks can call the validation APIs to validate either the parameter list or the returned value of a method when such method is called. More precisely, validation occurs around a method invocation. This extension of the Bean Validation API allows to reuse the core engine as well as the constraint definition and declaration for such method level validations.