問題描述

使用 javax.validation.constraints 中的注解(如 @Size、@NotNull 等)需要什么配置?這是我的代碼:

What configuration is needed to use annotations from javax.validation.constraints like @Size, @NotNull, etc.? Here's my code:

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

public class Person {
      @NotNull
      private String id;

      @Size(max = 3)
      private String name;

      private int age;

      public Person(String id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
      }
}

當我嘗試在另一個類中使用它時，驗證不起作用(即對象創建時沒有錯誤):

When I try to use it in another class, validation doesn't work (i.e. the object is created without error):

Person P = new Person(null, "Richard3", 8229));

為什么這不對 id 和 name 應用約束?我還需要做什么?

Why doesn't this apply constraints for id and name? What else do I need to do?

推薦答案

要讓 JSR-303 bean 驗證在 Spring 中工作，您需要做幾件事:

For JSR-303 bean validation to work in Spring, you need several things:

1. 注解的MVC命名空間配置:<mvc:annotation-driven/>
2. JSR-303 規范 JAR:validation-api-1.0.0.GA.jar(看起來你已經有了)
3. 規范的實現，例如 Hibernate Validation，這似乎是最常用的示例:hibernate-validator-4.1.0.Final.jar
4. 在要驗證的 bean 中，驗證注釋，來自規范 JAR 或來自實現 JAR(您已經完成)
5. 在您要驗證的處理程序中，使用@Valid 注釋您要驗證的對象，然后在方法簽名中包含一個BindingResult 以捕獲錯誤.

1. MVC namespace configuration for annotations: <mvc:annotation-driven />
2. The JSR-303 spec JAR: validation-api-1.0.0.GA.jar (looks like you already have that)
3. An implementation of the spec, such as Hibernate Validation, which appears to be the most commonly used example: hibernate-validator-4.1.0.Final.jar
4. In the bean to be validated, validation annotations, either from the spec JAR or from the implementation JAR (which you have already done)
5. In the handler you want to validate, annotate the object you want to validate with @Valid, and then include a BindingResult in the method signature to capture errors.

例子:

@RequestMapping("handler.do")
public String myHandler(@Valid @ModelAttribute("form") SomeFormBean myForm, BindingResult result, Model model) {
    if(result.hasErrors()) {
      ...your error handling...
    } else {
      ...your non-error handling....
    }
}

這篇關于javax.validation.constraints 中的注釋不起作用的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！