本文介紹了javax.validation.constraints 中的注釋不起作用的處理方法，對大家解決問題具有一定的參考價值，需要的朋友們下面隨著小編來一起學習吧！
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(chuàng)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:
- 注解的MVC命名空間配置:
<mvc:annotation-driven/> - JSR-303 規(guī)范 JAR:
validation-api-1.0.0.GA.jar(看起來你已經(jīng)有了) - 規(guī)范的實現(xiàn)，例如 Hibernate Validation，這似乎是最常用的示例:
hibernate-validator-4.1.0.Final.jar - 在要驗證的 bean 中，驗證注釋，來自規(guī)范 JAR 或來自實現(xiàn) JAR(您已經(jīng)完成)
- 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.
- MVC namespace configuration for annotations:
<mvc:annotation-driven /> - The JSR-303 spec JAR:
validation-api-1.0.0.GA.jar(looks like you already have that) - 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 - In the bean to be validated, validation annotations, either from the spec JAR or from the implementation JAR (which you have already done)
- In the handler you want to validate, annotate the object you want to validate with
@Valid, and then include aBindingResultin 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....
}
}
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