概述
Spring MVC支持Bean Validation，通过这个验证技术，可以通过注解方式，很方便的对输入参数进行验证，之前使用的校验方式，都是基于Bean对象的，但是在@RequestParam中，没有Bean对象，这样使得校验无法进行，可以通过使用@Validated注解，使得校验可以进行。
校验bean对象
一般校验bean对象，为了可以自动的校验属性，可以通过两步解决：
一、声明对象
package com.github.yongzhizhan.draftbox.model;
import javax.validation.constraints.Size;
/**
* 带验证的对象
* @author zhanyongzhi
*/
public class Foo { private String validString; @Size(min = 1, max = 5) public String getValidString() { return validString; } public void setValidString(final String vValidString) { validString = vValidString; } }二、通过@Valid注解使用对象
@ResponseBody
@RequestMapping(value = "validObject", method = RequestMethod.POST)
@ResponseStatus(HttpStatus.OK)
public String validObject( @RequestBody() @Valid Foo vFoo, BindingResult vBindingResult){ return vFoo.getValidString(); }校验RequestParams
使用校验bean的方式，没有办法校验RequestParam的内容，一般在处理Get请求的时候，会使用下面这样的代码：
@ResponseBody
@RequestMapping(value = "validString", method = RequestMethod.GET)
@ResponseStatus(HttpStatus.OK)
public String validString( @RequestParam(value = "str", defaultValue = "") String vStr){ return vStr; }使用@Valid注解，对RequestParam对应的参数进行注解，是无效的，需要使用@Validated注解来使得验证生效。操作步骤如下：
一、声明错误处理类
package com.github.yongzhizhan.draftbox.controller; import org.springframework.context.annotation.Bean; import org.springframework.http.HttpStatus; import org.springframework.stereotype.Component; import org.springframework.validation.beanvalidation.MethodValidationPostProcessor; import org.springframework.web.bind.annotation.ControllerAdvice; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.bind.annotation.ResponseStatus; import javax.validation.ValidationException; @ControllerAdvice @Component public class GlobalExceptionHandler { @Bean public MethodValidationPostProcessor methodValidationPostProcessor() { return new MethodValidationPostProcessor(); } @ExceptionHandler @ResponseBody @ResponseStatus(HttpStatus.BAD_REQUEST) public String handle(ValidationException exception) { System.out.println("bad request, " + exception.getMessage()); return "bad request, " + exception.getMessage(); } }二、声明@Validated并加上校验注解
package com.github.yongzhizhan.draftbox.controller; import com.github.yongzhizhan.draftbox.model.Foo; import org.springframework.beans.factory.annotation.Value; import org.springframework.http.HttpStatus; import org.springframework.validation.BindingResult; import org.springframework.validation.annotation.Validated; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.bind.annotation.ResponseStatus; import org.springframework.web.bind.annotation.RestController; import javax.validation.Valid; import javax.validation.constraints.Size; @RestController @SuppressWarnings("UnusedDeclaration") @Validated public class IndexController { @ResponseBody @RequestMapping(value = "validString", method = RequestMethod.GET) @ResponseStatus(HttpStatus.OK) public String validString( @RequestParam(value = "str", defaultValue = "") @Size(min = 1, max = 3) String vStr){ return vStr; } }代码
参考
Bean Validation 技术规范特性概述
Validation, Data Binding, and Type Conversion