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

在github中查看完整代码

参考

Bean Validation 技术规范特性概述

Validation, Data Binding, and Type Conversion