在Spring MVC中使用注解的方式校验RequestParams

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;
    }
}