BindingResult，MessageSource与@Valid实现接口封装

        程序级别接口返回值，异常和Error通常需要统一编码，本文以项目应用为前提，应用Spring中集成的MessageSource实现国际化，并应用BingdingResult和@Valid实现属性统一校验。实现步骤如下：

       1. 根据约定建立messages.properties，与application.properties同级。

responseMsg.map.0=success

responseMsg.map.1100=server internal exception
responseMsg.map.1101=NoNodeAvailableException
responseMsg.map.1102=IllegalStateException

        2. 建立统一返回Json样式类ResponseJson：

package com.springcloude.common.message;


import com.springcloude.common.plugin.Page;

import java.io.Serializable;

/**
 * @author whp
 * @create 2017-07-21 上午10:14
 */
public class ResponseJson implements Serializable {

  public static final int SUCCESS = 0;
  private static final long serialVersionUID = 1L;
  private int code = 1100;
  private String msg;
  private Object data = null;
  private long currentPage;
  private long totalPage;
  private long totalResults;
  private long currentTotalResults;

  public ResponseJson() {
  }

  public ResponseJson(int code, String msg) {
    this.code = code;
    this.msg = msg;
  }

  public ResponseJson(int code, String msg, Object data) {
    this.code = code;
    this.msg = msg;
    this.data = data;
  }

  public ResponseJson(int code, String msg, Object data, Page page) {
    this.code = code;
    this.msg = msg;
    this.data = data;
    this.totalPage = page.getTotalPage();
    this.currentPage = page.getCurrentPage();
    this.totalResults = page.getCurrentTotalResults();
    this.currentTotalResults=page.getTotalResults();
  }


  public int getCode() {
    return code;
  }

  public void setCode(int code) {
    this.code = code;
  }

  public String getMsg() {
    return msg;
  }

  public void setMsg(String emsg) {
    this.msg = emsg;
  }

  public Object getData() {
    return data;
  }

  public long getCurrentTotalResults() {
    return currentTotalResults;
  }

  public void setCurrentTotalResults(long currentTotalResults) {
    currentTotalResults = currentTotalResults;
  }

  public void setData(Object data) {
    this.data = data;
  }

  public long getCurrentPage() {
    return currentPage;
  }

  public void setCurrentPage(long currentPage) {
    this.currentPage = currentPage;
  }

  public long getTotalPage() {
    return totalPage;
  }

  public void setTotalPage(long totalPage) {
    this.totalPage = totalPage;
  }

  public long getTotalResults() {
    return totalResults;
  }

  public void setTotalResults(long totalResults) {
    this.totalResults = totalResults;
  }

  public void setTotalResults(int totalResults) {
    this.totalResults = totalResults;
  }

}

       3. 建立Controller父类，统一控制输出内容：

package com.springcloud.server1.controller.base;

import com.springcloude.common.message.ResponseJson;
import com.springcloude.common.message.ResponseOAJson;
import com.springcloude.common.plugin.Page;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.context.i18n.LocaleContextHolder;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;

import java.util.ArrayList;
import java.util.List;
import java.util.Locale;


public class BaseController {

  @Autowired
  private MessageSource messageSource;

  protected Logger logger = LoggerFactory.getLogger(BaseController.class);

  public ResponseJson responseMsg(int code) {
    return new ResponseJson(code, MSG(code));
  }

  public ResponseJson responseMsg(int code, String msg) {
    return new ResponseJson(code, msg);
  }

  public ResponseOAJson responseOAJson(int msgCode, String msg){
    return new ResponseOAJson(msgCode,msg);
  }

  public ResponseJson responseMsg(int code, Object data) {
    return new ResponseJson(code, MSG(code), data);
  }

  public ResponseJson responseMsg(int code, Object data, Page page) {
    return new ResponseJson(code, MSG(code), data,page);
  }

  /**
   * 根据错误码，返回messages文件中描述信息
   */
  public String MSG(int key) {
    Locale currentLocale = LocaleContextHolder.getLocale();
    return messageSource.getMessage("responseMsg.map." + key, null, currentLocale);
  }

  /**
   * 实体校验跳转到错误页面
   */
  public String showErrorPage(Model model, BindingResult result) {
    List list = result.getFieldErrors();
    List errors = new ArrayList();
    for (int i = 0; i < list.size(); i++) {
      FieldError fieldError = list.get(i);
      errors.add(fieldError.getField() + ":" + fieldError.getDefaultMessage());
    }

    model.addAttribute("errors", errors);
    return "error_message";
  }

  /**
   * 字段校验失败统一编码为1016
   */
  public ResponseJson showErrorJson(BindingResult result) {
    FieldError error = result.getFieldErrors().get(0);
    return new ResponseJson(1016, error.getField() + ":" + error.getDefaultMessage());
  }
}

     4. 举例应用：

    @RequestMapping(value = "/update",method = RequestMethod.POST)
    public ResponseJson update(@Valid User user,BindingResult result,HttpServletRequest request){
        if(result.hasErrors()){
            return showErrorJson(result);
        }
        int flag=userService.update(user);
        return responseMsg(0,user);
    }

         该实例使用@Valid对User实体进行注解，user配置用户名校验格式：

@NotNull
@Size(min = 1, max = 100)
private String name;

         请求该接口，返回值为：

{
    "code": 1016,
    "msg": "name:不能为null",
    "data": null,
    "currentPage": 0,
    "totalPage": 0,
    "totalResults": 0,
    "currentTotalResults": 0
}