（五）SpringBoot如何定义全局异常

一：添加业务类异常

创建ServiceException

package com.example.demo.core.ret;

import java.io.Serializable;

/**
 * @Description: 业务类异常
 * @author
 * @date 2018/4/20 14:30
 *
 */
public class ServiceException extends RuntimeException implements Serializable{

   private static final long serialVersionUID = 1213855733833039552L;

   public ServiceException() {
   }

   public ServiceException(String message) {
      super(message);
   }

   public ServiceException(String message, Throwable cause) {
      super(message, cause);
   }
}

　　

三：添加异常处理配置

在上篇讲过的创建的WebConfigurer.java类中，实现如下方法

@Override
public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
    exceptionResolvers.add(getHandlerExceptionResolver());
}

/**
 * 创建异常处理
 * @return
 */
private HandlerExceptionResolver getHandlerExceptionResolver(){
    HandlerExceptionResolver handlerExceptionResolver = new HandlerExceptionResolver(){
        @Override
        public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response,
                                             Object handler, Exception e) {
            RetResult<Object> result = getResuleByHeandleException(request, handler, e);
            responseResult(response, result);
            return new ModelAndView();
        }
    };
    return handlerExceptionResolver;
}

/**
 * 根据异常类型确定返回数据
 * @param request
 * @param handler
 * @param e
 * @return
 */
private RetResult<Object> getResuleByHeandleException(HttpServletRequest request, Object handler, Exception e){
    RetResult<Object> result = new RetResult<>();
    if (e instanceof ServiceException) {
        result.setCode(RetCode.FAIL).setMsg(e.getMessage()).setData(null);
        return result;
    }
    if (e instanceof NoHandlerFoundException) {
        result.setCode(RetCode.NOT_FOUND).setMsg("接口 [" + request.getRequestURI() + "] 不存在");
        return result;
    }
    result.setCode(RetCode.INTERNAL_SERVER_ERROR).setMsg("接口 [" + request.getRequestURI() + "] 内部错误，请联系管理员");
    String message;
    if (handler instanceof HandlerMethod) {
        HandlerMethod handlerMethod = (HandlerMethod) handler;
        message = String.format("接口 [%s] 出现异常，方法：%s.%s，异常摘要：%s", request.getRequestURI(),
                handlerMethod.getBean().getClass().getName(), handlerMethod.getMethod() .getName(), e.getMessage());
    } else {
        message = e.getMessage();
    }
    LOGGER.error(message, e);
    return result;
}

/**
 * @Title: responseResult
 * @Description: 响应结果
 * @param response
 * @param result
 * @Reutrn void
 */
private void responseResult(HttpServletResponse response, RetResult<Object> result) {
    response.setCharacterEncoding("UTF-8");
    response.setHeader("Content-type", "application/json;charset=UTF-8");
    response.setStatus(200);
    try {
        response.getWriter().write(JSON.toJSONString(result,SerializerFeature.WriteMapNullValue));
    } catch (IOException ex) {
        LOGGER.error(ex.getMessage());
    }
}

　　

四：添加配置文件

在 application.properties 中添加两个配置:

spring.mvc.throw-exception-if-no-handler-found=true 

spring.resources.add-mappings=false

　第一个spring.mvc.throw-exception-if-no-handler-found 告诉 SpringBoot 当出现 404 错误时, 直接抛出异常.

  第二个 spring.resources.add-mappings 告诉 SpringBoot 不要为我们工程中的资源文件建立映射.

五：创建测试接口

package com.example.demo.service.impl;

import com.example.demo.core.ret.ServiceException;
import com.example.demo.dao.UserInfoMapper;
import com.example.demo.model.UserInfo;
import com.example.demo.service.UserInfoService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author
 * @Description:
 * @time 2018/4/18 11:56
 */
@Service
public class UserInfoServiceImpl implements UserInfoService{

    @Resource
    private UserInfoMapper userInfoMapper;

    @Override
    public UserInfo selectById(Integer id){
        UserInfo userInfo = userInfoMapper.selectById(id);
        if(userInfo == null){
            throw new ServiceException("暂无该用户");
        }
        return userInfo;
    }
}

　　结果

{
    "code": 500,
    "data": null,
    "msg": "接口 [/userInfo/testException] 内部错误，请联系管理员"
}