SpringMVC处理异常

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SpringMVC处理异常

@(SpringMVC)[springmvc, 异常]

SpringMVC处理异常
- SpringMVC单异常处理
  - SpitterController2
  - SpittleNotFoundException
  - MyError
- springMvc架构级别异常处理
  - 案例
    - 自定义异常类
    - 自定义全局异常处理器
    - 错误页面errorjsp
    - 在SpringMVC配置文件中配置
    - 创建异常
    - 测试

SpringMVC单异常处理

SpitterController2

package spittr.web;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.http.HttpStatus;import org.springframework.web.bind.annotation.*;import spittr.Spittle;import spittr.data.SpitterRepository;// 使用RestController，相当于在每个方法上加上了@ResponseBody@RestController@RequestMapping("/spitter2")public class SpitterController2 {    private SpitterRepository spitterRepository;    @Autowired    public SpitterController2(SpitterRepository spitterRepository) {        this.spitterRepository = spitterRepository;    }    @RequestMapping(value = "/{id}", method = RequestMethod.GET)    public Spittle spittleById(@PathVariable long id) {        Spittle spittle = spitterRepository.findOne(id);        if (spittle == null) {            throw new SpittleNotFoundException(id);        }        return spittle;    }    @ExceptionHandler(SpittleNotFoundException.class)    @ResponseStatus(HttpStatus.NOT_FOUND)    public MyError spittleNotFound(SpittleNotFoundException e) {        long spittleId = e.getSpittleId();        return new MyError(4, "Spittle[" + spittleId + "] not found");    }}

SpittleNotFoundException

package spittr.web;/** * Created by Switch on 2017/1/14. */public class SpittleNotFoundException extends RuntimeException {    private long spittleId;    public SpittleNotFoundException(long spittleId) {        this.spittleId = spittleId;    }    public long getSpittleId() {        return spittleId;    }}

MyError

package spittr.web;/** * Created by Switch on 2017/1/14. */public class MyError {    private int code;    private String message;    public MyError(int code, String message) {        this.code = code;        this.message = message;    }    public int getCode() {        return code;    }    public String getMessage() {        return message;    }}

springMvc架构级别异常处理

系统中异常包括两类：预期异常和运行时异常RuntimeException，前者通过捕获异常从而获取异常信息，后者主要通过规范代码开发、测试通过手段减少运行时异常的发生。
系统的dao、service、controller 出现都通过throws Exception 向上抛出，最后由springmvc
前端控制器交由异常处理器进行异常处理，如下图：
SpringMVC异常处理

案例

自定义异常类

package com.pc.ssm.exception;/** * 自定义异常 *  * @author Switch * @data 2017年1月13日 * @version V1.0 */public class CustomException extends Exception {    private static final long serialVersionUID = -665787561868437767L;    // 异常消息    private String message;    public CustomException() {    }    public CustomException(String message) {        this.message = message;    }    public String getMessage() {        return message;    }    public void setMessage(String message) {        this.message = message;    }}

自定义全局异常处理器

package com.pc.ssm.exception;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.HandlerExceptionResolver;import org.springframework.web.servlet.ModelAndView;/** * 自定义全局异常处理器 *  * @author Switch * @data 2017年1月13日 * @version V1.0 */public class CustomGlobalExceptionResolver implements HandlerExceptionResolver {    @Override    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {        ex.printStackTrace();        String msg = "";        if (ex instanceof CustomException) {            msg = ((CustomException) ex).getMessage();        } else {            msg = "系统繁忙，请稍后再试，或与管理员取得联系！";        }        ModelAndView modelAndView = new ModelAndView();        // 添加错误信息        modelAndView.addObject("error", msg);        modelAndView.setViewName("error");        return modelAndView;    }}

错误页面`error.jsp`

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html><html>    <head>        <meta charset="UTF-8">        <title>系统通知</title>    </head>    <body>         <h2>${error}</h2>    </body></html>

在SpringMVC配置文件中配置

    <!-- 配置异常处理器 -->    <bean id="handlerExceptionResolver" class="com.pc.ssm.exception.CustomGlobalExceptionResolver"/>

创建异常

    @RequestMapping("/showEdit")    public String showEdit(@RequestParam(value = "id") String id, Model model) throws Exception {        User user = userService.findById(Integer.parseInt(id));        // 创造个异常        if(user == null) {            throw new CustomException("用户不存在！");        } else if(user.getId() == 1) {            int i = 1 / 0;        }        model.addAttribute("user", user);        return "edit";    }

测试

访问：http://localhost:8080/SpringMVCAdvanced/user/showEdit.action?id=1，出现“系统繁忙，请稍后再试，或与管理员取得联系！”。
访问：http://localhost:8080/SpringMVCAdvanced/user/showEdit.action?id=2，正常访问。
访问：http://localhost:8080/SpringMVCAdvanced/user/showEdit.action?id=1000023，出现“用户不存在！”。

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