统一异常处理：HandlerExceptionResolver

SpringExceptionResolver.java

package com.mmall.common;

import com.mmall.exception.PermissionException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/*必须配置被spring管理，全局异常就会被捕捉 -> spring-servlet.xml*/
@Slf4j
public class SpringExceptionResolver implements HandlerExceptionResolver {
    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception e) {
        String url = request.getRequestURL().toString();
        ModelAndView mv;
        String defaultMsg = "System error";
        
        //如何判断请求时页面请求还是数据请求 .json .page
        //要求项目中所有请求json数据，都是用.json结尾
        if (url.endsWith(".json")){
            //区分使用自定义message还是系统message
            if (e instanceof PermissionException){
                JsonData result = JsonData.fail(e.getMessage());
                mv = new ModelAndView("jsonView", result.toMap());//jsonView 对应dispatcher中的bean id
            }else {
                //输出未知的异常
                log.error("-----unknow json exception! url-----" + url,e);
                JsonData result = JsonData.fail(defaultMsg);
                mv = new ModelAndView("jsonView", result.toMap());
            }
        }else if (url.endsWith(".page")){//page页面使用.page结尾
            log.error("-----unknow page exception! url-----" + url,e);
            JsonData result = JsonData.fail(defaultMsg);
            mv = new ModelAndView("exception", result.toMap());//对应exception.jsp
        }else {
            log.error("-----unknow other exception! url-----" + url,e);
            JsonData result = JsonData.fail(defaultMsg);
            mv = new ModelAndView("jsonView", result.toMap());//默认也返回json格式
        }
        return mv;
    }
}

spring-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!--上下文注解-->
    <context:annotation-config />
    <!--启动注解驱动的spring mvc 功能-->
    <mvc:annotation-driven/>
    
    <!--启动包扫描-->
    <context:component-scan base-package="com.mmall.controller" />
    <context:component-scan base-package="com.mmall.service" />


    <!--管理异常处理类 SpringExceptionResolver-->
    <bean class="com.mmall.common.SpringExceptionResolver"/>    
    <!-- RequestMapping bean--><!--需要一个Handler来适配-->
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/>
    <!--处理请求的返回-->
    <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
    <bean id="jsonView" class="org.springframework.web.servlet.view.json.MappingJackson2JsonView" />
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp" />
    </bean>
</beans>