java架构之路-（SpringMVC篇）SpringMVC主要流程源码解析（下）注解配置，统一错误处理和拦截器

2019 年 10 月 8 日
笔记

　　我们上次大致说完了执行流程，也只是说了大致的过程，还有中间会出错的情况我们来处理一下。

统一异常处理

比如我们的运行时异常的500错误。我们来自定义一个类

package com.springmvcbk.utils;    import org.springframework.web.servlet.HandlerExceptionResolver;  import org.springframework.web.servlet.ModelAndView;  import javax.servlet.http.HttpServletRequest;  import javax.servlet.http.HttpServletResponse;  import java.io.ByteArrayOutputStream;  import java.io.PrintStream;    public class MyExceptionResolver implements HandlerExceptionResolver {        public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {          ModelAndView mv = new ModelAndView();          mv.setViewName("/WEB-INF/page/error.jsp");          if (ex instanceof IllegalAccessException){              mv.addObject("erroeType","非法参数");          }else{              mv.addObject("erroeType",ex.getClass().getSimpleName());          }          mv.addObject("message",ex.getMessage());          ByteArrayOutputStream bo = new ByteArrayOutputStream();          ex.printStackTrace(new PrintStream(bo,true));          mv.addObject("stack",bo.toString());          return mv;      }  }

将我们的类注入到我们的spring-mvc.xml内

<bean class="com.springmvcbk.utils.MyExceptionResolver"/>

我们让我们的代码运行时异常就可以跳转到我们的error页面上去了。

拦截器

　　还有我们常用的拦截器，也就是我们拿到的HandlerInterceptor来处理拦截的。

package com.springmvcbk.utils;    import org.springframework.web.servlet.HandlerInterceptor;  import org.springframework.web.servlet.ModelAndView;  import javax.servlet.http.HttpServletRequest;  import javax.servlet.http.HttpServletResponse;    public class MyInterceptor implements HandlerInterceptor {        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {          System.out.println("preHandle");          return true;      }        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {          System.out.println("postHandle");      }        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {          System.out.println("afterCompletion");      }  }

<mvc:interceptors>      <mvc:interceptor>          <mvc:mapping path="/**"/>          <bean class="com.springmvcbk.utils.MyInterceptor"/>      </mvc:interceptor>  </mvc:interceptors>

配置我们的拦截范围也就可以了。如果执行过程出现错误就不会执行postHandle了。

还有最后一项，我们最熟悉的@RequestMapping注解的形式，我们还是先来一个最精简的启动

package com.springmvcbk.controller;    import org.springframework.stereotype.Controller;  import org.springframework.web.bind.annotation.RequestMapping;  import org.springframework.web.servlet.ModelAndView;  import javax.servlet.http.HttpServletRequest;  import javax.servlet.http.HttpServletResponse;    @Controller  public class SpringmvController {        @RequestMapping(value = "zhangsan")      public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {          ModelAndView modelAndView = new ModelAndView();          modelAndView.setViewName("/WEB-INF/page/index.jsp");          modelAndView.addObject("name","张三");          return modelAndView;      }  }

<?xml version="1.0" encoding="GBK"?>  <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">        <context:component-scan base-package="com.springmvcbk.controller"/>      <mvc:annotation-driven/>  </beans>

还有我们上次忘记的一个配置，每次返回都要写全路径，累死了，我们在spring-mvc.xml加入这样的配置

 <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">   　　<property name="prefix" value="WEB-INF/page/"/>   　　<property name="suffix" value=".jsp"/>      <property name="viewClass" value="org.springframework.web.servlet.view.InternalResourceView"/>  </bean>