SSM-springMVC 异常处理入门

一、异常处理的相关配置

1、异常处理流程

在这里插入图片描述

2、用idea创建maven项目导入坐标

 <properties>
    <spring.version>5.2.2.RELEASE</spring.version>
  </properties>

  <dependencies>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
      <scope>provided</scope>
    </dependency>
   
  </dependencies>

3、工程结构图

在这里插入图片描述

4、springmvc.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
    //<!--    开启spring的注解扫描-->
    <context:component-scan base-package="com.ccsu"/>
    //<!--    配置视图解析器-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        //<!--        前缀-->
        <property name="prefix" value="/WEB-INF/pages/"></property>
        //<!--        后缀-->
        <property name="suffix" value=".jsp"></property>
    </bean>
    //<!--    配置异常处理器-->
    <bean id="sysExceptionResolver" class="com.ccsu.exception.SysExceptionResolver"></bean>
    //<!--    开启springmvc框架注解的支持-->
    <mvc:annotation-driven/>
</beans>

5、编写异常类

package com.ccsu.exception;

/**
 * 自定义异常类
 */
public class SysException extends Exception{

    //存储提示信息
    private String message;

    public SysException(String message) {
        this.message = message;
    }

    @Override
    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

6、编写异常处理器

package com.ccsu.exception;

import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;

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

public class SysExceptionResolver implements HandlerExceptionResolver {

    /**
     *处理异常业务逻辑
     * @param httpServletRequest
     * @param httpServletResponse
     * @param o
     * @param
     * @return
     */
    @Override
    public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception ex) {
        //获取到异常对象
        SysException e = null;
        if(ex instanceof SysException){
            e = (SysException)ex;
        }else{
            e = new SysException("系统正在维护");
        }
        //创建ModelAndView对象
        ModelAndView mv = new ModelAndView();
        mv.addObject("errorMsg",e.getMessage());
        mv.setViewName("error");
        return mv;
    }
}

7、在web.xml中的配置

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>

  <display-name>Archetype Created Web Application</display-name>
 // <!--  配置解决中文乱码的过滤器-->
  <filter>
    <filter-name>characterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>characterEncodingFilter</filter-name>
    <url-pattern>/ *</url-pattern>
  </filter-mapping>

  //<!--  配置前端控制器-->
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    //<!-- 配置初始化参数，用于读取springMVC的配置文件 -->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    //<!--     配置 servlet 的对象的创建时间点：应用加载时创建。
    //取值只能是非 0 正整数，表示启动顺序 -->
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>

8、controller类编写，模拟异常

@Controller
@RequestMapping("/user")
public class UserController {

    @RequestMapping("/testException")
    public String testException() throws SysException {
        System.out.println("testException执行成功");

        //模拟异常
        try{
            int i=1/0;
        }catch(Exception e){
            e.printStackTrace();
            //抛出自定义异常信息
            throw new SysException("查询所有用户出现错误");
        }
        return "success";
    }
}