SpringMVC异常处理

package cn.itcast.controller;

import cn.itcast.service.DemoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.io.FileNotFoundException;

@Controller
public class DemoController {

    @Autowired
    DemoService demoService;

    @RequestMapping("/cast")
    @ResponseBody
    public void cast(){
        demoService.cast();
    }

    @RequestMapping("/nullPointer")
    @ResponseBody
    public void nullPointer(){
        demoService.nullPointer();
    }

    @RequestMapping("/io")
    @ResponseBody
    public void io() throws FileNotFoundException {
        demoService.io();
    }

    @RequestMapping("/zero")
    @ResponseBody
    public void zero(){
        demoService.zero();
    }
}

package cn.itcast.service;

import org.springframework.stereotype.Service;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

@Service
public class DemoService {

    public void cast(){
        String s = (String) new Object();
    }

    public void nullPointer(){
        String s = null;
        s.equals("");
    }

    public void io() throws FileNotFoundException {
        new FileInputStream("d:/x1/x2/x3");
    }

    public void zero(){
        int i = 1 / 0;
    }
}

package cn.itcast.exception;

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.FileNotFoundException;

public class MyExceptionResolver implements HandlerExceptionResolver {
    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
        ModelAndView modelAndView = new ModelAndView();
        if(ex instanceof FileNotFoundException){
            //对文件不存在异常进行特殊处理
            modelAndView.setViewName("noFile");
        }else if(ex instanceof  NullPointerException){
            //对空指针异常进行特殊处理
            modelAndView.setViewName("nullPointer");
        }else{
            //其他的异常，默认处理
            modelAndView.setViewName("error");
        }
        return modelAndView;
    }
}

<?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
">

    <!--组件扫描-->
    <context:component-scan base-package="cn.itcast"></context:component-scan>

    <!--注解驱动-->
    <mvc:annotation-driven></mvc:annotation-driven>

    <!--静态资源处理-->
    <mvc:default-servlet-handler></mvc:default-servlet-handler>

    <!--视图解析前后缀-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

    <!--在SpringMVC中定义多个异常处理器的话，貌似只加载第1个。-->
    <bean class="cn.itcast.exception.MyExceptionResolver"></bean>

    <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <!--定义默认的异常处理页面，所有不在exceptionMappings中的异常，将由这个处理-->
        <property name="defaultErrorView" value="error"></property>
        <!--定义异常处理页面用来获取异常信息的变量名，默认为exception-->
        <property name="exceptionAttribute" value="ex"></property>
        <!--需要特殊处理的异常，key是异常的全类名，value是异常页面-->
        <property name="exceptionMappings">
            <map>
                <entry key="java.io.FileNotFoundException" value="noFile"></entry>
                <entry key="java.lang.ArithmeticException" value="zero"></entry>
            </map>
        </property>
    </bean>

</beans>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <!--spring容器监听器-->
<!--    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>-->


    <!--springmvc前端控制器-->
    <servlet>
        <servlet-name>app</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>app</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>


    <!--编码过滤-->
    <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>

</web-app>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    出错啦！！${ex}
</body>
</html>

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.itcast</groupId>
    <artifactId>spring_mvc_exception</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.0.5.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <!--编译插件-->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <!--tomcat插件-->
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <!-- tomcat7的插件， 不同tomcat版本这个也不一样 -->
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                    <!-- 通过maven tomcat7:run运行项目时，访问项目的端口号 -->
                    <port>80</port>
                    <!-- 项目访问路径  本例：localhost:9090,  如果配置的aa， 则访问路径为localhost:9090/aa-->
                    <path>/</path>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>