后端开发基础-SpringMVC框架学习-010——异常处理

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异常处理方式

• 利用简单异常处理器

step1. 在配置文件当中，配置简单异常
处理器。

step2. 提供相应的异常处理页面。
注：一般用来处理系统异常。

• 利用 @ExceptionHandler注解。

step1. 写一个异常处理方法。

step2. 提供相应的异常处理页面。

案例演示：

工程案例目录结构

 pom.xml 

<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>com.study</groupId>
  <artifactId>springcase-day06-2</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  
   <dependencies>
  	<dependency>
  		<groupId>org.springframework</groupId>
  		<artifactId>spring-webmvc</artifactId>
  		<version>3.2.8.RELEASE</version>
  	</dependency>
  </dependencies>
</project>

导入Tomcat类库 

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  <display-name>springcase-day06-2</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
  	<servlet-name>springmvc</servlet-name>
  	<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  	<init-param>
  		<param-name>contextConfigLocation</param-name>
  		<param-value>classpath:app.xml</param-value>
  	</init-param>
  	<load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
  	<servlet-name>springmvc</servlet-name>
  	<url-pattern>*.do</url-pattern>
  </servlet-mapping>
</web-app>

app.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:jdbc="http://www.springframework.org/schema/jdbc"  
	xmlns:jee="http://www.springframework.org/schema/jee" 
	xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:aop="http://www.springframework.org/schema/aop" 
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:util="http://www.springframework.org/schema/util"
	xmlns:jpa="http://www.springframework.org/schema/data/jpa"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
		http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
		http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
		http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
		
		<!-- 配置组件扫描 -->
		<context:component-scan base-package="controller"/>
		<!-- 配置mvc注解扫描 -->
		<mvc:annotation-driven/>
		<!-- 
			配置视图解析器：
			负责将视图名解析成真正的视图对象（比如jsp）。
		 -->
		 <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		 	<property name="prefix" value="/WEB-INF/"/>
		 	<property name="suffix" value=".jsp"/>
		 </bean>
		 
		 <!--配置简单异常处理器  -->
		<!--  <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
		 	<property name="exceptionMappings">
		 		<props>
		 			<prop key="java.lang.NumberFormatException">error</prop>
		 			<prop key="java.lang.StringIndexOutOfBoundsException">error0</prop>
		 		</props>
		 	</property>
		 </bean> -->
</beans>

HelloController.java

package controller;

import javax.servlet.http.HttpServletRequest;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class HelloController {
	
	@ExceptionHandler
	/**
	 * 这是一个异常处理方法，要求使用
	 * @ExceptionHandler注解。
	 * @param ex :处理方法抛出的异常。
	 * @return 方法的返回值是视图名。
	 */
	public String exceute(Exception ex,
			HttpServletRequest request){
		 System.out.println("HelloController的execute方法...");
		 
		 if(ex instanceof NumberFormatException){
			 request.setAttribute("msg", "亲，请输入正确的数字");
			 return "error3";
		 }else if(ex instanceof StringIndexOutOfBoundsException){
			 request.setAttribute("msg", "数组越界啦");
			 return "error3";
		 }
		 
		 return "error4";
	}
	

	@RequestMapping("/hello1.do")
	public String hello1(){
		System.out.println("HelloController的hello1方法...");
		String str = "123a";
		Integer.parseInt(str);
		
		return "hello";
	}

	@RequestMapping("/hello2.do")
	public String hello2(){
		System.out.println("HelloController的hello2方法...");
		String str = "abcdefg";
		str.charAt(100);
		
		return "hello";
	}
}

error.jsp

<%@ page contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<title>error</title>
	</head>
	<body style="font-size:30px;">
		请输入正确的数字
	</body>
</html>

error0.jsp

<%@ page contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<title>error</title>
	</head>
	<body style="font-size:30px;">
		数组越界啦
	</body>
</html>

error3.jsp

<%@ page language="java" 
contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Insert title here</title>
</head>
<body style="font-size:30px;">
	${msg}
</body>
</html>

error4.jsp

<%@ page language="java" 
contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Insert title here</title>
</head>
<body style="font-size:30px;">
	系统繁忙，稍后重试。
</body>
</html>

hello.jsp

<h1>Hello,SpringMVC</h1>

启动Tomcat 运行 springcase-day06-2工程，

录入请求http://localhost:8088/springcase-day06-2//hello1.do

录入请求http://localhost:8088/springcase-day06-2//hello2.do