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Spring MVC重定向和转发及异常处理
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Spring MVC重定向和转发及异常处理
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SpringMVC核心技術---轉發和重定向
當處理器對請求處理完畢后，向其他資源進行跳轉時，有兩種跳轉方式：請求轉發與重定向。而根據要跳轉的資源類型，又可分為兩類：跳轉到頁面與跳轉到其他處理器。
對于請求轉發的頁面，也可以是WEB-INF中頁面；對于重定向的頁面，不能為WEB-INF中的頁面。因為重定向相當于用戶再次發出一次請求，而用戶是不能直接訪問WEB-INF中資源的
?
1）重定向到頁面
?FirstController.java
package cn.controller;import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping;/*** * @author **/ @Controller public class FirstController {@RequestMapping(value="/first.do")public String doAddOrder(Model model,String uname,int uage){model.addAttribute("uname", uname);model.addAttribute("uage",uage);return "redirect:/welcome.jsp";}}?
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><base href="<%=basePath%>"><style type="text/css">form{margin:0px auto;/* border:1px solid red; */width:500px;}</style><title></title></head><body><form action="${pageContext.request.contextPath }/first.do" method="post">姓名:<input name="uname"/><br/><br/>年齡:<input name="uage"/><br/><br/><input type="submit" value="注冊"/></form></body> </html>welcome.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><base href="<%=basePath%>"><title>歡迎頁面</title></head><h1>歡迎訪問${uname }${param.uage }</h1></body> </html>2）重定向到控制器:
FirstController.java
?
package cn.controller;import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping;/*** * @author **/ @Controller public class FirstController {//處理器方法 doFirst==========》doSecond@RequestMapping(value="/first.do")public String doAddOrder(Model model,String uname,int uage){model.addAttribute("uname", uname);model.addAttribute("uage",uage);return "redirect:second.do";}@RequestMapping(value="/second.do")public String doList(Model model,String uname,int uage){model.addAttribute("uname", uname);model.addAttribute("uage",uage);System.out.println(uname+"==================");return "redirect:/welcome.jsp";}}其它與上述相同
?轉發與重定向一樣，就不多做解釋
?
異常處理
描述
在J2EE項目的開發中，不管是對底層的數據庫操作過程，還是業務層的處理過程，還是控制層的處理過程，都不可避免會遇到各種可預知的、不可預知的異常需要處理。每個過程都單獨處理異常，系統的代碼耦合度高，工作量大且不好統一，維護的工作量也很大。?
那么，能不能將所有類型的異常處理從各處理過程解耦出來，這樣既保證了相關處理過程的功能較單一，也實現了異常信息的統一處理和維護？答案是肯定的。下面將介紹使用Spring MVC統一處理異常的解決和實現過程。?
分析
Spring MVC處理異常常見有4種方式：?
?1）使用Spring MVC提供的簡單異常處理器SimpleMappingExceptionResolver?
?2）實現Spring的異常處理SimpleMappingExceptionResolver自定義自己的異常處理器
?3）實現HandlerExceptionResolver 接口自定義異常處理器?
?4）使用注解@ExceptionHandler實現異常處理
我們先介紹三種：
案例
系統異常處理SimpleMappingExceptionResolver
web.xml配置
<?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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 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></display-name><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:applicationContext.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><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list> </web-app>index.jsp頁面
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><base href="<%=basePath%>"><style type="text/css">form{margin:0px auto;background-color:pink;width:500px;}</style><title></title></head><body><h1>系統異常處理</h1><form action="${pageContext.request.contextPath }/first.do" method="post">姓名:<input name="name"/><br/><br/>年齡:<input name="age"/><br/><br/><input type="submit" value="注冊"/></form></body> </html>errors.jsp(報錯是跳轉到此頁面)
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><base href="<%=basePath%>"><title>錯誤頁面</title></head><body><h1>我是所有錯誤消息顯示頁面</h1>${ex.message }</body> </html>MyController.java(定義處理器)
package cn.controller;import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; /*** * @author **/ @Controller public class MyController {//處理器方法@RequestMapping(value="/first.do")public String doFirst(){//構造異常 int result=5/0;return "/WEB-INF/index.jsp";}}applicationContext.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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"><!-- 包掃描器 --><context:component-scan base-package="cn.controller"></context:component-scan><!-- 注冊系統異常處理器 --><bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"><property name="defaultErrorView" value="errors.jsp"></property><property name="exceptionAttribute" value="ex"></property></bean></beans>效果：
?
?
?實現Spring的異常處理接口SimpleMappingExceptionResolver自定義自己的異常處理器
?
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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 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></display-name><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:applicationContext.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><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list> </web-app>error包中是指定錯誤頁面
nameerrors.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><base href="<%=basePath%>"><title>錯誤頁面</title></head><body><h1>用戶名錯誤</h1>${ex.message }</body> </html>ageerrors.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><base href="<%=basePath%>"><title>錯誤頁面</title></head><body><h1>年齡錯誤</h1>${ex.message }</body> </html>FirstController.java
package cn.controller;import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import cn.exceptions.AgeException; import cn.exceptions.NameException; import cn.exceptions.UserInfoException;/*** * @author **/ @Controller public class FirstController {//處理器方法 @RequestMapping(value="/first.do")public String doFirst(String name,int age) throws UserInfoException{if (!"hh".equals(name)) {throw new NameException("用戶名錯誤");}if (age>40) {throw new AgeException("年齡太大");}return "index.jsp";} }exception包下，指定異常類
UserInfoException.java
package cn.exceptions; /*** * @author **/ public class UserInfoException extends Exception{public UserInfoException() {super();// TODO Auto-generated constructor stub}public UserInfoException(String message) {super(message);// TODO Auto-generated constructor stub}}?NameException.java
package cn.exceptions; /*** * @author **/ public class NameException extends UserInfoException{public NameException() {super();// TODO Auto-generated constructor stub}public NameException(String message) {super(message);// TODO Auto-generated constructor stub}}?AgeException.java
package cn.exceptions;/*** * @author **/ public class AgeException extends UserInfoException{public AgeException() {super();// TODO Auto-generated constructor stub}public AgeException(String message) {super(message);// TODO Auto-generated constructor stub}}applicationContext.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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"><!-- 配置包掃描器--><context:component-scan base-package="cn.controller"></context:component-scan><!-- 注冊系統異常處理器 --> <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"><property name="defaultErrorView" value="errors.jsp"></property><property name="exceptionAttribute" value="ex"></property><property name="exceptionMappings"><props><prop key="cn.exceptions.NameException">error/nameerrors.jsp</prop><prop key="cn.exceptions.AgeException">error/ageerrors.jsp</prop></props></property></bean></beans>效果：
?
?
?
?
?實現HandlerExceptionResolver 接口自定義異常處理器?
?使用Springmvc定義好的SimpleMappingExceptionResolver異常處理器，可以實現發生指定異常后的跳轉。但是若要實現在捕獲到指定異常時，執行一些操作的目的，它是完成不了的。此時，就需要自定義異常處理器。自定義異常處理器，需要實現HandlerExceptionResolver接口，并且該類需要在Springmvc配置文件中進行注冊
?
定義自己的異常處理類
?
package cn.resolvers;import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.HandlerExceptionResolver; import org.springframework.web.servlet.ModelAndView;import cn.exceptions.AgeException; import cn.exceptions.NameException;/*** * @author **/ public class MyHandlerExceptionResolver implements HandlerExceptionResolver{public ModelAndView resolveException(HttpServletRequest request,HttpServletResponse response, Object handler, Exception ex) {ModelAndView mv=new ModelAndView();mv.addObject("ex",ex);mv.setViewName("/errors.jsp");//viewif(ex instanceof NameException){mv.setViewName("/error/nameerrors.jsp");}if(ex instanceof AgeException){mv.setViewName("/error/ageerrors.jsp");}return mv;}}applicationContext.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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"><!-- 包掃描器 --><context:component-scan base-package="cn.controller"></context:component-scan><!-- 注冊自定義異常處理器 --><bean class="cn.resolvers.MyHandlerExceptionResolver"/></beans>其它與上述的一樣
轉載于:https://www.cnblogs.com/6zhi/p/6250293.html
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