Spring MVC重定向和轉發及異常處理

本文轉載自查看原文 2017-01-04 21:26 3678 Spring MVC重定向和轉發及異常處理

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。
對於請求轉發的頁面，也可以是WEB-INF中頁面；對於重定向的頁面，不能為WEB-INF中的頁面。因為重定向相當於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.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://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.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://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，並且該類需要在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");
        
        //view
        if(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.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://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

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