标签:encoding eth att nat gets display init 目的 pack
1 描述
在J2EE项目的开发中,不管是对底层的数据库操作过程,还是业务层的处理过程,还是控制层的处理过程,都不可避免会遇到各种可预知的、不可预知的异常需要处理。每个过程都单独处理异常,系统的代码耦合度高,工作量大且不好统一,维护的工作量也很大。
那么,能不能将所有类型的异常处理从各处理过程解耦出来,这样既保证了相关处理过程的功能较单一,也实现了异常信息的统一处理和维护?答案是肯定的。下面将介绍使用Spring MVC统一处理异常的解决和实现过程。
2 分析
Spring MVC处理异常有3种方式:
(1)使用Spring MVC提供的简单异常处理器SimpleMappingExceptionResolver;
(2)实现Spring的异常处理SimpleMappingExceptionResolver自定义自己的异常处理器;
(3)实现HandlerExceptionResolver 接口自定义异常处理器
(4)使用注解@ExceptionHandler实现异常处理;
3 实战
一:使用Spring MVC提供的简单异常处理器SimpleMappingExceptionResolver
源码介绍:
1.lib包(jar包)和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>
2.index.jsp(测试页面入口)和 error.jsp(有错误则会跳到此页面)和 hello.jsp(没错误则会跳到此页面)
<%@ 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>异常处理器测试</title> </head> <body> <form action="frist.do" method="post"> <input type="submit" value="测试" /> </form> </body> </html>
<%@ 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>这是错误页面</title> </head> <body> 这是错误页面 ${ex.message } </body> </html>
<%@ 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>成功欢迎页面</title> </head> <body> 你竟然没报错<br/> </body> </html>
3.MyController,java(定义自己的处理器)
package cn.zhang.controller; //定义自己的处理器 import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; @Controller public class MyController{ @RequestMapping(value="/frist.do",produces="text/html;charset=utf-8",method=RequestMethod.POST) public String frist(){ //制造一个异常 int i=5/0; System.out.println(i); return "forward:/hello.jsp"; } }
4.applicationContext.xml(Spring的配置文件)
<?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: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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <!-- 使用注解方式完成映射 --> <context:component-scan base-package="cn.zhang.controller"></context:component-scan> <!-- mvc的注解驱动 --> <mvc:annotation-driven /> <!-- 注册系统异常处理器 --> <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"> <property name="defaultErrorView" value="error.jsp"></property> <property name="exceptionAttribute" value="ex"></property> </bean> </beans>
测试展示:
点击测试,由于我们在自己的处理器制造了一个异常,所以它会跳到错误页面
二:实现Spring的异常处理接口SimpleMappingExceptionResolver自定义自己的异常处理器
源码介绍:
1.lib包和web.xml一样(不做解释)
2.error包中是指定错误页面
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>年龄错误页面</title> </head> <body>年龄错误 ${ex.message } </body> </html>
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>名字错误页面</title> </head> <body> 名字错误 ${ex.message } </body> </html>
3.MyController.java
package cn.zhang.controller; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import cn.zhang.exception.AgeException; import cn.zhang.exception.NameException; import cn.zhang.exception.UserException; //定义自己的处理器 @Controller public class MyController{ @RequestMapping(value="/frist.do") public String frist(Model model,String name,int age) throws UserException{ if (name.equals("admin")) { throw new NameException("用户名错误"); } if (age>50) { throw new AgeException("年龄过大"); } return "forward:/hello.jsp"; } }
4.exception包下,指定我们的异常类
UserException.java
package cn.zhang.exception; //定义UserException继承Exception public class UserException extends Exception { private static final long serialVersionUID = 1L; public UserException() { super(); // TODO Auto-generated constructor stub } public UserException(String message) { super(message); // TODO Auto-generated constructor stub } }
AgeException.java
package cn.zhang.exception; //继承UserException父类 public class AgeException extends UserException { private static final long serialVersionUID = 1L; public AgeException() { super(); // TODO Auto-generated constructor stub } public AgeException(String message) { super(message); // TODO Auto-generated constructor stub } }
NameException.java
package cn.zhang.exception; //继承UserException父类 public class NameException extends UserException { private static final long serialVersionUID = 1L; public NameException() { super(); // TODO Auto-generated constructor stub } public NameException(String message) { super(message); // TODO Auto-generated constructor stub } }
5.applicationContext.xml(Spring的配置文件)
<?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: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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <!-- 使用注解方式完成映射 --> <context:component-scan base-package="cn.zhang.controller"></context:component-scan> <!-- mvc的注解驱动 --> <mvc:annotation-driven /> <!-- 实现Spring的异常处理接口HandlerExceptionResolver 自定义自己的异常处理器 --> <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"> <property name="defaultErrorView" value="error.jsp"></property> <property name="exceptionAttribute" value="ex"></property> <!-- 指定错误到指定页面 --> <property name="exceptionMappings"> <props> <prop key="cn.zhang.exception.AgeException">error/ageerrors.jsp</prop> <prop key="cn.zhang.exception.NameException">error/nameerrors.jsp</prop> </props> </property> </bean> </beans>
结果展示:
三:实现HandlerExceptionResolver 接口自定义异常处理器
要修改的代码:
1.MyHandlerExceptionResolver.java--定义自己的异常处理器(实现HandlerExceptionResolver接口)
package cn.zhang.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.zhang.exception.AgeException; import cn.zhang.exception.NameException; /** * 定义自己的异常处理器(实现HandlerExceptionResolver接口) * @author zhangzong * */ 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"); if(ex instanceof NameException){ mv.setViewName("/error/nameerrors.jsp"); } if(ex instanceof AgeException){ mv.setViewName("/error/ageerrors.jsp"); } return mv; } }
2.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: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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <!-- 使用注解方式完成映射 --> <context:component-scan base-package="cn.zhang.controller"></context:component-scan> <!-- mvc的注解驱动 --> <mvc:annotation-driven /> <!-- 注册自定义异常处理器 --> <bean class="cn.zhang.resolvers.MyHandlerExceptionResolver"/> </beans>
其他的相同,不作解释
四:使用注解@ExceptionHandler实现异常处理
源码介绍:
1.其他配置相同(不做解释)
2.MyController.java--继承我们自己定义的注解异常处理器MyHandlerExceptionResolver
package cn.zhang.controller; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import cn.zhang.exception.AgeException; import cn.zhang.exception.NameException; import cn.zhang.exception.UserException; import cn.zhang.resolvers.MyHandlerExceptionResolver; //定义自己的处理器 //继承我们自己定义的注解异常处理器MyHandlerExceptionResolver @Controller public class MyController extends MyHandlerExceptionResolver{ @RequestMapping(value="/frist.do") public String frist(Model model,String name,int age) throws UserException{ if (name.equals("admin")) { throw new NameException("用户名错误"); } if (age>50) { throw new AgeException("年龄过大"); } return "forward:/hello.jsp"; } }
3.MyHandlerExceptionResolver.java--定义自己的异常处理器(使用注解)
package cn.zhang.resolvers; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.servlet.ModelAndView; import cn.zhang.exception.AgeException; import cn.zhang.exception.NameException; /** * 定义自己的异常处理器(使用注解) * @author zhangzong * */ @Controller public class MyHandlerExceptionResolver{ @ExceptionHandler public ModelAndView resolveException(Exception ex) { ModelAndView mv=new ModelAndView(); mv.addObject("ex",ex); mv.setViewName("/errors.jsp"); if(ex instanceof NameException){ mv.setViewName("/error/nameerrors.jsp"); } if(ex instanceof AgeException){ mv.setViewName("/error/ageerrors.jsp"); } return mv; } }
4.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: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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <!-- 使用注解方式完成映射 --> <context:component-scan base-package="cn.zhang.controller"></context:component-scan> <!-- mvc的注解驱动 --> <mvc:annotation-driven /> <!-- 注册自定义异常处理器 --> <bean class="cn.zhang.resolvers.MyHandlerExceptionResolver"/> </beans>
效果和上相同,这里不做展示
标签:encoding eth att nat gets display init 目的 pack
原文地址:http://www.cnblogs.com/zhangzongle/p/6087500.html