Struts2异常处理实例
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一 介绍
java ee项目在某些情况下难免会产生一些异常，如果某些异常我们没有进行处理，那么将会抛给服务器，最后服务器会将异常信息直接在前台页面打印出来，比如说这样：
像这种直接将异常打印出来是非常不好的，不仅因为普通用户看不懂，而且还会将服务器的一些内部信息暴露出来，比如说：绝对路径，这样可能将会“方便”某些黑客进行非法入侵。因此我们需要对这些异常进行处理，给用户显示一个比较友好的界面。
二 简单处理
我们可以通过struts2的全局异常处理机制来处理，这种比较简单，配置struts.xml文件，然后添加异常页面即可。
（1）配置struts.xml ：
在package里添加：
<global-results> <result name="error">/error.html</result> </global-results> <global-exception-mappings> <exception-mapping result="error" exception="java.lang.Exception"></exception-mapping> </global-exception-mappings>
比如说我的是这样的：
<package name="bid" namespace="/bid" extends="struts-default"> <global-results> <result name="error">/error.html</result> </global-results> <global-exception-mappings> <exception-mapping result="error" exception="java.lang.Exception"></exception-mapping> </global-exception-mappings> <action name="doSubmitBid" class="bid" method="doSubmitBid"> <result name="index" type="redirect">/index.jsp</result> </action> <action name="doDeal" class="bid" method="doDeal"> <result name="index" type="redirect">/index.jsp</result> </action> </package>
（2）准备一个error页面——error.html：
这个就随便了，比如说我的是这样的：
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>出现异常啦</title>
<style type="text/css">
body {
background-image:url(‘/OnlineAuction/images/404.jpg‘);
background-repeat:no-repeat;
background-position:50% 55px;
background-attachment:fixed;
}
</style>
</head>
<body>
<div align="center" style="color:red;font-size:24px;font-weight:bold;position: relative;top:10px;">出现异常啦，请联系管理员或稍后再试！</div>
</body>
</html>（3）效果：
以上配置好以后，再次出现异常时就会这样显示了：
可以看出，现在的异常页面就比刚才友好多了
三 使用拦截器处理异常
使用这种方式就比上面的稍微多了一点步骤，不过提示的信息也要具体些，具体的步骤如下：
（1）在struts.xml文件里的package里定义拦截器：
<interceptors> <!-- 声明拦截器 --> <interceptor name="errorInterceptor" class="com.zxpm.interceptor.ErrorInterceptor" /> <!-- 配置拦截器栈 --> <interceptor-stack name="myErrorInterceptor"> <interceptor-ref name="defaultStack" /> <interceptor-ref name="errorInterceptor" /> </interceptor-stack> </interceptors> <!-- 覆盖底层的拦截器栈 对包中的所有action都有效 --> <default-interceptor-ref name="myErrorInterceptor" /> <global-results> <result name="errorMsg">/error.jsp</result> </global-results> <global-exception-mappings> <exception-mapping result="errorMsg" exception="java.lang.Exception"></exception-mapping> </global-exception-mappings>
（2）com.zxpm.interceptor.ErrorInterceptor.java对异常进行处理：
package com.zxpm.interceptor;
import java.io.IOException;
import java.sql.SQLException;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.StrutsStatics;
import org.springframework.dao.DataAccessException;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class ErrorInterceptor implements Interceptor {
public String intercept(ActionInvocation arg0) throws Exception {
try {
String result = arg0.invoke(); // Action的返回值
return result;
} catch (DataAccessException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "数据库操作失败！");
return "errorMsg";
} catch (NullPointerException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "空指针异常！");
return "errorMsg";
} catch (IOException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "IO读写异常！");
return "errorMsg";
} catch (ClassNotFoundException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "指定的类不存在！");
return "errorMsg";
} catch (ArithmeticException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "数学运算异常！");
return "errorMsg";
} catch (ArrayIndexOutOfBoundsException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "数组下标越界！");
return "errorMsg";
} catch (IllegalArgumentException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "调用方法的参数错误！");
return "errorMsg";
} catch (ClassCastException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "类型强制转换错误！");
return "errorMsg";
} catch (SecurityException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "违背安全原则异常！");
return "errorMsg";
} catch (SQLException ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "数据库操作异常！");
return "errorMsg";
} catch (NoSuchMethodError ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "调用了未定义的方法！");
return "errorMsg";
} catch (InternalError ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "Java虚拟机发生了内部错误！");
return "errorMsg";
} catch (Exception ex) {
HttpServletRequest request = (HttpServletRequest) arg0.getInvocationContext()
.get(StrutsStatics.HTTP_REQUEST);
request.setAttribute("errorMsg", "Sorry，系统发生了未知的错误，请联系管理员或稍后再试！");
return "errorMsg";
}
}
public void destroy() {
}
public void init() {
}
}（3）前台友好提示页面：
这里跟前面的差不多，多了一点对定义好的常见异常的提示，代码如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE >
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>出现异常啦</title>
<style type="text/css">
body {
background-image: url(‘/OnlineAuction/images/404.jpg‘);
background-repeat: no-repeat;
background-position: 50% 55px;
background-attachment: fixed;
}
</style>
</head>
<body>
<div align="center"
style="color: red; font-size: 24px; font-weight: bold; position: relative; top: 10px;">
<s:if test="#request.errorMsg !=null">
${requestScope.errorMsg}
</s:if>
<s:else>
系统发生未知异常，请联系管理员或稍后再试！
</s:else>
</div>
</body>
</html>（4）测试：
为了测试效果，我手动抛出了一个空指针异常：
然后进行测试，显示效果如下：
对于未定义的异常，显示的效果是这样的：
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