一、概述

在项目中总会出现各种异常、bug，为了使得用户体验更好，当系统出现异常的时候，我们需要有我们的处理方式，使得用户能够理解系统出现了什么问题。

二、异常类

首先我们需要编写一个异常类

package org.sihai.qualitycontrol.utils.exception;

public class AppException extends RuntimeException{

    public AppException() {
        super();
    }

    public AppException(String message, Throwable cause) {
        super(message, cause);
    }

    public AppException(String message) {
        super(message);
    }

    public AppException(Throwable cause) {
        super(cause);
    }
    
}

三、异常处理拦截器

在有了异常类之后，当出现异常的时候，我们需要有拦截器来拦截，然后转发到异常页面。

package org.sihai.qualitycontrol.utils.interceptor;

import org.apache.struts2.ServletActionContext;
import org.sihai.qualitycontrol.utils.exception.AppException;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

public class ExceptionInterceptor extends AbstractInterceptor{

    public String intercept(ActionInvocation invocation) throws Exception {
        try {
            return invocation.invoke();
        } catch (AppException e) {
            //记录日志
            //发送日志到程序员邮箱
            //报警
            ActionSupport as = (ActionSupport) invocation.getAction();
            as.addActionError(as.getText(e.getMessage()));
            ServletActionContext.getContext().getSession().put("flag", "yes");
            return "systemerror";
        } catch (Exception e) {
            ActionSupport as = (ActionSupport) invocation.getAction();
            as.addActionError("对不起，服务器有点累了，请联系管理员！");
            ServletActionContext.getContext().getSession().put("flag", "yes");
            System.out.println(e.getStackTrace());
            return "systemerror";
        }
    }
    
}

关于拦截器的配置请查看：ssh项目实战----用户登录校验（struts拦截器）

四、异常处理页面

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<%@taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="">
<meta name="author" content="">
<title>系统繁忙</title>
<style>
body,html {  
margin: 0;  
padding: 0;  
height:100%;  
}  
#content {  
min-height:100%;  
position: relative;  
}  
#footer {  
position: absolute;  
bottom: 0;  
padding: 10px 0;  
width: 100%;  
}  
</style>
<!-- Bootstrap core CSS -->
<link href="css/bootstrap.min.css" rel="stylesheet">
<!-- FONT AWESOME CSS -->
<link href="font-awesome/css/font-awesome.min.css" rel="stylesheet" />
<!--GOOGLE FONT -->
<link href='http://fonts.googleapis.com/css?family=Nova+Flat'
    rel='stylesheet' type='text/css'>
<!-- custom CSS here -->
<link href="css/404.css" rel="stylesheet" />
</head>
<body>

    <div class="container" id="content">

        <div class="row pad-top text-center">
            <s:if test="#session.flag != 'yes'">
                <div class="col-md-6 col-md-offset-3 text-center">
                    <h1>hi，不好意思</h1>
                    <h5>系统有点累了</h5>
                    <span id="error-link"></span>
                    <h2>请检查网络，返回主页，稍后再试！</h2>
                </div>
            </s:if>
            <s:else>
                <div class="col-md-6 col-md-offset-3 text-center">
                    <h2><s:actionerror /></h2>
                </div>
            </s:else>
        </div>

        <div class="row text-center" id="footer">
            <div class="col-md-8 col-md-offset-2">

                <h3>
                    <i class="fa fa-lightbulb-o fa-5x"></i>
                </h3>
                <a href="page_toIndex" class="btn btn-primary">主页</a> <br />
                <br />Copyright &copy; 2017 赣南师范大学 <a href="page_toIndex"
                    title="国家脐橙工程技术研究中心" target="_blank">国家脐橙工程技术研究中心</a>
            </div>
        </div>

    </div>

    <!--Core JavaScript file  -->
    <script src="js/jquery.js"></script>
    <!--bootstrap JavaScript file  -->
    <script src="js/bootstrap.min.js"></script>
    <!--Count Number JavaScript file  -->
    <script src="js/countUp.js"></script>
    <!--Custom JavaScript file  -->
    <script src="js/custom.js"></script>
</body>
</html>