Web 项目中异常处理
jsp中错误处理页面
举例说明：mustBeError.jsp
<%@ page contentType= "text/html; charset=gb2312"
language= "java" import= "java.sql.*,javax.servlet.*,javax.servlet.http.*" errorPage= "error.jsp" %>
<%
//这个页面一定会出错。
int i=0;
int j=1;
out.println(j/i);
%>
在此中通过errorPage= "error.jsp" 来指定出错时错误处理页面
<--------------------------->
error.jsp
<%@ page contentType= "text/html; charset=gb2312" language= "java" isErrorPage= "true" import= "java.io.*" %>
<html>
<head>
<title>出错了！</title>
<meta http-equiv= "Content-Type" content= "text/html; charset=gb2312" >
</head>
<body>
出错了！<br>
发生了以下的错误：
<br><hr><font color=red><hr>
getMessage():<br>
<%=exception.getMessage()%><br><hr>
getLocalizedMessage():<br>
<%=exception.getLocalizedMessage()%><br><hr>
PrintStatckTrace():<br>
<%
StringWriter sw=new StringWriter();
PrintWriter pw=new PrintWriter(sw);
exception.printStackTrace(pw);
out.println(sw);
%><br>
</font></body>
</html>
在error.jsp中，page指令中指定:isErrorPage= "true"
<---------------------->
在web.xml中声明异常和错误页面
例如：
<?xml version= "1.0" encoding= "ISO-8859-1" ?>
<web-app xmlns= "http://java.sun.com/xml/ns/j2ee"
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation= "http://java.sun.com/xml/ns/j2ee web-app_2_4.xsd"
version= "2.4" >
<error-page>
<error-code>404</error-code>
<location>/pageNotFound.html</location>
</error-page>
<error-page>
<exception-type>java.lang.NumberFormatException</exception-type>
<location>/NumberFormatException.html</location>
</error-page>
</web-app>
说明：指定错误代码为404是，调用/pageNotFound.html
也可以指定错误类型如：java.lang.NumberFormatException，出现此错误类型是调用/NumberFormatException.html