JSP的异常处理
方法1：使用Exception对象
exception对象是Throwable子类的一个实例，只在错误页面中可用。
看一个例子：
<%@ page errorPage="ShowError.jsp" %>
<html>
<head>
<title>Error Handling Example</title>
</head>
<body>
<% // Throw an exception to invoke the error page
int x = 1; if (x == 1) {
throw new RuntimeException("Error condition!!!");
} %>
</body>
</html>使用<%@page errorPage=“XXXXX”%>指令指定一个错误页面ShowError.jsp.
ShowError.jsp的源代码：
<%@ page isErrorPage="true" %>
<html>
<head>
<title>Show Error Page</title>
</head>
<body>
<h1>Opps...</h1>
<p>Sorry, an error occurred.</p>
<p>Here is the exception stack trace: </p>
<pre>
<% exception.printStackTrace(response.getWriter()); %>注意，在浏览器里，虽然访问的是main.jsp, 但实际上显示的内容已经是ShowError.jsp的实现了：
打印出的错误堆栈信息：
java.lang.RuntimeException: Error condition!!! at org.apache.jsp.main_jsp._jspService(main_jsp.java:125) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329) at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)
Opps...方法2：在错误页面中使用JSTL标签
将ShowError.jsp的内容替换成如下：
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@page isErrorPage="true" %>
<html>
<head>
<title>Show Error Page</title>
</head>
<body>
<h1>Opps...</h1>
<table width="100%" border="1">
<tr valign="top">
<td width="40%"><b>Error:</b></td>
<td>${pageContext.exception}</td>
</tr>
<tr valign="top">
<td><b>URI:</b></td>
<td>${pageContext.errorData.requestURI}</td>
</tr>
<tr valign="top">
<td><b>Status code:</b></td>
<td>${pageContext.errorData.statusCode}</td>
</tr>
<tr valign="top">
<td><b>Stack trace:</b></td>
<td>
<c:forEach var="trace" items="${pageContext.exception.stackTrace}">
<p>${trace}</p>
</c:forEach>
</td>
</tr>
</table>
</body>
</html>测试结果：
方法3：使用 try…catch块
如果想要将异常处理放在一个页面中，并且对不同的异常进行不同的处理，那么就需要使用try…catch块了。
main.jsp的源代码：
<html>
<head>
<title>Try...Catch Example</title>
</head>
<body>
<% try{ int i = 1; i = i / 0; out.println("The answer is " + i); } catch (Exception e){ out.println("An exception occurred: " + e.getMessage()); } %>
</body>
</html>本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2020-07-18 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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