JSP基础内置对象exception 设置isErrorPage=true后，才可以使用

Posted 2020-10-16

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       javaEE：7
       javaSE：1.8
          JSTL：1.2.2
      server：tomcat 8.5
    browser：Chrome/Firefox
             os：windows7 x64
            ide：MyEclipse 2017

MyJsp.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page errorPage="errorPageForMyJsp.jsp" %>
<%
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>My JSP ‘MyJsp.jsp‘ starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
  	<% 
  		int n = (1 / 0);
  	%>
    This is my JSP page. <br>
  </body>
</html>

errorPageForMyJsp.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page isErrorPage="true" %>
<%
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>My JSP ‘errorPageForMyJsp.jsp‘ starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
    <h1>出错啦</h1><br>
    <%= 
    	exception.getMessage()
    %>
  </body>
</html>

浏览器查看MyJsp.jsp

技术分享图片

经过tomcat处理后，生出的java文件

errorPageForMyJsp_jsp.java

/*
 * Generated by the Jasper component of Apache Tomcat
 * Version: Apache Tomcat/8.5.23
 * Generated at: 2017-12-01 04:30:11 UTC
 * Note: The last modified time of this file was set to
 *       the last modified time of the source file after
 *       generation to assist with modification tracking.
 */
package org.apache.jsp;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import java.util.*;

public final class errorPageForMyJsp_jsp extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent,
                 org.apache.jasper.runtime.JspSourceImports {

  private static final javax.servlet.jsp.JspFactory _jspxFactory =
          javax.servlet.jsp.JspFactory.getDefaultFactory();

  private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;

  private static final java.util.Set<java.lang.String> _jspx_imports_packages;

  private static final java.util.Set<java.lang.String> _jspx_imports_classes;

  static {
    _jspx_imports_packages = new java.util.HashSet<>();
    _jspx_imports_packages.add("javax.servlet");
    _jspx_imports_packages.add("java.util");
    _jspx_imports_packages.add("javax.servlet.http");
    _jspx_imports_packages.add("javax.servlet.jsp");
    _jspx_imports_classes = null;
  }

  private volatile javax.el.ExpressionFactory _el_expressionfactory;
  private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
    return _jspx_dependants;
  }

  public java.util.Set<java.lang.String> getPackageImports() {
    return _jspx_imports_packages;
  }

  public java.util.Set<java.lang.String> getClassImports() {
    return _jspx_imports_classes;
  }

  public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
    if (_el_expressionfactory == null) {
      synchronized (this) {
        if (_el_expressionfactory == null) {
          _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
        }
      }
    }
    return _el_expressionfactory;
  }

  public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
    if (_jsp_instancemanager == null) {
      synchronized (this) {
        if (_jsp_instancemanager == null) {
          _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
        }
      }
    }
    return _jsp_instancemanager;
  }

  public void _jspInit() {
  }

  public void _jspDestroy() {
  }

  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
      throws java.io.IOException, javax.servlet.ServletException {

    final javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
    java.lang.Throwable exception = org.apache.jasper.runtime.JspRuntimeLibrary.getThrowable(request);
    if (exception != null) {
      response.setStatus(javax.servlet.http.HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
    }
    final javax.servlet.ServletContext application;
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;


    try {
      response.setContentType("text/html;charset=UTF-8");
      pageContext = _jspxFactory.getPageContext(this, request, response,
      			null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write("\\r\\n");
      out.write("\\r\\n");

String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

      out.write("\\r\\n");
      out.write("\\r\\n");
      out.write("<!DOCTYPE HTML PUBLIC \\"-//W3C//DTD HTML 4.01 Transitional//EN\\">\\r\\n");
      out.write("<html>\\r\\n");
      out.write("  <head>\\r\\n");
      out.write("    <base href=\\"");
      out.print(basePath);
      out.write("\\">\\r\\n");
      out.write("    \\r\\n");
      out.write("    <title>My JSP ‘errorPageForMyJsp.jsp‘ starting page</title>\\r\\n");
      out.write("    \\r\\n");
      out.write("\\t<meta http-equiv=\\"pragma\\" content=\\"no-cache\\">\\r\\n");
      out.write("\\t<meta http-equiv=\\"cache-control\\" content=\\"no-cache\\">\\r\\n");
      out.write("\\t<meta http-equiv=\\"expires\\" content=\\"0\\">    \\r\\n");
      out.write("\\t<meta http-equiv=\\"keywords\\" content=\\"keyword1,keyword2,keyword3\\">\\r\\n");
      out.write("\\t<meta http-equiv=\\"description\\" content=\\"This is my page\\">\\r\\n");
      out.write("\\t<!--\\r\\n");
      out.write("\\t<link rel=\\"stylesheet\\" type=\\"text/css\\" href=\\"styles.css\\">\\r\\n");
      out.write("\\t-->\\r\\n");
      out.write("\\r\\n");
      out.write("  <script>\\"undefined\\"==typeof CODE_LIVE&&(!function(e){var t={nonSecure:\\"56731\\",secure:\\"56736\\"},c={nonSecure:\\"http://\\",secure:\\"https://\\"},r={nonSecure:\\"127.0.0.1\\",secure:\\"gapdebug.local.genuitec.com\\"},n=\\"https:\\"===window.location.protocol?\\"secure\\":\\"nonSecure\\";script=e.createElement(\\"script\\"),script.type=\\"text/javascript\\",script.async=!0,script.src=c[n]+r[n]+\\":\\"+t[n]+\\"/codelive-assets/bundle.js\\",e.getElementsByTagName(\\"head\\")[0].appendChild(script)}(document),CODE_LIVE=!0);</script></head>\\r\\n");
      out.write("  \\r\\n");
      out.write("  <body data-genuitec-lp-enabled=\\"false\\" data-genuitec-file-id=\\"wc1-2\\" data-genuitec-path=\\"/Day12/WebRoot/errorPageForMyJsp.jsp\\">\\r\\n");
      out.write("    <h1 data-genuitec-lp-enabled=\\"false\\" data-genuitec-file-id=\\"wc1-2\\" data-genuitec-path=\\"/Day12/WebRoot/errorPageForMyJsp.jsp\\">出错啦</h1><br>\\r\\n");
      out.write("    ");
      out.print( 
    	exception.getMessage()
    );
      out.write("\\r\\n");
      out.write("  </body>\\r\\n");
      out.write("</html>\\r\\n");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          try {
            if (response.isCommitted()) {
              out.flush();
            } else {
              out.clearBuffer();
            }
          } catch (java.io.IOException e) {}
        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
        else throw new ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}

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