<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!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>Insert title here</title> </head> <body> <% //out.write(session.toString()+" "+session.isNew()); if(session==null){ out.write("session not creat"); } else if(session.getAttribute("name")==null||session.getAttribute("name").equals("")){ out.write("<a href='login.jsp'>登录</a>"); } else{ out.write(session.getAttribute("name")+"你好"); } %> / <a href="index.jsp" onclick="logout()">注销</a> <script type="text/javascript"> function logout(){ <% session.invalidate(); %> } </script> </body> </html>
index.jsp编译后文件为
/* * Generated by the Jasper component of Apache Tomcat * Version: Apache Tomcat/7.0.63 * Generated at: 2016-10-13 10:50:27 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.*; public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase implements org.apache.jasper.runtime.JspSourceDependent { 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 javax.el.ExpressionFactory _el_expressionfactory; private org.apache.tomcat.InstanceManager _jsp_instancemanager; public java.util.Map<java.lang.String,java.lang.Long> getDependants() { return _jspx_dependants; } public void _jspInit() { _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory(); _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig()); } 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; 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(" "); out.write("<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> "); out.write("<html> "); out.write("<head> "); out.write("<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> "); out.write("<title>Insert title here</title> "); out.write(" "); out.write("</head> "); out.write("<body> "); out.write(" "); //out.write(session.toString()+" "+session.isNew()); if(session==null){ out.write("session not creat"); } else if(session.getAttribute("name")==null||session.getAttribute("name").equals("")){ out.write("<a href='login.jsp'>登录</a>"); } else{ out.write(session.getAttribute("name")+"你好"); } out.write(" "); out.write(" / "); out.write(" <a href="index.jsp" onclick="logout()">注销</a> "); out.write(" <script type="text/javascript"> "); out.write(" function logout(){ "); out.write(" "); session.invalidate(); out.write(" "); out.write(" } "); out.write(" </script> "); out.write("</body> "); out.write("</html>"); } 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); } } }
关于里面的javascript语言，如果写在<head>标签中的话在生成java代码时，session元素会先调用invalidate()方法，然后就无session对象了，导致后面的session对象不存在产生java.lang.IllegalStateException异常。所以在JavaScript中嵌套java语言时，要满足java编译的需求。