<%@ page contentType="text/html;charset=UTF-8" %> <%session.setAttribute("pageContext", "it315"); %> 輸出表達式\\${pageContext}的值：<br/> ${pageContext}

【web.xml】錯誤地在 web.xml中禁用了 jsp腳本元素

<jsp-config><jsp-property-group><url-pattern>*.jsp</url-pattern><page-encoding>UTF-8</page-encoding></jsp-property-group><!-- 忽略EL表達式 --><jsp-property-group><url-pattern>*.jsp</url-pattern><el-ignored>true</el-ignored></jsp-property-group><!-- 禁用 jsp 腳本元素 --><jsp-property-group><url-pattern>*.jsp</url-pattern><scripting-invalid>true</scripting-invalid></jsp-property-group></jsp-config>

【報錯信息如下】

【解決方法】 在web.xml中 把 禁用 jsp 腳本元素的配置信息刪除即可；

【訪問效果如下】

【web.xml 源碼】

<?xml version="1.0" encoding="ISO-8859-1"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"><servlet><servlet-name>default</servlet-name><servlet-class>org.apache.catalina.servlets.DefaultServlet</servlet-class><init-param><param-name>debug</param-name><param-value>0</param-value></init-param><init-param><param-name>listings</param-name><param-value>false</param-value></init-param><load-on-startup>1</load-on-startup></servlet><servlet-mapping><servlet-name>default</servlet-name><url-pattern>/</url-pattern></servlet-mapping><servlet><servlet-name>jsp</servlet-name><servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class><init-param><param-name>fork</param-name><param-value>false</param-value></init-param><init-param><param-name>xpoweredBy</param-name><param-value>false</param-value></init-param><load-on-startup>3</load-on-startup></servlet><servlet-mapping><servlet-name>jsp</servlet-name><url-pattern>*.jsp</url-pattern><url-pattern>*.jspx</url-pattern></servlet-mapping><mime-mapping><extension>abs</extension><mime-type>audio/x-mpeg</mime-type></mime-mapping><jsp-config><jsp-property-group><url-pattern>*.jsp</url-pattern><page-encoding>UTF-8</page-encoding></jsp-property-group><!-- 忽略EL表達式 <jsp-property-group><url-pattern>*.jsp</url-pattern><el-ignored>true</el-ignored></jsp-property-group>--><!-- 禁用 jsp 腳本元素 <jsp-property-group><url-pattern>*.jsp</url-pattern><scripting-invalid>true</scripting-invalid></jsp-property-group> --></jsp-config><!-- <filter><filter-name>FirstFilter</filter-name><filter-class>com.asite2.chapter2.ex2_3.FirstFilter</filter-class><init-param><param-name>encoding</param-name><param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>FirstFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping><filter-mapping><filter-name>FirstFilter</filter-name><servlet-name>default</servlet-name> </filter-mapping><filter-mapping><filter-name>FirstFilter</filter-name><url-pattern>/test.html</url-pattern> </filter-mapping><filter><filter-name>SecondFilter</filter-name><filter-class>com.asite2.chapter2.ex2_3.SecondFilter</filter-class><init-param><param-name>encoding</param-name><param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>SecondFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping>--><!-- <listener><listener-class>ex3_1.MyListener</listener-class></listener>--><!-- <listener><listener-class>ex3_4.CountListener</listener-class></listener><listener><listener-class>ex3_7.MyAttributeListener</listener-class></listener>--><session-config><session-timeout>1</session-timeout></session-config></web-app> 【implicitObj.jsp】 <%@ page contentType="text/html;charset=UTF-8" %> <%session.setAttribute("pageContext", "it315"); %> 輸出表達式\${pageContext}的值：<br/> ${pageContext} 【implicitObj_jsp.java】 /** Generated by the Jasper component of Apache Tomcat* Version: Apache Tomcat/7.0.35* Generated at: 2018-02-08 16:45:35 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.chapter5.ex5_005f4;import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.jsp.*;public final class implicitObj_jsp extends org.apache.jasper.runtime.HttpJspBaseimplements 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('\r');out.write('\n');session.setAttribute("pageContext", "it315");out.write("\r\n");out.write("輸出表達式${pageContext}的值：<br/>\r\n");out.write((java.lang.String) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${pageContext}", java.lang.String.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null, false));out.write(' ');} catch (java.lang.Throwable t) {if (!(t instanceof javax.servlet.jsp.SkipPageException)){out = _jspx_out;if (out != null && out.getBufferSize() != 0)try { 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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