%!%和%%的区别
JSP 文件需要轉換成 Java 類。在訪問 JSP 文件的時候，并不直接執行 JSP 文件，而是執行 JSP 文件對應的 Java 類(class 文件) 的對象， 這個 Java 文件是服務器根據我們提供的 JSP 文件創建的。在 Tomcat 安裝目錄下的 work 目錄中有 JSP 文件轉換成的 Java 文件。<%!%>中定義的變量是類變量，<%%>中定義的變量是局部變量。舉例如下：
index.jsp
?
<%@ page language="java" contentType="text/html; charset=GB18030"pageEncoding="GB18030"%> <!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=GB18030"> <title>歡迎頁面</title> </head> <body> <%!int hitnumber=1; %> <%int jubu=1; %> </body> </html>?
對應的Java類：
index_jsp.java
/** Generated by the Jasper component of Apache Tomcat* Version: Apache Tomcat/8.0.3* Generated at: 2015-05-06 06:16:43 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 xixihaha_jsp extends org.apache.jasper.runtime.HttpJspBaseimplements org.apache.jasper.runtime.JspSourceDependent {int hitnumber=1; 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=GB18030");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("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n");out.write("<html>\r\n");out.write("<head>\r\n");out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=GB18030\">\r\n");out.write("<title>歡迎頁面</title>\r\n");out.write("</head>\r\n");out.write("<body>\r\n");out.write('\r');out.write('\n'); int jubu=1; out.write("\r\n");out.write("</body>\r\n");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 { 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);}} }?
轉載于:https://www.cnblogs.com/anan1688/p/4481954.html
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