JSP 之靜態包含

最後更新：2018-12-03 來源：互聯網

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JSP 之靜態包含 <%@ include %>

現在我們來看看JSP 的靜態包含指令: <%@ include %>

我們建立一個工程TestInclude

然後加入檔案:

Index.jsp:

<%@ page language="java"import="java.util.*" pageEncoding="ISO-8859-1"%><html>  <body>    <%@ includefile="curDate" %>    <%@ includefile="curDate.jsp" %>    <%@ includefile="curDate.html" %>    <p>this is user's area</p>  </body></html>

curDate: (不帶尾碼)

  <p>curDate: <%=new Date()%></p> <!-- curDate -->

curDate.jsp:

  <p>curDate.jsp: <%=new Date()%></p> <!—curDate.jsp-->

curDate.html:

  <p>curDate.html: <%=newDate()%></p> <!—curDate.html -->

查看結果: http://localhost:8080/TestInclude/index.jsp

查看其原始碼:

查看Tomcat 工作目錄:

查看index_jsp.java檔案:

/* * Generated by the Jasper component of Apache Tomcat * Version: Apache Tomcat/7.0.22 * Generated at: 2011-11-04 11:17:58 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. */…………這裡省略…..    try {      response.setContentType("text/html;charset=ISO-8859-1");      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("<html>\r\n");      out.write("  <body>\r\n");      out.write("  \t");      out.write("<p>curDate: ");      out.print(new Date());      out.write("</p> <!-- curDate -->");      out.write("\r\n");      out.write("  \t");      out.write("<p>curDate.jsp: ");      out.print(new Date());      out.write("</p> <!-- curDate -->");      out.write("\r\n");      out.write("  \t");      out.write("<p>curDate.html: ");      out.print(new Date());      out.write("</p> <!-- curDate.html -->");      out.write("\r\n");      out.write("  \t<p>this is user's area</p>\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 { out.clearBuffer(); } catch (java.io.IOException e) {}        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);      }    } finally {      _jspxFactory.releasePageContext(_jspx_page_context);    }  }}

分析總結:

Tomcat工作目錄下只編譯了index.jsp檔案, curDate.jsp沒有被產生.java檔案,再對比了.html和無尾碼的檔案,其內容是相似的,所以這個靜態包含指令,其實和被包含的檔案的格式無關,只有是本文即可,所以可推測到其”包含”這個動作,就是要index.jsp被轉成.java(Servlet)前,要做的工作僅僅是把目標檔案包含進去index.jsp中,簡單替換了原有的指令而已…

so 靜態包含 <%@ include %> == 文本替換

PS:

Directive(編譯指令)相當於在編譯期間的命令格式：<%@Directive 屬性=“屬性值”%>這種格式的指令都是編譯期進行的,而不是在運行時(Runtime)進行的

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