JSP 之 静态包含

 JSP 之 静态包含 <%@ include %>

现在我们来看看JSP 的静态包含指令: <%@ include %>

 

我们新建一个工程TestInclude

然后加入文件:

Index.jsp:

 

<%@ page language="java"import="java.util.*" pageEncoding="ISO-8859-1"%>

  
    <%@ includefile="curDate" %>
    <%@ includefile="curDate.jsp" %>
    <%@ includefile="curDate.html" %>
    
this is user's area
  

 

curDate: (不带后缀)

  
curDate: <%=new Date()%>
 

curDate.jsp:

  
curDate.jsp: <%=new Date()%>
 

curDate.html:

       

  
curDate.html: <%=newDate()%>
 

 

查看结果: http://localhost:8080/TestInclude/index.jsp

 

查看其源代码:

 

查看Tomcat 工作目录:

 

 

 

查看index_jsp.java文件:

/*
 * 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.
 */
…………这里省略…..

    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("\r\n");
      out.write("  \r\n");
      out.write("  \t");
      out.write("
curDate: ");
      out.print(new Date());
      out.write("
 ");
      out.write("\r\n");
      out.write("  \t");
      out.write("
curDate.jsp: ");
      out.print(new Date());
      out.write("
 ");
      out.write("\r\n");
      out.write("  \t");
      out.write("
curDate.html: ");
      out.print(new Date());
      out.write("
 ");
      out.write("\r\n");
      out.write("  \t
this is user's area
\r\n");
      out.write("  \r\n");
      out.write("\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);
    }
  }
}

 

分析总结:

Tomcat工作目录下只编译了index.jsp文件, curDate.jsp没有被生成.java文件,再对比了.html和无后缀的文件,其内容是相似的,所以这个静态包含指令,其实和被包含的文件的格式无关,只有是本文即可,所以可推测到其”包含”这个动作,就是要index.jsp被转成.java(Servlet)前,要做的工作仅仅是把目标文件包含进去index.jsp中,简单替换了原有的指令而已…

       so  静态包含 <%@ include %> == 文本替换

 

 

 

 PS: 

Directive(编译指令)相当于在编译期间的命令

格式：

<%@Directive 属性=“属性值”%>

这种格式的指令都是编译期进行的,而不是在运行时(Runtime)进行的