两种include的区别

<%@include%>和jsp:include的区别,发现了一些东西的。

<%@include%>:页面请求之前预编译,所有代码包含进来之后,一起进行处理,把所有代码合在一起,编译成一个servlet

jsp:include:所有代码分别处理,在页面被请求的时候才编译,被编译成多个servlet,页面语法相对独立,处理完成之后再将代码的显示结果(处理结果)组合进来。

JSP中的两种包含页面的方法
第一种:include指令:当JSP转换成Servlet时引入指定文件

<%@ pagecontentType=“text/html;charset=GB2312” language=“java"errorPage=”"%>
<%@ include file=“head.jsp”%>
<%@ include file=“body.jsp”%>
<%@ include file=“tail.jsp”%>
第二种:jsp:include动作元素:当JSP页面被请求时引入指定文件
<%@ page contentType=“text/html; charset=GB2312"language=“java” errorPage=”"%>



第二种方法可以很方便的用jsp:param来向所包含页传递参数,方法如下:
<%@ page contentType=“text/html; charset=GB2312"language=“java” errorPage=”"%>

jsp:includepage=“body.jsp”



jsp:includepage=“tail.jsp”/

jsp:include :动态包含

第一种情况(jsp:include包含的是html文件):

DynamicInclude.jsp:

<%@pagecontentType=“text/html;charset=gb2312”%>

动态包含

Header.html :


动态包含的标题(HTML)

运行之后,只生成一个servlet,和上面的代码对应如下:

out.write("\r\n");
out.write("\r\n");
out.write("\t\r\n");
out.write("\t\t动态包含\r\n");
out.write("\t\r\n");
out.write("\t\r\n");
out.write("\r\n");
out.write("\t\t");
org.apache.jasper.runtime.JspRuntimeLibrary.include(request,response, “header.html”, out, true);
out.write(" \r\n");
out.write("\r\n");
out.write("\t\t

\r\n”);
out.write("\t\t\t\r\n");
out.write("\t\t\t\t姓名性别年龄爱好\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\t\tabcd\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\r\n");
out.write("\t\r\n");
out.write("");

第二种情况(jsp:include包含的是jsp文件):

DynamicInclude.jsp:

<%@pagecontentType=“text/html;charset=gb2312”%>

动态包含 Header.jsp :

<%@pagecontentType=“text/html;charset=gb2312”%>

DynamicInclude_jsp.java:

 out.write("\r\n");
 out.write("\r\n");
 out.write("\t\r\n");
 out.write("\t\t动态包含\r\n");
 out.write("\t\r\n");
 out.write("\t\r\n");
 out.write("\r\n");
 out.write("\t\t");
 org.apache.jasper.runtime.JspRuntimeLibrary.include(request,response, "header.jsp", out, true);
 out.write("\r\n");
 out.write("\r\n");
 out.write("\t\t
\r\n"); out.write("\t\t\t\r\n"); out.write("\t\t\t\t\r\n"); out.write("\t\t\t\r\n"); out.write("\t\t\t\r\n"); out.write("\t\t\t\t\r\n"); out.write("\t\t\t\r\n"); out.write("\t\t
姓名性别年龄爱好
abcd
\r\n"); out.write("\t\r\n"); out.write("");

header_jsp.java:

 out.write("\r\n");
 out.write("\r\n");
 out.write("\t\r\n");
 out.write("\t\t

\r\n"); out.write("\t\t\t动态包含的标题(JSP)\r\n"); out.write("\t\t

\r\n"); out.write("\t\r\n"); out.write("");

<%@include%>:静态包含

第一种情况:<%@include%>包含的是jsp文件。

StaticInclude.jsp:

<%@pagecontentType=“text/html;charset=gb2312”%>

静态包含 header.jsp:

<%@pagecontentType=“text/html;charset=gb2312”%>

静态包含的标题(JSP)

运行之后,只生成一个servlet,和上面的代码对应如下:

out.write("\r\n");
out.write("\r\n");
out.write("\t\r\n");
out.write("\t\t静态包含\r\n");
out.write("\t\r\n");
out.write("\t\r\n");
out.write("\r\n");
out.write("\t\t");
out.write("\r\n");
out.write("\r\n");
out.write("\t静态包含的标题(JSP)\r\n");
out.write("");

out.write(" \r\n");
out.write("\t\t

\r\n”);
out.write("\t\t\t\r\n");
out.write("\t\t\t\t姓名性别年龄爱好\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\t\tabcd\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\r\n");
out.write("\t\r\n");
out.write("");

第二种情况:<%@include%>包含的是html文件。

StaticInclude.jsp:

<%@pagecontentType=“text/html;charset=gb2312”%>

静态包含 header.html:

<%@pagecontentType=“text/html;charset=gb2312”%>

静态包含的标题(HTML)

运行之后,也是只生成一个servlet,和上面的代码对应如下:

out.write("\r\n");
out.write("\r\n");
out.write("\t\r\n");
out.write("\t\t静态包含\r\n");
out.write("\t\r\n");
out.write("\t\r\n");
out.write("\r\n");
out.write("\t\t");
out.write("\r\n");
out.write("\r\n");
out.write("\t静态包含的标题(HTML)\r\n");
out.write("");

out.write(" \r\n");
out.write("\t\t

\r\n”);
out.write("\t\t\t\r\n");
out.write("\t\t\t\t姓名性别年龄爱好\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\t\tabcd\r\n");
out.write("\t\t\t\r\n");
out.write("\t\t\r\n");
out.write("\t\r\n");
out.write("");

由上可以总结出:

对于静态包含,<%@include%>,中包含的文件,只是简单的嵌入到主文件中,就是在jsp页面转化成Servlet时才嵌入到主文件中,因为运行的结果是只生成了一个Servlet。

而对于动态包含jsp:incude,如果被包含文件是动态的,那么就会生成两个Servlet,也就是被包含文件也要经过jsp引擎编译执行生成一个Servlet,两个Servlet通过request和reponse进行通信。如果被包含的文件是静态的,那么这种情况和%@include就很相似,只生成了一个Servlet,但是他们之间没有进行简单的嵌入,而依然是通过request和reponse进行的通信。

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