和的区别

前天上了jsp的课，老师讲了一下<%@include%>和的区别，由于演示的太快，我没有看太清，所以回来之后，自己又写了个例子，好好看看，还是发现了一些东西的。

：动态包含

第一种情况（包含的是html文件）：

DynamicInclude.jsp:

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

         
                   
         
         
 
                   
 
                   
                            
                                     姓名性别年龄爱好
                            
                            
                                     abcd
                            
                   
         

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\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\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
a
b
c
d
\r\n");
     out.write("\t\r\n");
     out.write("");

第二种情况（包含的是jsp文件）：

DynamicInclude.jsp:

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

         
                   
         
         
 
                   
 
                   
                            
                                     姓名性别年龄爱好
                            
                            
                                     abcd
                            
                   
         

Header.jsp ：

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

         
                   
                            动态包含的标题(JSP)
                   
         

运行之后，生成了两个servlet：DynamicInclude_jsp.java和header_jsp.java，这也是为什么 Header.jsp中要写上<%@page contentType="text/html;charset=gb2312"%>和完整的和，而Header.html不用写的原因。因为前者两个.jsp文件是两个相互独立的整体，它们之间的关系是通过request和reponse来发生的，而后者只是简单的嵌套。两个servlet对应的代码如下：

DynamicInclude_jsp.java：

     out.write("\r\n");
     out.write("\r\n");
     out.write("\t\r\n");
     out.write("\t\t\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
a
b
c
d
\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"%>

         
                   
         
         
 
                   <%@include file="header.jsp"%>
                   
                            
                                     姓名性别年龄爱好
                            
                            
                                     abcd
                            
                   
         

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\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\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
a
b
c
d
\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"%>

         
                   
         
         
 
                   <%@include file="header.html"%>
                   
                            
                                     姓名性别年龄爱好
                            
                            
                                     abcd
                            
                   
         

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\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\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
a
b
c
d
\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，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。