今天復(fù)習(xí)了JSP腳本元素和注釋部分，案例寫(xiě)出來(lái)，大家自己調(diào)試下，整體總結(jié)如下，
1、JSP申明語(yǔ)句：
<%！申明語(yǔ)句 %>
使用申明語(yǔ)句的變量為全局變量，多個(gè)用戶執(zhí)行此JSP頁(yè)面，將共享該變量。
如：

復(fù)制代碼代碼如下:

 
<html> 
<head> 
<title>JSP Demo</title> 
</head> 
<body> 
<%! int a = 1 ;%> 
<% 
out.println("a="+a); 
a++; 
%> 
</body> 
</html> 

結(jié)果如下：

再次刷新，會(huì)發(fā)現(xiàn)如下a的值加一了，因?yàn)樽兞縜是全局變量，a++運(yùn)算多次累計(jì)，多用客服端共享：

2、JSP Scriptlets：
<% Java代碼%>
在JSP Scriptlets中可包含多個(gè)語(yǔ)句，如：方法，變量，表達(dá)式等；
如：

復(fù)制代碼代碼如下:

 
<html> 
<head> 
<title>test demo</title> 
</head> 
<body> 
<% 
String str = "Hello,xiaomo!"; 
out.println(str); 
%> 
</body> 
</html> 

結(jié)果如下：

3、JSP表達(dá)式：
<%= Java代碼 %>
一種簡(jiǎn)單的輸出形式，必須有一個(gè)可以輸出的值，表達(dá)式中的代碼會(huì)首先執(zhí)行，然后轉(zhuǎn)換成字符串顯示到頁(yè)面。
如：

復(fù)制代碼代碼如下:

 
<html> 
<head> 
<title>test demo</title> 
</head> 
<body> 
<% String str = "Hello,xiaomo!"; %> 
<%= str %> 
</body> 
</html> 

結(jié)果如下：

4、JSP注釋：
 HTML注釋，會(huì)顯示于客戶端；
<%-- --%>JSP注釋，不會(huì)顯示于客戶端；
如：

復(fù)制代碼代碼如下:

 
<html> 
<head> 
<title>test demo</title> 
</head> 
<body> 
<!-- 這是一個(gè)網(wǎng)頁(yè)注釋 --> 
<%-- 這是一個(gè)JSP注釋 --%> 
</body> 
</html> 

結(jié)果如下：

大家發(fā)現(xiàn)都沒(méi)有什么顯示，點(diǎn)擊瀏覽器右鍵查看源碼可以看到網(wǎng)頁(yè)注釋是在的，JSP注釋沒(méi)有，這個(gè)只有在JSP源碼才能看到：

復(fù)制代碼代碼如下:

 
<html> 
<head> 
<title>test demo</title> 
</head> 
<body> 
<!-- 這是一個(gè)網(wǎng)頁(yè)注釋 --> 
</body> 
</html> 

應(yīng)該很多人都知道，JSP頁(yè)面是轉(zhuǎn)譯成Servlet后在通過(guò)服務(wù)器轉(zhuǎn)換成html代碼發(fā)送到客戶端顯示的，下面給大家看下本案例的JSP頁(yè)面轉(zhuǎn)換成Servlet后的源碼（其中紅色標(biāo)注為轉(zhuǎn)換成前臺(tái)的html代碼）：

復(fù)制代碼代碼如下:

 
/* 
* Generated by the Jasper component of Apache Tomcat 
* Version: Apache Tomcat/7.0.34 
* Generated at: 2013-07-03 01:27:37 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 HelloXiaoMo_jsp extends org.apache.jasper.runtime.HttpJspBase 
implements org.apache.jasper.runtime.JspSourceDependent { 
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=utf-8"); 
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("\t<head>\r\n"); 
out.write("\t\t<title>test demo</title>\r\n"); 
out.write("\t</head>\r\n"); 
out.write("\t<body>\r\n"); 
out.write("\t\t<!-- 這是一個(gè)網(wǎng)頁(yè)注釋 -->\r\n"); 
out.write("\t\t"); 
out.write("\r\n"); 
out.write("\t</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); 
} 
} 
} 