–对JSP的需求 
–JSP的结构 
–JSP的好处 
–JSP实例 
?创建一个简单的JSP页面
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? JSP 
–JSP 全称Java Server Page 
?对JSP的需求 
–使用servlet可以容易地完成下述任务： 
? 读取表单数据 
? 读取HTTP请求报头 
? 设置HTTP状态代码和响应报头 
? 使用cookie以及进行会话跟踪 
?跨servlet共享数据 
? 跨请求记录数据 
? 获得有趣且报酬丰厚的工作 
? 但使用servlet也有不尽如人意的地方： 
–使用println语句生成HTML 
–维护上述的HTML
? JSP的结构 
–思想: 
?大部分的页面使用常规的HTML 
?用特殊的标签将servlet代码标记出来 
?整个JSP页面最终转换成servlet（仅执行一次），实际 
被调用的是servlet（每个请求） 
–示例
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使用Servlet输出0~9的页面
LoopServlet
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测试
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使用JSP输出0~9的页面
MyFirstJsp.jsp
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测试
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看一下JSP页面转换的Servlet文件存放在哪里哈~
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MyFirstJsp_jsp.java
package org.apache.jsp;    

import javax.servlet.*;    
import javax.servlet.http.*;    
import javax.servlet.jsp.*;    
import java.util.*;    

public  final  class MyFirstJsp_jsp  extends org.apache.jasper.runtime.HttpJspBase    
         implements org.apache.jasper.runtime.JspSourceDependent {    

     private  static  final JspFactory _jspxFactory = JspFactory.getDefaultFactory();    

     private  static java.util.List _jspx_dependants;    

     private javax.el.ExpressionFactory _el_expressionfactory;    
     private org.apache.AnnotationProcessor _jsp_annotationprocessor;    

     public Object getDependants() {    
         return _jspx_dependants;    
    }    

     public  void _jspInit() {    
        _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();    
        _jsp_annotationprocessor = (org.apache.AnnotationProcessor) getServletConfig().getServletContext().getAttribute(org.apache.AnnotationProcessor. class.getName());    
    }    

     public  void _jspDestroy() {    
    }    

     public  void _jspService(HttpServletRequest request, HttpServletResponse response)    
                 throws java.io.IOException, ServletException {    

        PageContext pageContext =  null;    
        HttpSession session =  null;    
        ServletContext application =  null;    
        ServletConfig config =  null;    
        JspWriter out =  null;    
        Object page =  this;    
        JspWriter _jspx_out =  null;    
        PageContext _jspx_page_context =  null;    

         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');    
            out.write('\n');    

String path = request.getContextPath();    
String basePath = request.getScheme()+ "://"+request.getServerName()+":"+request.getServerPort()+path+"/";    

            out.write("\r\n");    
            out.write("\r\n");    
            out.write("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">\r\n");    
            out.write("<html>\r\n");    
            out.write("    <head>\r\n");    
            out.write("        <base href=\"");    
            out.print(basePath);    
            out.write("\">\r\n");    
            out.write("        \r\n");    
            out.write("        <title>My JSP 'MyFirstJsp.jsp' starting page</title>\r\n");    
            out.write("        \r\n");    
            out.write("\t<meta http-equiv=\"pragma\" content=\"no-cache\">\r\n");    
            out.write("\t<meta http-equiv=\"cache-control\" content=\"no-cache\">\r\n");    
            out.write("\t<meta http-equiv=\"expires\" content=\"0\">        \r\n");    
            out.write("\t<meta http-equiv=\"keywords\" content=\"keyword1,keyword2,keyword3\">\r\n");    
            out.write("\t<meta http-equiv=\"description\" content=\"This is my page\">\r\n");    
            out.write("\t<!--\r\n");    
            out.write("\t<link rel=\"stylesheet\" type=\"text/css\" href=\"styles.css\">\r\n");    
            out.write("\t-->\r\n");    
            out.write("\r\n");    
            out.write("    </head>\r\n");    
            out.write("    \r\n");    
            out.write("    <body>\r\n");    
            out.write("    \t<h1>My First JSP!</h1>\r\n");    
            out.write("        ");    

                for(int i=0;i<10;i++){    
                        out.println(i);    
                        out.print("<br/>");    
                }    
            out.write("\r\n");    
            out.write("    </body>\r\n");    
            out.write("</html>\r\n");    
        } catch (Throwable t) {    
            if (!(t instanceof 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);    
        }    
    }    
} 
? JSP的好处 
–尽管JSP技术能够做的事情并不比servlet多，但JSP可以使下述任务更为容易： 
? 输出HTML 
? 阅读和维护这些HTML 
–JSP使得下面的做法成为可能： 
? 使用标准的HTML工具，比如Macromedia DreamWeaver或FrontPage 
? 由小组的另外一些成员完成HTML布局，不关注Java编程 
–JSP鼓励我们： 
? 将创建内容（Java）代码同表示内容的（HTML）代码分离开来
? JSP实例 
–创建一个简单的JSP页面
image
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