jsp研究（一）
來源：互聯網
上載者：User
js 用jsp開發了程式好些時間了，但感覺對jsp的掌握還是不夠。現在先分析一下*.jsp檔案編譯後的*_jsp.java 檔案。
先寫一個簡單的my.jsp檔案如下：
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>baiming</title>
</head>
<body>
hello
</body>
</html>
****************************************************************
把改檔案方到 tomcat根目錄\webapps\ROOT 下。
運行tomcat，在地址欄裡輸入http://localhost:8080/my.jsp
在 tomcat根目錄\work\Catalina\localhost\_\org\apache\jsp 下就會產生my_jsp.java檔案。
我們現在來看看這個檔案：
package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import java.sql.*;
public final class my_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent {
private static java.util.Vector _jspx_dependants;
public java.util.List getDependants() {
return _jspx_dependants;
}
public void _jspService(HttpServletRequest request, HttpServletResponse response)
throws java.io.IOException, ServletException {
JspFactory _jspxFactory = null;
PageContext pageContext = null;
HttpSession session = null;
ServletContext application = null;
ServletConfig config = null;
JspWriter out = null;
Object page = this;
JspWriter _jspx_out = null;
try {
_jspxFactory = JspFactory.getDefaultFactory();
response.setContentType("text/html; charset=gb2312");
pageContext = _jspxFactory.getPageContext(this, request, response,
"", true, 8192, true);
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();
_jspx_out = out;
out.write("\r\n");
out.write("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n");
out.write("<html>\r\n");
out.write("<head>\r\n");
out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=gb2312\">\r\n");
out.write("<title>baiming</title>\r\n");
out.write("</head>\r\n");
out.write("\r\n");
out.write("<body>\r\n");
out.write("hello\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)
out.clearBuffer();
if (pageContext != null) pageContext.handlePageException(t);
}
} finally {
if (_jspxFactory != null) _jspxFactory.releasePageContext(pageContext);
}
}
}
你會發現jsp裡使用的8個隱含的對象。
