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| The Servlet Container makes a JSP work by converting it into a servlet. So, everything you learned about servlets is still relevant for JSPs. For our very simple example: <!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=UTF-8">
<title>A Simple JSP</title>
</head>
<body>
<h1>Greetings!</h1>
<p>This is a 'Hello!' from <i><%= request.getParameter("name") %></i>.</p>
<p>How are you today?</p>
</body>
</html>
This is the corresponding generated servlet code (as generated by the built-in Tomcat server container that comes with NetBeans 5.5): package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
public final class SimpleJSP_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent {
private static java.util.List _jspx_dependants;
public Object 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;
PageContext _jspx_page_context = null;
try {
_jspxFactory = JspFactory.getDefaultFactory();
response.setContentType("text/html");
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("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\"\n");
out.write(" \"http://www.w3.org/TR/html4/loose.dtd\">\n");
out.write("\n");
out.write("<html>\n");
out.write(" <head>\n");
out.write(" <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">\n");
out.write(" <title>A Simple JSP</title>\n");
out.write(" </head>\n");
out.write(" <body>\n");
out.write("\n");
out.write(" <h1>Greetings!</h1>\n");
out.write(" <p>This is a 'Hello!' from <i>");
out.print( request.getParameter("name") );
out.write("</i>.</p>\n");
out.write(" <p>How are you today?</p>\n");
out.write(" \n");
out.write(" </body>\n");
out.write("</html>\n");
} catch (Throwable t) {
if (!(t instanceof SkipPageException)){
out = _jspx_out;
if (out != null && out.getBufferSize() != 0)
out.clearBuffer();
if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
}
} finally {
if (_jspxFactory != null) _jspxFactory.releasePageContext(_jspx_page_context);
}
}
}
Note how the straight HTML from the JSP is output directly using a series of out.write() calls, while the contents of the JSP tag (here, a Java expression) is extracted, and also placed in an out.write() call. |
| The page was last updated February 19, 2008 |