First JSP program (JSP Primer)

Last Update:2015-06-30 Source: Internet

Author: User

Tags apache tomcat

Developer on Alibaba Coud: Build your first app with APIs, SDKs, and tutorials on the Alibaba Cloud. Read more ＞

Create a new index.jsp file in the Web root directory

<%@ page language="java" contenttype="text/html; CHARSET=GBK "%><! 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=iso-8859-1 "><title>Insert Title here</title></head><body>Current system time<%out.println (new java.util.  Date()); %></body></html>

Configure Web. xml

<?xml version= "1.0" encoding= "UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns= "Http://java.sun.com/xml/ns/javaee" xsi:schemalocation="Http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_ 0.xsd "id=" webapp_id " version=" 3.0 ">                <welcome-file-list>        <welcome-file>index.jsp</welcome-file>    </welcome-file-list></Web-app>

Start Tomcat

Browser display output

TueJun 30 20:35:20CST 2015

View the Java class file for the JSP

Index_jsp.java files can be found in D:\apache-tomcat-7.0.62\work\Catalina\localhost\ServletStudy\org\apache\jsp, the file contents are as follows

/* * Generated by the Jasper component of Apache Tomcat * Version:apache tomcat/7.0.62 * Generated at:2015-06-30 12:        35:20 UTC * Note:the Last modified time of this file is 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 index_jsp extends org. Apache. Jasper. Runtime. Httpjspbaseimplements 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. StringJava. Lang. Long> _jspx_dependants;Private Javax. El. Expressionfactory_el_expressionfactory;private org. Apache. Tomcat. Instancemanager_jsp_instancemanager;Public Java. Util. Map<java. Lang. StringJava. 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. HttpServletRequestRequest, Final Javax. servlet. HTTP. HttpServletResponseResponse) throws Java. IO. IOException, Javax. servlet. Servletexception{//jsp Implicitly object has the following object final Javax. servlet. JSP. PageContextPageContext;Javax. servlet. HTTP. HttpSessionsession = NULL;Final Javax. servlet. ServletContextApplication;Final Javax. servlet. ServletConfigConfig;Javax. servlet. JSP. JspWriter  out= NULL;Final Java. Lang. Objectpage = This;Javax. servlet. JSP. JspWriter_jspx_out = null;Javax. servlet. JSP. PageContext_jspx_page_context = null;try {response. setContentType("text/html; CHARSET=GBK ");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("<! DOCTYPE HTML public \ "-//W3C//DTD HTML 4.01 transitional//en\" \ "http://www.w3.org/tr/html4/loose.dtd\" >\r\n ");       out. Write(");       out. Write(");       out. Write("<meta http-equiv=\" content-type\ "content=\" text/html; charset=iso-8859-1\ " >\r\n");       out. Write("<title>insert title here</title>\r\n");       out. Write(");       out. Write("<body>\r\n");       out. Write("current system time \ r \ n"); out. println(New Java. Util. Date());        out. Write("\ r \ n");       out. Write("</body>\r\n");       out. Write(");} catch (Java. Lang. ThrowableT) {if (!) ( T instanceof javax. servlet. JSP. Skippageexception)){ out= _jspx_out;if ( out! = NULL && out. GetBufferSize() !=0) try {if (response. iscommitted()) { out. Flush();} else { out. Clearbuffer();}} catch (Java. IO. IOExceptione) {} if (_jspx_page_context! = null) _jspx_page_context. Handlepageexception(t);else throw new Servletexception (t);}} finally {_jspxfactory. Releasepagecontext(_jspx_page_context);}  }}

Summarize

Org.apache.jasper.runtime.HttpJspBase implements the Javax.servlet.Servlet interface
The Index_jsp class implements the Javax.servlet.Servlet interface
As you can see, the JSP file is translated into a servlet class file by the servlet container (tomcat) and then compiled into a class file
JSP is essentially the implementation of a servlet.

First JSP program (JSP Primer)

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

Get Started for Free

Sales Support

1 on 1 presale consultation

Chat Contact Sales
After-Sales Support

24/7 Technical Support 6 Free Tickets per Quarter Faster Response

Open a Ticket
Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.

Learn More