1.Servlet Java用来创建动态WEB应用的服务器端组件,可以被部署在Java WEB服务器中,例如:Tomcat、JBoss、WebLogic等主流服务器中。Servlet可以对用户发出的请求作出响应。
2.为什么需要动态创建Web页面?
Web页面给予用户提交的 数据
例如,搜索引擎的结果和在线商店的订单确认信息
Web页面基于用户提交的数据
例如,天气预报和新闻头条
页面信息来自数据库
例如,电子商务网站的每日销售商品的价格清单
3.Servlet的功能
读取客户端发来的显示信息(表单数据)
读取客户端发来的隐式信息(请求头信息)
生成相应结果
发送显示信息给客户端(HTML)
发送隐式数据到客户端(状态码和响应头信息)
实例
.xml代码
<?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_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>week3day301</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<display-name>MyServlet</display-name>
<servlet-name>MyServlet</servlet-name>
<servlet-class>com.geek99.demo.MyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MyServlet</servlet-name>
<url-pattern>/index.jsp</url-pattern>
</servlet-mapping>
</web-app>
MyEclipse代码
package com.hp.demo;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class MyServlet
*/
public class MyServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public MyServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//HttpServletRequest request 请求
//HttpServletResponse response 响应类
PrintWriter out = response.getWriter();
out.println("Hello Servlet");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}