Java如何编写Servlet程序

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一：Servlet

Servlet是Java服务器端编程，不同于一般的Java应用程序，Servlet程序是运行在服务器上的，服务器有很多种，Tomcat只是其中一种。

例子：

在Eclipse中新建一个Web

在src中新建一个包，其中新建一个类叫 XXXXServlet

编写Servlet程序如下：

package com.sally.servlet; import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date; import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; /**
* Servlet implementation class HelloWorldServlet
*/
@WebServlet("/HelloWorldServlet")
public class HelloWorldServlet extends HttpServlet {
private static final long serialVersionUID = 1L; /**
* @see HttpServlet#HttpServlet()
*/
public HelloWorldServlet() {
super();
// TODO Auto-generated constructor stub
} /**
* @see Servlet#init(ServletConfig)
*/
public void init(ServletConfig config) throws ServletException { } /**
* @see Servlet#destroy()
*/
public void destroy() { } /**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
@SuppressWarnings("deprecation")
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><head><title>Hello World Sample</title></head>");
out.println("<body><h1>Hello World Title<h1><h2>" +new Date().toLocaleString() + "</h2></body></html>");
out.flush();
} /**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("进入"+ this.getClass().getName());
} }

Servlet程序没有main方法，类一般都需要继承HttpServlet类。

二：web.xml

打开web.xml，编写内容如下：

<?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">
<servlet>
<servlet-name>HelloWorldServletName</servlet-name>
<servlet-class>com.sally.servlet.HelloWorldServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorldServletName</servlet-name> 
<url-pattern>/HelloWorld</url-pattern>
</servlet-mapping>
</web-app>