Servlet的介绍

Servlet是运行于服务端的JAVA应用程序，可以用来与数据库进行交互，响应客户请求，还可以用来生成动态的WEB页面
它一般用来后台今古代码开发，用来调用DAO或者业务逻辑层来完成数据库的操作，还可以用来接收表单参数和完成页面跳转，SERVLET的开发很简单，因为他就是一个JAVA类，唯一的不同就是要继承HTTPSERVLET这个接口。SERVLET里面三个重要的方法
doGet方法用来处理客户端的HTTP GET请求，如果客户端发送其他请求，服务器将抛出异常，处理访问表单的GET请求
doPost处理POST请求
Service同时处理GET POST
ServletTest.java

package com.soanl.servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.Date;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ServletTest extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out = response.getWriter();out.print(new Date());out.print("Hello world!");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out = response.getWriter();out.println(new Date());out.println("Hello world!");}public void service(HttpServletRequest request, HttpServletResponse response){response.setContentType("text/html;charset=UTF-8");try {PrintWriter pw = response.getWriter();pw.println("service method!");try {super.service(request,response);} catch (ServletException e) {// TODO Auto-generated catch blocke.printStackTrace();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}