Servlet基础笔记_17-07-04

Servlet

1.servlet是一种web服务器端编程技术

2.servlet是继承了javax、servlet、http.HttpServlet类的Java类

3.servlet由支持servlet的web服务器（tomcat）调用和启动运行

4.一个servlet负责对应的一个或一组URL访问，并返回相应的响应内容

浏览器通过URL来访问服务器

Servlet是一种类

写Servlet步骤：

1.创建一个类 extends javax.servlet.http.HttpServlet

2.重写三个方法：

public void init() throws ServletException

protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException

public void destroy() 

3.给servlet配备一个URL地址，供浏览器访问servlet用

打开WebRoot/WEB-INF/web.xml文件，添加<servlet>标签和<servlet-mapping>标签

例子：

FirstServletcom.yy.servlet.web.servlet.FirstServletFirstServlet/tangjiawei

emptypackage com.yy.servlet.web.servlet;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;import javax.xml.ws.Response;public class FirstServlet extends HttpServlet{@Override public void init() throws ServletException{super.init();System.out.println("初始化");}@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {System.out.println("正在");//接受参数String username = req.getParameter("username");String password = req.getParameter("password");//返回参数resp.setCharacterEncoding("UTF-8");resp.setContentType("text/html");PrintWriter out = resp.getWriter();out.print("servlet返回的" + username);out.print("servlet返回的" + password);out.flush();out.close();}@Overridepublic void destroy() {super.destroy();System.out.println("被摧毁");}}