实验说明：
通过javax.servlet.http下的HttpServlet，HttpServletRequest,HttpServletResponse来完成一些常用Servlet实例
java代码部分
package com.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; public class HelloServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.log("执行了doGet方法"); execute(request,response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.log("执行了doPost方法"); execute(request,response); } public long getLastModified(HttpServletRequest request){ this.log("执行 getLastModified"); return -1; } @SuppressWarnings("unused") private void execute(HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException{ response.setCharacterEncoding("utf-8"); request.setCharacterEncoding("utf-8"); StringBuffer requestURL=request.getRequestURL();//获取页面URL String method=request.getMethod();//获取访问方法 String param=request.getParameter("param");//获取参数 response.setContentType("text/html");//设置文档类型是html PrintWriter out=response.getWriter(); out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">"); out.println("<html>"); out.println("<head><title>A Servlet</title></head><body>"); out.println("以"+method+"方式访问页面。获取的param参数为"+param+"</br>"); out.println("<form action='"+requestURL+"' method='get'>" + "<input type='text' name='param' value='param String'/>" + "<input type='submit' value='get'/></form>" + ""); out.println("<form action='"+requestURL+"' method='post'>" + "<input type='text' name='param' value='param String'/>" + "<input type='submit' value='post'/></form>" + ""); out.println("<script>document.write('本页面最后更新时间：'+document.lastModified);</script>"); out.println("</body>"); out.println("</html>"); } }
web.xml设置
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <display-name></display-name> <servlet> <servlet-name>HelloServlet</servlet-name> <servlet-class>com.servlet.HelloServlet</servlet-class> <init-param> <param-name>message</param-name> <param-value>welcome to FirstServlet!</param-value> </init-param> <init-param> <param-name>encoding</param-name> <param-value>utf-8</param-value> </init-param> <!-- 配置该Servlet的加载方式.1是tomcat启动时加载.0是第一次该方法是加载 --> <load-on-startup>1</load-on-startup> </servlet> <!-- 可以通过 /servlet/HelloServlet 或是。jsp/.php等来访问--> <servlet-mapping> <servlet-name>HelloServlet</servlet-name> <url-pattern>/servlet/HelloServlet</url-pattern> <url-pattern>/servlet/HelloServlet.jsp</url-pattern> <url-pattern>/servlet/HelloServlet.php</url-pattern> <url-pattern>/servlet/HelloServlet.aspx</url-pattern> <url-pattern>/servlet/HelloServlet.asp</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
重点code部分：
(1)用getServletConfig().getInitParameter("encoding");//来获取web.xml中的初始化数据。
（2）StringBuffer requestURL=request.getRequestURL();//获取页面URL
（3）String method=request.getMethod();//获取访问方法
（4）String param=request.getParameter("param");//获取参数