form表单是常用的，在网页浏览器中 用户点击的请求经htto协议发送回web容器，请求处理
建立用户的页面
1 <!DOCTYPE html> 2 <html> 3 <head> 4 <meta charset="UTF-8"> 5 <title>Insert title here</title> 6 </head> 7 <body> 8 <h3>beer select</h3> 9 <form method="post" action="SelectBeer.do"> 10 Selection beer charectar <p> 11 Color: 12 <select name="color" size="1"> 13 <option>red 14 <option>blue 15 <option>gray 16 <option>yellow 17 </select> 18 <br> 19 <br> 20 <center> 21 <input type="submit"> 22 </center> 23 </form> 24 </body> 25 </html>
servlet处理的内容，此处用doPost()方法，只展示覆写的doPost()内容
1 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 2 // TODO Auto-generated method stub 3 //doGet(request, response); 4 response.setContentType("text/html"); 5 PrintWriter out = response.getWriter(); 6 out.println("beer selection Adivce<br>"); 7 String c= request.getParameter("color"); 8 out.print("<br>got beer "+c); 9 }
配置web.xml文件，这里是将.do的逻辑符配置给服务器
1 <servlet> 2 <description></description> 3 <display-name>BeerSelect</display-name> 4 <servlet-name>BeerSelect</servlet-name> 5 <servlet-class>BeerSelect</servlet-class> 6 </servlet> 7 <servlet-mapping> 8 <servlet-name>BeerSelect</servlet-name> 9 <url-pattern>/SelectBeer.do</url-pattern> 10 </servlet-mapping>
编译文件，重启tomcat服务器，得到允许结果
