借助form表单向web服务器发送消息

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

 <!DOCTYPE html>

 <html>

 <head>

 <meta charset="UTF-8">

 <title>Insert title here</title>

 </head>

 <body>

 <h3>beer select</h3>

     <form method="post" action="SelectBeer.do">

     Selection beer charectar <p>

     Color:

     <select name="color" size="1">

     <option>red

     <option>blue

     <option>gray

     <option>yellow

     </select>

     <br>

     <br>

     <center>

     <input type="submit">

     </center>

     </form>

 </body>

 </html>

servlet处理的内容，此处用doPost()方法，只展示覆写的doPost()内容

 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         // TODO Auto-generated method stub

         //doGet(request, response);

         response.setContentType("text/html");

         PrintWriter out = response.getWriter();

         out.println("beer selection Adivce<br>");

         String c= request.getParameter("color");

         out.print("<br>got beer "+c);

     }

配置web.xml文件，这里是将.do的逻辑符配置给服务器

 <servlet>

     <description></description>

     <display-name>BeerSelect</display-name>

     <servlet-name>BeerSelect</servlet-name>

     <servlet-class>BeerSelect</servlet-class>

   </servlet>

   <servlet-mapping>

     <servlet-name>BeerSelect</servlet-name>

     <url-pattern>/SelectBeer.do</url-pattern>

   </servlet-mapping>

编译文件，重启tomcat服务器，得到允许结果

借助form表单向web服务器发送消息