Mini MVC

创建和部署MVC Web应用：

HTML表单、servlet控制器、模型（java类）、XML部署文件、JSP视图

第一步：构建用户最初请求的HTML表单

< html >
< body >
< h1 align ="center" >
Beer Selection Page
</h1>
< form method ="post" action ="SelectBeer.do" >
  Select beer characteristics < p >
  Color:
   < select name ="color" size ="1" >
     < option >light
     < option >amber
     < option >brown
     < option >dark
   </select>
   < br > < br >
   < center >
     < input type ="submit" >
   </center>
</form>
</body>
</html>

第二步：创建模型BeerExpert

package com.zyun.model;

import java.util.*;

public class BeerExpert {
   public List getBrands(String color){
    List brands = new ArrayList();
     if(color.equals( "amber")){
      brands.add( "Jack Amber");
      brands.add( "Red moose");
    }
     else{
      brands.add( "Jail Pale Ale");
      brands.add( "Gout Stout");
    }
     return (brands);
  }
}

第三步：创建控制器BeerSelect

package com.zyun.web;

import java.io.IOException;
import java.util.List;

import com.zyun.model.BeerExpert;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class BeerSelect extends HttpServlet {
   public void doPost(HttpServletRequest request, HttpServletResponse response)
       throws IOException, ServletException {
    String c = request.getParameter( "color");
    BeerExpert be = new BeerExpert();
    List result = be.getBrands(c);
    request.setAttribute( "styles", result);
    RequestDispatcher view = request.getRequestDispatcher( "result.jsp");
    view.forward(request, response);
  }
}

第四步：创建视图result.jsp

< %@ page import ="java.util.*"% >
< html >
< body >
< h1 aglin ="center" >Beer Recommendations JSP < h1 >
< p >

<%
  List styles = (List)request.getAttribute("styles");
  Iterator it = styles.iterator();
  while(it.hasNext()){
  out.println(" < br >try: "+it.next());
  }
%>
</boyd>
</html>

第五步：部署描述文件（web.xml）

<? xml version ="1.0" encoding ="ISO-8859-1" ?>
< web-app 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"
         version ="2.5" >
         < servlet >
           < servlet-name >Beer </ servlet-name >
           < servlet-class >com.zyun.web.BeerSelect </ servlet-class >
         </ servlet >
         < servlet-mapping >
           < servlet-name >Beer </ servlet-name >
           < url-pattern >/SelectBeer.do </ url-pattern >
         </ servlet-mapping >
</ web-app >

整个MVC应用的执行过程: