我终于用RequestDispatcher实现了MVC

类别:Java 点击:0 评论:0 推荐:

1.首先建立一个html页收集输入,傻子都会,传递参数为color

 

2.然后Servlet 收集参数,并以参数通过JavaBean建立一个实例

Bean object =new Bean(color);

 

3.接着通过JavaBean的get方法返回color, Servlet 进行判断.//equals() method.

object.getColor();

 

4.servlet 判断后转到相应的jsp页面

 

String addr=...

 

核心方法:

reqest.setAttribute("Instance", object);

 

RequestDispatcher dispatcher=request.getRequestDispatcher(addr);

dispatcher .forward(request, response);

 

5.jsp 页面根据前面建立的实例读取相应的String.

<jsp:useBean  id="Instance"  type="where is bean and name" scope="request"/>

<jsp:getProperty name="Instance" property="String of getXXX() ‘s XXX ,here is String"/>

 

这个程序开始是按书上抄的,后来完全是自己写的

 

这下面的代码还不是很理解,到底建立了几个对象?那个是实例?特别是setAttribute("Red", color);

里是用前面的替换后边的吗?

 

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

 ColorBean color=new ColorBean(tempColor);

 

request.setAttribute("Red", color);
 RequestDispatcher dispatcher=request.getRequestDispatcher(addr);

 dispatcher.forward(request, response);

 

现在可以实现mvc架构了,但是,其中对象的产生过程还是不理解,对象啊,对象......

 

下边是源代码:

 

其中

Input.jsp 为收集颜色(string)页面

WantColor.java 为servlet

ColorBean.java 为JavaBean

其它的是三个jsp 页面用来连接javaBean 显示颜色

   

越来觉得老外的书经典了,为什么我不是美国人呢?

 

***********
//input.jsp


<%@ page contentType="text/html;charset=GB2312"%>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=GB2312">
    <title>请输入你想要的颜色</title>
  </head>
 
 
  <body>
  <form action="./servlet/WantColors" type=post>
  <input type=text name=color>
  <input type=submit value=submit>
 
  </form>
 
 
  </body>




</html>
**************
//wantColors.java
package moonsoft.test.j2ee.wantColors;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.PrintWriter;
import java.io.IOException;

public class WantColors extends HttpServlet
{
  private static final String CONTENT_TYPE = "text/html; charset=Big5";

  public void init(ServletConfig config) throws ServletException
  {
    super.init(config);
  }

  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {
    String tempColor=request.getParameter("color");
   ColorBean color=new ColorBean(tempColor);
    if((color.getColor()==null)&&(color.getColor()).equals(""))
    {
      addr="../input.jsp";
      response.sendRedirect("");
    }
    else if(color.getColor().equals("red"))
    {
      request.setAttribute("Red", color);
      addr="../red.jsp";
    }
    else if(color.getColor().equals("green"))
    {
      request.setAttribute("Green",color );
      addr="../green.jsp";
    }
    else
    {
      request.setAttribute("Blue",color );
      addr="../blue.jsp";
    }
    RequestDispatcher dispatcher=request.getRequestDispatcher(addr);
    dispatcher.forward(request, response);
   
   
   
    /*response.setContentType(CONTENT_TYPE);
    PrintWriter out = response.getWriter();
    out.println("<html>");
    out.println("<head><title>WantColors</title></head>");
    out.println("<body>");
    out.println("<p>The servlet has received a GET. This is the reply.</p>");
    out.println("</body></html>");
    out.close();*/
  }

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {
   
    doGet(request, response);
   
    /*response.setContentType(CONTENT_TYPE);
    PrintWriter out = response.getWriter();
    out.println("<html>");
    out.println("<head><title>WantColors</title></head>");
    out.println("<body>");
    out.println("<p>The servlet has received a POST. This is the reply.</p>");
    out.println("</body></html>");
    out.close();*/
  }
  private String addr;
}
***********************

//ColorBean.java

package moonsoft.test.j2ee.wantColors;

public class ColorBean
{
  public ColorBean(String color)
  {
  this.color=color;
  }
  public String getString()
  {
    String s="The color is  :\t";
    return s+color;
   
  }
  public String  getColor()
  {
    return color;
  }
  public void setColor(String color)
  {
    this.color=color;
  }
  private String color;
}

**************
red.jsp

<%@ page contentType="text/html;charset=Big5"%>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=Big5">
    <title>red</title>
  </head>
 
 
  <body bgcolor="#FF0000">
  <font color="#ffffff" size=6>
 
  <jsp:useBean id="Red" type="moonsoft.test.j2ee.wantColors.ColorBean" scope="request"/>
  <jsp:getProperty name="Red" property="String"/>
 
  </font>
  </body>
</html>


那两个绿色和蓝色的copy 一下,然后改一下值就好了

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