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JavaWeb中Servlet和JSP的分工案例

* JSP：
> 作为请求发起页面，例如显示表单、超链接。
> 作为请求结束页面，例如显示数据。
* Servlet：
> 作为请求中处理数据的环节。

来看一张图：

下边显示一个小Demo，在一个jsp页面中输入两个参数，在另一个页面中将两者相加的结果显示。

AServlet.java

package com.ywq;

import java.io.IOException;
import java.io.PrintWriter;

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 AServlet extends HttpServlet {


	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//从form.jsp页面获取参数
		String num1=request.getParameter("num1");
		String num2=request.getParameter("num2");
		
		//参数类型转换
		int a=Integer.parseInt(num1);
		int b=Integer.parseInt(num2);
		
		int sum=a+b;
		
		//将运算结果保存在request域中
		request.setAttribute("result", sum);
		
		//请求转发，使转换到显示结果页面。
		RequestDispatcher rd=request.getRequestDispatcher("/add/result.jsp");
		rd.forward(request, response);
	}

}

form.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>这个页面用来输入两个参数</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
   <form action="/day11_1/AServlet" method="post">
   	加数1：<input type="text" name="num1"/><br>
	加数2：<input type="text" name="num2"/><br>
	<input type="submit" value="运算">
   </form>
  </body>
</html>

result.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>运算结果显示页面</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
   <%
   		Integer sum=(Integer)request.getAttribute("result");
    %>
    
    <%=sum %>
  </body>
</html>