使用.inc 文件简化代码 JSP实现一个简单的投票功能

两个JSP页面中都使用到访问数据库的代码，我们将其封装。将数据库连接的代码专门放在一个声名当中。

1.创建一个JSP页面，将其命名为 a.inc 代码如下

<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@ 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>My JSP 'a.inc' starting page</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>
<%!
	public Connection getConnection() throws Exception{
	  	 		String DRIVER = "oracle.jdbc.driver.OracleDriver";
			String URL = "jdbc:oracle:thin:@localhost:1521:MYFIRSTORACL";
			String USER = "user1";
			String PASSWORD = "user1";
			Class.forName(DRIVER);
			Connection  conn = DriverManager.getConnection(URL,USER,PASSWORD);
			return conn;
	
	}	


 %>
 
  </body>
</html>

显示页面index.jsp

<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.Statement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
// 将a.inc导入页面
<%@ include file = "a.inc" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</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>
  	 <table align = "center">
  	 	<caption>欢迎给老师投票</caption>
  	 	<tr bgcolor ="yellow">
  	 		<td>编号</td>
  	 		<td>姓名</td>
  	 		<td>得票数</td>
  	 		<td>投票</td>
  	 	</tr>
  	 	<%
//通过getcoonection()函数获取我们封装在a.inc的COON对象
			Connection  conn = getConnection();
			Statement stat = conn.createStatement();
			String sql = "select * from tvote";
			ResultSet rs = stat.executeQuery(sql);
  	 		while(rs.next()){
  	 			String no= rs.getString("no");
  	 			String name = rs.getString("name");
  	 			int vate = rs.getInt("vate");
  	 		
  	 		
  	 	 %>
  	 	 
  	 	 <tr bgcolor="pink">
  	 	 	<td><%=no %> </td>
  	 	 	<td><%=name %> </td>
  	 	 	<td><img src ="images/a.jpg" width="<%=vate%>" height="2"><%=vate %></td>
  	 	 	<td><a href="vote.jsp?no=<%=no%>">投票</a> </td>
  	 	 </tr>
  	 	 <%
  	 	 }
  	 	 stat.close();
  	 	 conn.close();
  	 	  %>
  	 </table>
  <body>
  </body>
</html>

显示的index.jsp 与投票的vote.jsp实现了不同的功能，所以卸载不同的页面。降低了耦合性便于开发和维护

vote.jsp

  //省略了基础代码
//将a.inc导入页面
<%@ include file = "a.inc" %>

//getcooection获取到连接对象
  <body>
  <%
  			String no = request.getParameter("no");
			Connection  conn = getConnection();
			String sql = "update tvote set vate=vate+1 where no=?";
			PreparedStatement ps = conn.prepareStatement(sql);
  			ps.setString(1, no);
  			ps.executeUpdate();
  			ps.close();
  			conn.close();
  			
  
   %>
  <jsp:forward page="index.jsp"></jsp:forward>
  </body>

数据库中的创建表的代码

create table tvote (no varchar2(20),name varchar2(20), vate int);

总结，：不同的页面实现不同的功能，降低了耦合。使用.inc文件创建一个函数，对重复使用的代码进行封装，可以减少重复代码，并且便于维护。

使用.inc 文件简化代码 JSP实现一个简单的投票功能

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