基于表单的投票系统--MySql ,DAO ,VO

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基于表单的投票系统--MySql ,DAO ,VO_MySQL

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Jun 01, 2016 pm 01:09 PM

一。系统分析

只要一个界面，但是建议写两个，一个用于显示投票界面，一个用于接受用户的投票，将所对应的老师得票加1 ，

工作完了再回到前一个界面。

各个页面与作用：

VoteDao.java 连接数据库，查询老师的编号，姓名，得票，修改老师的得票数，将编号对应的得票数加 1

Vote.java 封装老师的编号，姓名，得票数

display.jsp 调用VoteDao查询老师编号，姓名，得票数，并显示

vote.jsp 获得request 传送过来的老师编号数组，调用 VoteDao 将每个编号对应的得票数加1 ，回到display.jsp

二。数据库初始化

属性：teacherno teachername votenumber

在mySQL中写成脚本运行，用source 命令。

use test;create table t_vote( teacherno varchar(20), teachername varchar(20), vote int );insert into t_vote values('1', 'lishengjing',1);insert into t_vote values('2', 'huangwenjun',1);insert into t_vote values('3', 'zhaosy',2);insert into t_vote values('4', 'chaoshehn',3);

三。java 代码

要将MySQL的驱动复制到 web-inf/lib中，将bar.jpg 复制到WebRoot下的img目录。导入包时最好用 import java.sql*;

public class VoteDao {	private Connection  conn=null;		public void initConnection() throws Exception{		Class.forName("com.mysql.jdbc.Driver");		String url ="jdbc:mysql://localhost:3306/test";		conn = DriverManager.getConnection(url , "root","root");			}		public ArrayList getAllVotes()throws Exception{		ArrayList all = new ArrayList ();		initConnection();		String sql = "select * from t_vote";		Statement stat= conn.createStatement();		ResultSet rs = stat.executeQuery(sql);				while (rs.next()){			Vote vote = new Vote();			vote.setTeacherno(rs.getString("teacherno"));			vote.setTeachername(rs.getString("teachername"));			vote.setVotenumber(rs.getInt("vote"));			all.add(vote);		}		clossConnection();		return all;			}		public void updateVotes(String [] teacherno )throws Exception{		initConnection();		String sql = "update t_vote set vote=vote+1 where teacherno=?";		PreparedStatement ps = conn.prepareStatement(sql);				for (int i =0;i<teacherno.length;i++){			ps.setString(1, teacherno[i]);			ps.executeUpdate();		}		clossConnection();	}		public void clossConnection ()throws Exception{		conn.close();	}}

四。JSP代码部分

display.jsp

<body>    <form action ="vote.jsp"  method ="post">		<table align="center">			<caption>				欢迎投票<input type="submit" value="提交">			</caption>			<tr bgcolor="yellow">				<td>编号</td>				<td>姓名</td>				<td>得票数</td>			</tr>			<%				VoteDao vdao= new VoteDao();			    ArrayList votes = vdao.getAllVotes();			    for (int i=0;i<votes.size();i++){			    Vote vote =(Vote) votes.get(i);			%>			<tr bgcolor="pink">				<td><%=vote.getTeacherno()%></td>				<td><%=vote.getTeachername()%></td>				<td><img  src ="img/bar.jpg"     style="max-width:90%"基于表单的投票系统--MySql ,DAO ,VO_MySQL" >"  height ="10"/>				<%=vote.getVotenumber() %></td>				<td><input name="teacherno" type="checkbox"					value="<%=vote.getTeacherno()%>"></td>			</tr>			<%				}			%>		</table>	</form>  </body>

vote,jsp

 <body>    <%     String [] teacherno = request.getParameterValues("teacherno") ;    VoteDao vdao = new VoteDao();    vdao.updateVotes(teacherno);    %>    <jsp:forward page="display.jsp"></jsp:forward>  </body>

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