votebean.java

网上书店

package com.bitc.store;
//定义Bean所属的套件

//定义欲使用的套件
import java.sql.*;

public class VoteBean
{
	//与资料库连结有关的Bean属性
	private Connection con = null;
	private Statement stmt = null;
	private ResultSet BookRs = null;

	public VoteBean()  //建构子
	{		
	}	

	//以下为设定Bean属性的方法
	public void InitBookRs(Connection con)
	{
		try{			
			this.con = con; //设定con物件			
			
			stmt = this.con.createStatement(
					ResultSet.TYPE_SCROLL_INSENSITIVE,
					ResultSet.CONCUR_READ_ONLY);
			//建立Statement物件			

			BookRs = stmt.executeQuery
				 ("SELECT ID, BookID, BookNm FROM Book");			
			//执行SQL叙述, 从Book资料表中取得栏位
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}		
	}

	//关闭Restult物件与Statement物件
	public void CloseBookRs ()
	{ 
		try{
			if(BookRs != null)			
			{
				BookRs.close();
				BookRs = null;
			}

			if(stmt != null)			
			{
				stmt.close();
				stmt = null;
			}
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}
	}

	//移至将ResultSet物件的指标移至下一笔记录
	public boolean next()
	{ 
		boolean result = false;
		try{
			result = BookRs.next();
			//移至下一笔记录
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}		
		return result;
	}
	
	//取得ResultSet物件ID栏位的资料
	public String getID()
	{ 
		String result = null;
		try{
			result = BookRs.getString("ID");
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}		
		return result;
	}

	//取得ResultSet物件BookID栏位的资料
	public String getBookID()
	{ 
		String result = null;
		try{
			result = BookRs.getString("BookID");
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}		
		return result;
	}

	//取得ResultSet物件BookNm栏位的资料
	public String getBookNm()
	{ 
		String result = null;
		try{
			result = BookRs.getString("BookNm");
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}		
		return result;
	}

	//将投票结果新增至资料库
	public void InsertChoice(Connection con, String choice)
	{ 
		int affect = 0;
				
		String strSQL = "INSERT INTO Vote(choice) VALUES (" +
				choice + ")";
		//建立将资料新增至资料库的SQL叙述
		
		try{
			this.con = con; //设定con物件			
			
			stmt = this.con.createStatement(
					ResultSet.TYPE_SCROLL_INSENSITIVE,
					ResultSet.CONCUR_READ_ONLY);
			//建立Statement物件	
			stmt.executeUpdate(strSQL);
			//执行SQL叙述
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}
	}

	//取得投票给某书记录笔数
	public int VoteNum(Connection con, String filter)
	{
		String strSQL = "SELECT ID FROM Vote";		
		int num = 0;		

		//判断传入的filter字串是否为空字串, 
		//是则将筛选条件增加至SQL叙述
		if(!filter.equals(""))
			strSQL = strSQL + " WHERE " + filter;		
		
		try{
			this.con = con;
			Statement lstmt = null;	
			lstmt = this.con.createStatement(
					ResultSet.TYPE_SCROLL_INSENSITIVE,
					ResultSet.CONCUR_READ_ONLY);
			//建立Statement物件

			ResultSet rs = lstmt.executeQuery(strSQL);
			//执行SQL叙述
			
			rs.last(); //移至最後一笔记录
			
			num =  rs.getRow(); //取得记录的笔数
			
			rs.close();
			lstmt.close();			
		}
		catch(SQLException sex)
		{
			System.out.println(sex.toString());
		}

		return num;
	}	
}