dao.java

地址薄

package javabean;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Dao {
	private String driverName="com.microsoft.jdbc.sqlserver.SQLServerDriver";
	private String userName="sa";
	private String userPwd="";
	
	private String dbName="test";
//	jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=test;User=sa;Password=pwd
	private String url="jdbc:microsoft:sqlserver://localhost:1433;DataBaseName="+
	dbName+";User="+userName+";Password="+userPwd;
	
	private Connection conn=null;
	private  Statement sm=null;
	private  static Dao dao;
    public Dao()
    {
    }
    

    public static Dao Instance()
    {
       if (dao == null)
           dao = new Dao();
       return dao;        
    }
    
	public void ConnectDB()
	{
		try {
			Class.forName(driverName).newInstance();
			conn=DriverManager.getConnection(url);
			sm=conn.createStatement();
//			System.out.print("数据库连接成功");
		} catch (InstantiationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch(SQLException e)
		{
			e.printStackTrace();
//			System.out.print("数据库连接失败");
		}
		
		
	}
	
	public void CloseDB()
	{
		try {
	        if(sm!=null)
	        {
	        	sm.close();
	        	
	        }
	        conn.close();
		}
		catch(SQLException e)
		{
			e.printStackTrace();
//			System.out.print("数据库关闭失败");
		}
	}
	
	/*
	  返回sql执行的结果，发生异常返回-2
	 * 
	 */
	public int executeUpdate(String sql)
	{
		int i;
        ConnectDB();		
		try {
			i=sm.executeUpdate(sql);
			return i;
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return -2;
		} finally {
			CloseDB();
		}
	}
	
	public ResultSet executeQuery(String sql)
	{
		ConnectDB();
		ResultSet rs=null;
		try
		{
			rs=sm.executeQuery(sql);
			return rs;
		}
		catch(SQLException sqle)
		{
			sqle.printStackTrace();
			return null;
		}
		catch(Exception e)
		{
			e.printStackTrace();
			return null;
		}
		finally
		{
	//		CloseDB();
		}
	}
	

}