使用单例模式创建DBConnection

package com.singleton;

import java.sql.Connection;
import java.sql.DriverManager;

public class DBConnection {
	private static DBConnection dbc;
	private String url="jdbc:sqlserver://10.10.0.98:1433;databaseName=mydb";  
	private String user="username";  
	private String password="password";
	private Connection conn;
    //私有构造器,只允许内部实用,不允许在外面调用创建类实例
	private DBConnection(){
		
	}
	public static DBConnection getInstance(){
		if (dbc == null) {
			dbc = new DBConnection();
		}
		return dbc;
	}
	
	public Connection getConnection(){
		try {
			Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); 
			if (conn == null){
				conn= DriverManager.getConnection(url,user,password);
			}		 
		}
		catch (Exception e){
			e.printStackTrace();		
		}	
		return conn;	
	}

}