//单态设计模式的JDBC
package com.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
/**
 * JDBC
 * @author Administrator
 *
 */
public class DbUtil {
	private static DbUtil db=new DbUtil();
	private final String URL="jdbc:mysql://localhost:3306/Librarymanagement";
	private final String NAME="root";
	private final String PASSWORD="123456";
	
	/**
	 * 注册驱动
	 */
	private DbUtil(){
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			System.out.println("注册驱动失败");
		}
	}
	/**
	 * 得到db链接数据库
	 * @return
	 */
	public static DbUtil getDb() {
		return db;
	}
	
	/**
	 * 链接数据库
	 * @return
	 */
	public Connection getConn(){
		Connection con=null;
		try {
			con=DriverManager.getConnection(URL,NAME,PASSWORD);
			System.out.println("ok-ok-lianjie");
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}//链接数据库
	
		return con;
	}
	
	/**
	 * 关闭数据库
	 * @param obj
	 */
	public void closeDb(Object obj){
		try {
			if(obj instanceof ResultSet){
				ResultSet th=(ResultSet)obj;
			
					th.close();
			}else if(obj instanceof Statement){
				Statement st=(Statement)obj;
				
				st.close();
			}else if(obj instanceof Connection){
				Connection con=(Connection)obj;
				
				con.close();
			}
		} catch (SQLException e) {
				// TODO Auto-generated catch block
				System.out.println("关闭失败");
		}
		
	}
	
}