dbconnection.java

一个用jsp完成的医院管理系统,比较适合初学者参考着学习

package hospital.db;

import java.sql.*;

/**
 * 本类用于与数据库建立接
 *
 * 作者：Fido Dido
 */
public abstract class DBConnection{
	private static Connection conn=null;

	/**
	 * 与数据库建立连接
	 *
	 * 返回值－Connection对象
	 */
	public static Connection getConnection(){
		try{
			if(conn == null){
				Class.forName("com.mysql.jdbc.Driver");
				conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/hospital","root","");
				Debug.log("Connecion created.");
			}

			else{
				Statement stmt=conn.createStatement();
				ResultSet rs=stmt.executeQuery("SELECT COUNT(*) FROM administrator");
				if(rs==null||!rs.next()){
					Class.forName("com.mysql.jdbc.Driver");
					conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/hospital","root","root");
					Debug.log("Connecion re-created.");
				}

			}
		}
		catch(Exception ex){
			Debug.log(Debug.getExceptionMsg(ex));
		}
		finally{
			return conn;
		}
	}
}