package myjava;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public final class JdbcUtils//不允许继承

{

private static String url = "jdbc:mysql://localhost:3306/demo";//连接地址

private static String user = "root";//用户名

private static String password = "root";//密码

private JdbcUtils(){};//禁止创建对象不允许继承

static//静态代码块，保证了驱动只注册一次

{

try

{

Class.forName("com.mysql.jdbc.Driver");

}

catch(ClassNotFoundException e)

{

throw new ExceptionInInitializerError(e);

}

}

public static Connection getConnection() throws SQLException//获取建立了连接的对象

{

return DriverManager.getConnection(url,user,password);

}

public static void free(ResultSet rs,Statement st,Connection conn)//关闭资源

{

try

{

if(rs != null)

{

rs.close();

}

}

catch(SQLException e)

{

e.printStackTrace();

}

finally

{

try

{

if(st != null)

{

st.close();

}

}

catch(SQLException e)

{

e.printStackTrace();

}

finally

{

if(conn!=null)

{

try

{

conn.close();

} catch (SQLException e)

{

e.printStackTrace();

}

}

}

}

}

}