JDBC 1

来源：互联网发布：淘宝购物评级优秀编辑：程序博客网时间：2024/06/05 15:04

JDBC

一.Connection工具类

1.接口DBSource.java

//DBSource.java
package chapter20;

import java.sql.Connection;
import java.sql.SQLException;

public interface DBSource {
public Connection getConnection() throws SQLException;
public void closeConnection(Connection conn) throws SQLException;
}

2.你的目的是从属性文件中读取设置信息，加载JDBC驱动程序，可通过getConnection()方法获得Connection对象，并通过closeConnection()方法关闭Connection对象

//SimpleDBSource.java
package chapter20;

import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import java.io.FileInputStream;
import java.sql.DriverManager;

public class SimpleDBSource implements DBSource {
    private Properties props;
    private String url;
    private String user;
    private String password;



    public SimpleDBSource() throws IOException,
                            ClassNotFoundException{
        props = new Properties();
        String configFile = null;
        props.load(new FileInputStream(configFile));

        url = props.getProperty("chapter19.url");
        user = props.getProperty("chapter19.user");
        password = props.getProperty("chapter19.password");

        Class.forName(props.getProperty("chapter19.driver"));

    }
    @Override
    public void closeConnection(Connection conn) throws SQLException {
        conn.close();
    }

    @Override
    public Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url,user,password);
    }

}

默认的构造函数读取jdbc.properties文件中的设置

//jdbc.properties
chapter20.driver = com.mysql.jdbc.Driver;
chapter20.url = jdbc:mysql://localhost:3306/demo
chapter20.user = root
chapter20.password = 123456

3.测试SimpleDBSource是否可以正确获得与数据库的连接

//ConnectionDemo.java
package chapter20;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;

public class ConnectionDemo {

    /**
    * @param args
    */
    public static void main(String[] args) {
        try{
            DBSource dbsource = new SimpleDBSource();
            Connection conn = dbsource.getConnection();
            if(!conn.isClosed()){
                System.out.println("数据库连接已经开启");
            }

            dbsource.closeConnection(conn);

            if(conn.isClosed()){
                System.out.println("数据库连接已经关闭");
            }
        }
        catch(SQLException e){
            e.printStackTrace();
        }
        catch(IOException e){
            e.printStackTrace();
        }
        catch(ClassNotFoundException e){
            e.printStackTrace();
        }

    }

}