JDBC完整流程

得到了:


1)加载驱动
采用反射方式加载驱动

https://www.bilibili.com/video/BV12b411K7Zu?p=310

考虑到很多重复的用户名,密码,com.mysql.jdbc.Driver,等多次需要输入,将它们写入配置文件中,简化操作,通过一个集合Propertie装起来,用的时候取出来即可.
在src目录下新建文件jdbc.properties:

从集合Propertie中取出信息进行加载和连接
2)获取连接

https://www.bilibili.com/video/BV12b411K7Zu?p=311
利用连接获取sql的命令对象. connection.createStatement();

其中,set里面就像装了一张表似的.
ResultSet集合 set最开始指向表头,set.next()指向第一行数据.
set.getInt(1)表示获得第一列和set目前指向的行对应的数据,也可以用set.getint(“列名”)和set目前指向的行对应的数据.
当不知道是什么数据类型时可以选择set.getObject(列号)或者set.getObject(“列名”)来获得对应的数据.
https://www.bilibili.com/video/BV12b411K7Zu?p=312

package com.atguigu.jdbc;
//老师的代码
import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Properties;
/**
 * 此类用于演示JDBC的使用步骤3：增删改查
 * 
 * @author liyuting
 *
 */
public class TestJDBC3 {
    public static void main(String[] args) throws Exception {
        Properties info  = new Properties();
        info.load(new FileInputStream("src\\jdbc.properties"));
        String user = info.getProperty("user");
        String password = info.getProperty("password");
        String driver = info.getProperty("driver");
        String url = info.getProperty("url");
        //1.注册驱动
        Class.forName(driver);
        //2.获取连接
        Connection connection = DriverManager.getConnection(url, user, password);
        //3.执行增删改查
        //①编写sql命令
//        String sql = "select id,name,sex,borndate from beauty";
        //②获取执行sql的命令对象
        Statement statement = connection.createStatement();
        //③执行sql语句
//        boolean execute = statement.execute(sql);//执行任何sql语句
//        int update = statement.executeUpdate(sql);//执行增删改语句，返回受影响的行数
        ResultSet set = statement.executeQuery( "select id,name,sex,borndate from beauty");//执行查询语句，返回一个结果集
        //④处理执行后的结果
        while(set.next()){
            int id = set.getInt(1);
            String name = set.getString(2);
            String sex = set.getString(3);
            Date date = set.getDate(4);
            System.out.println(id+"\t"+name+"\t"+sex+"\t"+date);
        }
        //4.关闭连接
        set.close();
        statement.close();
        connection.close();
    }
}

package com.atguigu.jdbc;
//我执行的代码
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;

public class TestJdbc3 {
    public static void main(String[] args) throws ClassNotFoundException, FileNotFoundException, IOException, SQLException {
        Properties info = new Properties();
        info.load(new FileInputStream("src\\jdbc.properties"));
        String user = info.getProperty("user");
        String password = info.getProperty("password");
        String url = info.getProperty("url");
        String driver = info.getProperty("driver");
        //注册驱动
        Class.forName(driver);
        //获得连接
        Connection connection=(Connection) DriverManager.getConnection(url, user, password);
        //System.out.println("注册成功");

        //数据库操作
        String sql1="select id,name,sex,borndate from beauty";
        //利用连接获取执行sql的命令对象,
        Statement statement = (Statement) connection.createStatement();
        //执行sql1语句,返回收到影响的行数
        //int update = statement.executeUpdate(sql1);
        ResultSet set = statement.executeQuery(sql1);

        while(set.next()) {
            int id = (int)set.getObject("id");
            String name = (String)set.getObject("name");
            String sex = (String)set.getObject("sex");
            Date date = (Date)set.getDate("borndate");
            System.out.println(id+"\t"+name+"\t"+sex+"\t"+date);
        }

        //关闭连接
        set.close();
        statement.close();
        connection.close();

    }
}

https://www.bilibili.com/video/BV12b411K7Zu?p=309