java连接数据库的5种方式解读

package com.hsp.edu;
 
 import com.mysql.cj.jdbc.Driver;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.util.Properties;
 
//java获取连接的5种方式
public class JdbcConnect {
    public static void main(String[] args) throws SQLException, ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        connect01();
        connect02();
 
    }
    //方式一，直接导入第三方库驱动类
    public static void connect01() throws SQLException {
 
        //获取驱动
        Driver driver = new Driver();
        //获取连接
        String url = "jdbc:mysql://localhost:3306/jdbc?serverTimezone=UTC&useSSL=false&useSer" +
                "verPrepStmts=true&characterEncoding=utf-8&useSSL=false";
        //将用户名和密码放入到Properities对象中
        Properties properties = new Properties();
        properties.setProperty("user","root");//用户
        properties.setProperty("password","888888");//密码
        final Connection connect = driver.connect(url, properties);
        System.out.println(connect);
    }
    //方式二：使用反射加载Driver：动态加载，更加的灵活，减少依赖
    public static void connect02() throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException, NoSuchMethodException, InvocationTargetException {
        //获取Driver类的字节码文件对象
        final Class<?> clazz = Class.forName("com.mysql.cj.jdbc.Driver");
        //注意：在用字节码文件对象获取Driver对象时，直接newInstance被idea提示已经弃用
        final Constructor<?> Constructor = clazz.getDeclaredConstructor();
        final Driver driver = (Driver)Constructor.newInstance();
        String url = "jdbc:mysql://localhost:3306/jdbc?serverTimezone=UTC&useSSL=false&useSer" +
                "verPrepStmts=true&characterEncoding=utf-8&useSSL=false";
        //将用户名和密码放入到Properities对象中
        Properties properties = new Properties();
        properties.setProperty("user","root");//用户
        properties.setProperty("password","888888");//密码
        final Connection connect = driver.connect(url, properties);
        System.out.println(connect);
 
    }
}
 

//方式三：使用DriverManager替换Driver
    public static void connect03() throws SQLException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchMethodException, ClassNotFoundException {
        //DriverManager类支持更好的获取连接的方法,可以直接将用户和密码作为参数，而不用存储到Properities
        final Class<?> clazz = Class.forName("com.mysql.cj.jdbc.Driver");
        final Constructor<?> constructor = clazz.getDeclaredConstructor();
        final Driver driver =(Driver)constructor.newInstance();
        //创建url和user和password
        String url = "jdbc:mysql://localhost:3306/jdbc?serverTimezone=UTC&useSSL=false&useSer" +
                "verPrepStmts=true&characterEncoding=utf-8&useSSL=false";
        String user = "root";
        final String password = "888888";
      DriverManager.registerDriver(driver);//注册Driver驱动
        final Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);
 
    }

//方式四：加载Driver时自动完成注册（这种方式使用的最多，推荐使用）
    public static void connect04() throws ClassNotFoundException, SQLException {
        //使用反射加载了Driver类
        //在加载 Driver类时，完成注册
        Class.forName("com.mysql.cj.jdbc.Driver");
        String url = "jdbc:mysql://localhost:3306/jdbc?serverTimezone=UTC&useSSL=false&useSer" +
                "verPrepStmts=true&characterEncoding=utf-8&useSSL=false";
        String user = "root";
        String password="888888";
        final Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);
 
    }

//方式五:进一步优化，将信息写入到配置文件
    public static void connect05() throws IOException, ClassNotFoundException, SQLException {
        //通过Properties对象获取配置文件信息
        Properties properties = new Properties();
        properties.load(new FileInputStream("src\\mysql.properties"));//此时已经将配置文件的信息读取到了Properties中
        //获取相关信息
        final String user = properties.getProperty("user");//用户
        final String password = properties.getProperty("password");//密码
        final String url = properties.getProperty("url");//url
        final String driver = properties.getProperty("driver");
         Class.forName(driver);//注册驱动
        final Connection connection = DriverManager.getConnection(url, user, password);//获取连接
        System.out.println(connection);
 
 
    }

package com.hsp;
 
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
 
/*
参考老师代码，使用方式5完成
1.创建news表
2.使用jdbc添加5条记录
3.修改id=1的记录content改成一个新的记录
 */
public class Jdbc02 {
    public static void main(String[] args) throws IOException, ClassNotFoundException, SQLException {
        //前置工作：获取配置文件中的信息
        Properties properties = new Properties();
        properties.load(new FileInputStream("src\\mysql1.properties"));//读取信息到集合中
        final String driver = properties.getProperty("driver");//获取全类名
        final String url = properties.getProperty("url");//获取url
        final String user = properties.getProperty("user");//获取用户名
        final String password = properties.getProperty("password");//获取密码
        System.out.println(properties);
        //1.注册驱动
      Class.forName(driver);
        //2.获取连接
        final Connection connection = DriverManager.getConnection(url, user, password);
 
        //3.执行 SQL语句
       //String sql1 = "CREATE TABLE news(id INT,content VARCHAR(32))";
       String sql2="INSERT INTO news VALUES (1,'居民健康'),(2,'商品健康'),(3,'大熊猫')";
       String sql3="UPDATE news SET content='湖北'WHERE id=1;";
        final Statement statement = connection.createStatement();
        //final int row1 = statement.executeUpdate(sql1);//返回影响的行数
        final int row2 = statement.executeUpdate(sql2);//返回影响的行数
        final int row3 = statement.executeUpdate(sql3);
 
        //：验证是否执行成功
        /*if(row1!=0){
            System.out.println("执行成功");
 
        }else {
            System.out.println("执行失败");
        }*/
        if (row2!=0){
            System.out.println("执行成功");
        }else {
            System.out.println("执行失败");
        }
        if(row3!=0){
            System.out.println("执行成功");
        }else {
            System.out.println("执行失败");
        }
 
        //4.关闭资源
        statement.close();
        connection.close();
    }
}