第一周03

学习了 JavaWeb 与数据库的交互，主要使用 JDBC（Java Database Connectivity）。
首先需要加载数据库驱动，以 MySQL 为例：
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBUtil {
private static final String URL = "jdbc:mysql://localhost:3306/mydb";
private static final String USER = "root";
private static final String PASSWORD = "123456";

public static Connection getConnection() {
    Connection connection = null;
    try {
        Class.forName("com.mysql.cj.jdbc.Driver");
        connection = DriverManager.getConnection(URL, USER, PASSWORD);
    } catch (ClassNotFoundException | SQLException e) {
        e.printStackTrace();
    }
    return connection;
}

}

然后进行数据库的增删改查操作，例如查询操作：
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDao {
public void queryUser() {
Connection connection = DBUtil.getConnection();
String sql = "SELECT * FROM users";
try {
PreparedStatement preparedStatement = connection.prepareStatement(sql);
ResultSet resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {
String name = resultSet.getString("name");
int age = resultSet.getInt("age");
System.out.println("姓名：" + name + "，年龄：" + age);
}
resultSet.close();
preparedStatement.close();
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}