用Android studio写连接MySQL的Java类

首先需要在Android Studio中添加MySQL JDBC驱动库，可以在build.gradle文件中添加以下依赖：

dependencies {
    // ...
    implementation 'mysql:mysql-connector-java:8.0.23'
}

然后可以创建一个名为MySQLConnector的Java类，用于连接MySQL数据库和执行查询操作。代码如下：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class MySQLConnector {
    private Connection connection;
    private Statement statement;
    private ResultSet resultSet;

    // 连接MySQL数据库
    public void connect() throws SQLException {
        String url = "jdbc:mysql://localhost:3306/db_name";
        String user = "username";
        String password = "password";
        connection = DriverManager.getConnection(url, user, password);
    }

    // 执行查询操作
    public ResultSet executeQuery(String sql) throws SQLException {
        statement = connection.createStatement();
        resultSet = statement.executeQuery(sql);
        return resultSet;
    }

    // 关闭连接
    public void close() throws SQLException {
        if (resultSet != null) {
            resultSet.close();
        }
        if (statement != null) {
            statement.close();
        }
        if (connection != null) {
            connection.close();
        }
    }
}

其中connect方法用于连接MySQL数据库，executeQuery方法用于执行查询操作，close方法用于关闭连接。

使用示例：

MySQLConnector connector = new MySQLConnector();
try {
    connector.connect();
    ResultSet resultSet = connector.executeQuery("SELECT * FROM table_name");
    while (resultSet.next()) {
        int id = resultSet.getInt("id");
        String name = resultSet.getString("name");
        // ...
    }
} catch (SQLException e) {
    e.printStackTrace();
} finally {
    try {
        connector.close();
    } catch (SQLException e) {
        e.printStackTrace();
    }
}