安卓连mysql数据库的方式

dependencies {
    implementation 'mysql:mysql-connector-java:8.0.26'
}

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

public class MainActivity extends AppCompatActivity {
    private static final String DB_URL = "jdbc:mysql://<MySQL服务器地址>:<端口号>/<数据库名称>";
    private static final String DB_USER = "<用户名>";
    private static final String DB_PASSWORD = "<密码>";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
            stmt = conn.createStatement();
            String sql = "SELECT * FROM <表名>";
            rs = stmt.executeQuery(sql);
            
            while (rs.next()) {
                String column1 = rs.getString("column1");
                String column2 = rs.getString("column2");
                // 处理查询结果
            }
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null) {
                    rs.close();
                }
                if (stmt != null) {
                    stmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

<?php
$servername = "<MySQL服务器地址>";
$username = "<用户名>";
$password = "<密码>";
$dbname = "<数据库名称>";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

$sql = "SELECT * FROM <表名>";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        $column1 = $row["column1"];
        $column2 = $row["column2"];
        // 处理查询结果
    }
} else {
    echo "0 结果";
}

$conn->close();
?>

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends AppCompatActivity {
    private static final String PHP_SCRIPT_URL = "<PHP脚本的URL>";

    private TextView resultTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        resultTextView = findViewById(R.id.result_text_view);

        new FetchDataAsyncTask().execute();
    }

    private class FetchDataAsyncTask extends AsyncTask<Void, Void, String> {
        @Override
        protected String doInBackground(Void... voids) {
            StringBuilder result = new StringBuilder();

            try {
                URL url = new URL(PHP_SCRIPT_URL);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("GET");

                BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line;
                while ((line = reader.readLine()) != null) {
                    result.append(line);
                }
                reader.close();
            } catch (Exception e) {
                e.printStackTrace();
            }

            return result.toString();
        }

        @Override
        protected void onPostExecute(String result) {
            resultTextView.setText(result);
        }
    }
}