Android Service 生命周期管理与数据传递：避免重复启动与多线程问题

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private double currentX1 = 10.0;
    private double currentY1 = 20.0;
    private double currentRadius = 5.0;
    private int currentK = 1;

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

        Button startServiceButton = findViewById(R.id.startServiceButton);
        startServiceButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 模拟数据更新
                currentX1 += 0.5;
                currentY1 += 0.2;
                currentK += 1;

                // 启动或更新Service，并通过Intent传递最新数据
                startMyService();
            }
        });
    }

    private void startMyService() {
        Intent serviceIntent = new Intent(this, ForegroundService.class);
        serviceIntent.putExtra("EXTRA_X1", currentX1);
        serviceIntent.putExtra("EXTRA_Y1", currentY1);
        serviceIntent.putExtra("EXTRA_RADIUS", currentRadius);
        serviceIntent.putExtra("EXTRA_K", currentK);
        startService(serviceIntent);
    }
}

import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.util.Log;
import androidx.annotation.Nullable;

public class ForegroundService extends Service {

    // 成员变量，用于存储Service当前处理的数据
    private double currentX1;
    private double currentY1;
    private double currentRadius;
    private int currentK;

    // 用于调度后台任务的Handler
    private Handler handler;
    // 后台任务的Runnable实例
    private Runnable serviceTask;

    @Override
    public void onCreate() {
        super.onCreate();
        // 初始化Handler，使其与主线程的Looper关联
        // 如果需要任务在独立后台线程运行，应使用HandlerThread
        handler = new Handler(Looper.getMainLooper());

        // 定义后台任务
        serviceTask = new Runnable() {
            @Override
            public void run() {
                // 使用Service内部的最新数据进行操作
                Log.e("ForegroundService", "Running with X1: " + currentX1 + ", Y1: " + currentY1 + ", K: " + currentK);
                // 任务执行完毕后，再次调度自身，实现循环
                handler.postDelayed(this, 1000); // 每秒执行一次
            }
        };
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // 从Intent中获取最新数据
        if (intent != null) {
            currentX1 = intent.getDoubleExtra("EXTRA_X1", 0.0);
            currentY1 = intent.getDoubleExtra("EXTRA_Y1", 0.0);
            currentRadius = intent.getDoubleExtra("EXTRA_RADIUS", 0.0);
            currentK = intent.getIntExtra("EXTRA_K", 0);
        }

        // 关键步骤：在启动新任务之前，移除所有待处理的相同任务
        // 这确保了无论onStartCommand被调用多少次，都只有一个serviceTask在运行
        handler.removeCallbacks(serviceTask);
        // 启动（或重新启动）任务
        handler.post(serviceTask);

        // 返回START_STICKY表示如果Service被系统杀死，系统会尝试重新创建它并调用onStartCommand
        return START_STICKY;
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        // Service销毁时，移除所有待处理的任务，防止内存泄漏和不必要的后台操作
        handler.removeCallbacks(serviceTask);
        Log.e("ForegroundService", "Service destroyed. Background task stopped.");
    }
}