每次在服务中更改数据时如何更新活动

Question

我正在编写我的第一个 Android 应用，它应该计算步数（通过加速度计，源代码来自 http://www.gadgetsaint.com/android/create-pedometer-step-counter-android/）

那么我现在有什么：

1. 带有三个 TextView 字段（步数、奖金、速度）的 MainActivity。
2. 检测步数并计算距离、奖金和 速度。

此服务是绑定服务，它由三个类组成：MyService、MyServiceBinder 和 MyServiceConnection。我已经按照 Xamarin.Android 文档和示例中的说明完成了它：https://github.com/xamarin/monodroid-samples/tree/master/ApplicationFundamentals/ServiceSamples/BoundServiceDemo。

关键是每次我有一个步骤时，我都想在 MainActivity 上实时显示（更新那些文本视图）。而且我不明白如何以适当的方式做到这一点。事件？广播接收器？我对绑定/连接感到困惑，这对我来说是新事物。 请帮我让它工作！任何示例（Java 都可以）都会很有帮助。

这里是源代码（我已经从额外的代码中清理了它）。

MainActivity.cs

public class MainActivity : Activity
{
    //BOUND SERVICE: STEPSERVICE 
    MyServiceConnection myServiceConnection;

    //UI
    internal TextView textBonus, textSteps, textSpeed;

    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.Main);

        textBonus = FindViewById<TextView>(Resource.Id.textViewBonus);
        textStep = FindViewById<TextView>(Resource.Id.textViewDistance);
        textSpeed = FindViewById<TextView>(Resource.Id.textViewSpeed);
    }

    protected override void OnStart()
    {
        base.OnStart();
        if (myServiceConnection == null)
        {
            myServiceConnection = new MyServiceConnection(this);
        }
        DoBindMyService();
    }

    private void DoBindMyService()
    {
        Intent serviceIntent = new Intent(this, typeof(MyService));
        BindService(serviceIntent, myServiceConnection, Bind.AutoCreate);
    }


    protected override void OnDestroy()
    {
        //stop services!
        base.OnDestroy();
    }

    private void UpdateUI()
    {
        RunOnUiThread(() =>
        {
            textBonus.Text = myServiceConnection.Binder.Service.Bonus;              
            textSteps.Text = myServiceConnection.Binder.Service.Steps;
            textSpeed.Text = myServiceConnection.Binder.Service.Speed;
        });
    }
}

MyService.cs

[Service]
public class MyService : Service, IStepListener, ISensorEventListener
{
    //counters
    private int bonus;
    public int Bonus
    {
        get { return bonus; }
        set { bonus = value; }
    }

    private int steps = 0;
    public int StepsT
    {
        get { return steps; }
        set
        {
            steps = value;
        }
    }

    private float speed = 0.0F;
    public float Speed
    {
        get { return speed; }
        set
        {
            speed = value;
        }
    }

    public IBinder Binder { get; private set; }

    public override IBinder OnBind(Intent intent)
    {
        this.Binder = new MyServiceBinder(this);
        return this.Binder;
    }

    public override void OnCreate()
    {
        base.OnCreate();
    }

    public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
    {
        return StartCommandResult.Sticky;
    }

    public void Step(long timeNs)
    {
        Steps++;
        Bonus++;
        Speed++;
    }

    public void OnAccuracyChanged(Sensor sensor, SensorStatus accuracy)
    {
        // We don't want to do anything here.
    }

    public void OnSensorChanged(SensorEvent e)
    {
        simpleStepDetector.UpdateAccel(e.Timestamp, e.Values[0], e.Values[1], e.Values[2]);
    }
}

MyServiceConnection.cs

public class MyServiceConnection : Java.Lang.Object, IServiceConnection
{
    MainActivity mainActivity;

    public MyServiceConnection(MainActivity activity)
    {
        IsConnected = false;
        Binder = null;
        mainActivity = activity;
    }

    public bool IsConnected { get; private set; }
    public MyServiceBinder Binder { get; private set; }

    public void OnServiceConnected(ComponentName name, IBinder service)
    {
        Binder = service as MyServiceBinder;
        IsConnected = this.Binder != null;

        string message = "onSecondServiceConnected - ";

        if (IsConnected)
        {
            message = message + " bound to service " + name.ClassName;
        }
        else
        {
            message = message + " not bound to service " + name.ClassName;
        }

        mainActivity.textSpeed.Text = message;
    }

    public void OnServiceDisconnected(ComponentName name)
    {
        IsConnected = false;
        Binder = null;
    }
}

MyServiceBinder.cs

public class MyServiceBinder : Binder
{
    public MyServiceBinder(MyService service)
    {
        this.Service = service;
    }

    public MyService Service { get; private set; }
}

附言。这是我在这里的第一个问题。如果我做错了什么，请见谅。

Answer 1

有三种方法可以完成。

• 广播
• 接口
• 绑定服务

---

绑定服务

• 在您的MyServiceConnection 中添加：

  public MyService myService;
  

  并在您的 OnServiceConnected 方法中将其添加到 Binder = service as MyServiceBinder; 下：

  myService=Binder.Service;
  myService.SetActivity(mainActivity);
  

• 在你的MyService 类中添加这个（这样你就可以在你的服务中获得MainActivity 实例）：

  MainActivity mainActivity;
  public void SetActivity(MainActivity activity) {
  this.mainActivity = activity;
  }
  

  并在您的Step(long timeNs) 方法中添加mainActivity.UpdateUI();，这样您就可以更新您的UI。

• 在您的MainActivity 中，将private void UpdateUI() 替换为public void UpdateUI()。

---

界面

• 添加IUpdate接口

  public interface IUpdate
  {
      void Update();
  }
  

• 在您的MyService 中添加：

  IUpdate update;
  public void SetIUpdate(IUpdate update) {
      this.update = update;
  }
  

  并在您的 Step(long timeNs) 方法中添加 this.update.Update();。

• 在您的MyServiceConnection 类中实现IUpdate 接口，所以它会是这样的：

  public class MyServiceConnection : Java.Lang.Object, IServiceConnection,IUpdate
  {
       MainActivity mainAtivity;
  
      public MyServiceConnection(MainActivity activity)
  {
      IsConnected = false;
      Binder = null;
      mainActivity = activity;
  }
  
  public bool IsConnected { get; private set; }
  public MyServiceBinder Binder { get; private set; }
  public MyService myService;
  
  public void OnServiceConnected(ComponentName name, IBinder service)
  {
      Binder = service as MyServiceBinder;
      myService=Binder.Service;
      myService.SetIUpdate(this);
      //myService.SetActivity(mainActivity);
      IsConnected = this.Binder != null;
  
      string message = "onSecondServiceConnected - ";
  
      if (IsConnected)
      {
          message = message + " bound to service " + name.ClassName;
      }
      else
      {
          message = message + " not bound to service " + name.ClassName;
      }
  
      mainActivity.textSpeed.Text = message;
  }
  
  public void OnServiceDisconnected(ComponentName name)
  {
      IsConnected = false;
      Binder = null;
  }
  
  public void Update()
  {
      mainActivity.UpdateUI();
  }
  }
  

---

广播

这是你已经知道的。