Question

我是android和java的新手，遇到过一个问题。我有一个方法活动，我想在后台使用它们。对于后台我使用了Service类。问题是我无法将活动对象传递给服务构造函数，因为它不能包含任何参数。我读了如何通过打算发送字符串和双打，但我找不到如何传递活动类。

＆＃13;

public class MainActivity extends Activity
{
    @Override
    protected void onCreate( Bundle savedInstanceState ){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public void onStop(){
        super.onStop();
        startService(new Intent(this, MyService.class));
    }

    @Override
    public void onResume(){
        super.onResume();
        stopService(new Intent(this, MyService.class));
    }

    public void toast(String msg) {
        Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
    }
}

//---------------------------------------

public class MyService extends Service
{
    private MainActivity main;

    public MyService() {
    }

    @Override
    public void onCreate() {
        super.onCreate();
        main.toast("test");    // <- here I want to use some method
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

＆＃13;

感谢您的帮助！

Answer 1

您好请参阅以下步骤确定帮助您。

第1步。定义服务用于传达事件的界面：

public interface ServiceCallbacks {
    void Showtoast(String msg);
}

第2步。编写您的服务类。您的活动将绑定到此服务。另外，我们将添加一个方法来设置ServiceCallbacks。

public class MyService extends Service {
    // Binder given to clients 
    private final IBinder binder = new LocalBinder();
    // Registered callbacks 
    private ServiceCallbacks serviceCallbacks;


    // Class used for the client Binder. 
    public class LocalBinder extends Binder {
        MyService getService() { 
            // Return this instance of MyService so clients can call public methods 
            return MyService.this;
        } 
    } 

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

    public void setCallbacks(ServiceCallbacks callbacks) {
        serviceCallbacks = callbacks;
    } 
}

第3步。按照相同的指南编写Activity类，同时使其实现ServiceCallbacks接口。从服务绑定/取消绑定时，您将通过调用服务上的setCallbacks来注册/取消注册它。

public class MyActivity extends Activity implements ServiceCallbacks {
    private MyService service;
    private boolean bound = false;

    @Override 
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ......
    } 

    @Override 
    protected void onStart() { 
        super.onStart(); 
        // bind to Service 
        Intent intent = new Intent(this, MyService.class);
        bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE);
    } 

    @Override 
    protected void onStop() { 
        super.onStop(); 
        // Unbind from service 
        if (bound) {
            service.setCallbacks(null); // unregister
            unbindService(serviceConnection);
            bound = false;
        } 
    } 

    /** Callbacks for service binding, passed to bindService() */ 
    private ServiceConnection serviceConnection = new ServiceConnection() {

        @Override 
        public void onServiceConnected(ComponentName className,
                IBinder service) {
            // cast the IBinder and get MyService instance 
            LocalBinder binder = (LocalBinder) service;
            service = binder.getService();
            bound = true;
            service.setCallbacks(this); // register
        } 

        @Override 
        public void onServiceDisconnected(ComponentName arg0) {
            bound = false;
        } 
    }; 

    /* Defined by ServiceCallbacks interface */ 
    @Override 
    public void Showtoast(String message) { 
         Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
    } 
}

如果您有任何疑问，请与我们联系。

Answer 2

为什么这么复杂？您可以轻松地从服务中展示烤面包因此，您可以将代码置于服务的onCreate方法

中

Toast.makeText(this, "text", Toast.LENGTH_SHORT).show();

将类对象传递给服务

2 个答案: