宁静的API服务

Question

宁静的API服务

Mar*_*tyn 220 api rest android web-services

我正在寻找一个可以用来调用基于Web的REST API的服务.

基本上我想在app init上启动服务然后我希望能够要求该服务请求URL并返回结果.与此同时,我希望能够显示进度窗口或类似的东西.

我已经创建了一个目前使用IDL的服务,我已经阅读过你只需要这个用于跨应用程序通信的地方,所以请考虑这些需求,但不确定如何在没有它的情况下进行回调.此外,当我点击post(Config.getURL("login"), values)应用程序似乎暂停一段时间(似乎很奇怪 - 认为服务背后的想法是它运行在不同的线程!)

目前我有一个带post的服务,里面有http方法,一些AIDL文件(用于双向通信),一个ServiceManager,它处理启动,停止,绑定等服务,我正在动态创建一个具有特定代码的Handler根据需要进行回调.

我不希望任何人给我一个完整的代码库来工作,但一些指针将不胜感激.

代码(大部分)已满:

public class RestfulAPIService extends Service  {

final RemoteCallbackList<IRemoteServiceCallback> mCallbacks = new RemoteCallbackList<IRemoteServiceCallback>();

public void onStart(Intent intent, int startId) {
    super.onStart(intent, startId);
}
public IBinder onBind(Intent intent) {
    return binder;
}
public void onCreate() {
    super.onCreate();
}
public void onDestroy() {
    super.onDestroy();
    mCallbacks.kill();
}
private final IRestfulService.Stub binder = new IRestfulService.Stub() {
    public void doLogin(String username, String password) {

        Message msg = new Message();
        Bundle data = new Bundle();
        HashMap<String, String> values = new HashMap<String, String>();
        values.put("username", username);
        values.put("password", password);
        String result = post(Config.getURL("login"), values);
        data.putString("response", result);
        msg.setData(data);
        msg.what = Config.ACTION_LOGIN;
        mHandler.sendMessage(msg);
    }

    public void registerCallback(IRemoteServiceCallback cb) {
        if (cb != null)
            mCallbacks.register(cb);
    }
};

private final Handler mHandler = new Handler() {
    public void handleMessage(Message msg) {

        // Broadcast to all clients the new value.
        final int N = mCallbacks.beginBroadcast();
        for (int i = 0; i < N; i++) {
            try {
                switch (msg.what) {
                case Config.ACTION_LOGIN:
                    mCallbacks.getBroadcastItem(i).userLogIn( msg.getData().getString("response"));
                    break;
                default:
                    super.handleMessage(msg);
                    return;

                }
            } catch (RemoteException e) {
            }
        }
        mCallbacks.finishBroadcast();
    }
    public String post(String url, HashMap<String, String> namePairs) {...}
    public String get(String url) {...}
};

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一些AIDL文件:

package com.something.android

oneway interface IRemoteServiceCallback {
    void userLogIn(String result);
}

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和

package com.something.android
import com.something.android.IRemoteServiceCallback;

interface IRestfulService {
    void doLogin(in String username, in String password);
    void registerCallback(IRemoteServiceCallback cb);
}

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和服务经理:

public class ServiceManager {

    final RemoteCallbackList<IRemoteServiceCallback> mCallbacks = new RemoteCallbackList<IRemoteServiceCallback>();
    public IRestfulService restfulService;
    private RestfulServiceConnection conn;
    private boolean started = false;
    private Context context;

    public ServiceManager(Context context) {
        this.context = context;
    }

    public void startService() {
        if (started) {
            Toast.makeText(context, "Service already started", Toast.LENGTH_SHORT).show();
        } else {
            Intent i = new Intent();
            i.setClassName("com.something.android", "com.something.android.RestfulAPIService");
            context.startService(i);
            started = true;
        }
    }

    public void stopService() {
        if (!started) {
            Toast.makeText(context, "Service not yet started", Toast.LENGTH_SHORT).show();
        } else {
            Intent i = new Intent();
            i.setClassName("com.something.android", "com.something.android.RestfulAPIService");
            context.stopService(i);
            started = false;
        }
    }

    public void bindService() {
        if (conn == null) {
            conn = new RestfulServiceConnection();
            Intent i = new Intent();
            i.setClassName("com.something.android", "com.something.android.RestfulAPIService");
            context.bindService(i, conn, Context.BIND_AUTO_CREATE);
        } else {
            Toast.makeText(context, "Cannot bind - service already bound", Toast.LENGTH_SHORT).show();
        }
    }

    protected void destroy() {
        releaseService();
    }

    private void releaseService() {
        if (conn != null) {
            context.unbindService(conn);
            conn = null;
            Log.d(LOG_TAG, "unbindService()");
        } else {
            Toast.makeText(context, "Cannot unbind - service not bound", Toast.LENGTH_SHORT).show();
        }
    }

    class RestfulServiceConnection implements ServiceConnection {
        public void onServiceConnected(ComponentName className, IBinder boundService) {
            restfulService = IRestfulService.Stub.asInterface((IBinder) boundService);
            try {
            restfulService.registerCallback(mCallback);
            } catch (RemoteException e) {}
        }

        public void onServiceDisconnected(ComponentName className) {
            restfulService = null;
        }
    };

    private IRemoteServiceCallback mCallback = new IRemoteServiceCallback.Stub() {
        public void userLogIn(String result) throws RemoteException {
            mHandler.sendMessage(mHandler.obtainMessage(Config.ACTION_LOGIN, result));

        }
    };

    private Handler mHandler;

    public void setHandler(Handler handler) {
        mHandler = handler;
    }
}

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服务初始化和绑定:

// this I'm calling on app onCreate
servicemanager = new ServiceManager(this);
servicemanager.startService();
servicemanager.bindService();
application = (ApplicationState)this.getApplication();
application.setServiceManager(servicemanager);

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服务功能调用:

// this lot i'm calling as required - in this example for login
progressDialog = new ProgressDialog(Login.this);
progressDialog.setMessage("Logging you in...");
progressDialog.show();

application = (ApplicationState) getApplication();
servicemanager = application.getServiceManager();
servicemanager.setHandler(mHandler);

try {
    servicemanager.restfulService.doLogin(args[0], args[1]);
} catch (RemoteException e) {
    e.printStackTrace();
}

...later in the same file...

Handler mHandler = new Handler() {
    public void handleMessage(Message msg) {

        switch (msg.what) {
        case Config.ACTION_LOGIN:

            if (progressDialog.isShowing()) {
                progressDialog.dismiss();
            }

            try {
                ...process login results...
                }
            } catch (JSONException e) {
                Log.e("JSON", "There was an error parsing the JSON", e);
            }
            break;
        default:
            super.handleMessage(msg);
        }

    }

};

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Answer 1

Rob*_*ond 282

如果您的服务将成为您应用程序的一部分,那么您将使它变得比它需要的更复杂.由于您有一个从RESTful Web服务获取某些数据的简单用例,因此您应该查看ResultReceiver和IntentService.

当您要执行某些操作时,此Service + ResultReceiver模式通过使用startService()启动或绑定到服务来工作.您可以指定要执行的操作,并通过Intent中的extras传入ResultReceiver(活动).

在服务中,您实现onHandleIntent以执行Intent中指定的操作.操作完成后,使用传入的ResultReceiver 将消息发送回Activity,此时将调用onReceiveResult.

例如,您希望从Web Service中提取一些数据.

您创建意图并调用startService.
服务中的操作开始,它向活动发送一条消息,说明它已启动
活动处理消息并显示进度.
该服务完成操作并将一些数据发送回您的活动.
您的活动处理数据并将其放入列表视图中
该服务会向您发送一条消息,说明已完成,并且它会自行终止.
活动获取完成消息并隐藏进度对话框.

我知道您提到过您不想使用代码库,但开源Google I/O 2010应用程序以我正在描述的方式使用服务.

更新以添加示例代码:

活动.

public class HomeActivity extends Activity implements MyResultReceiver.Receiver {

    public MyResultReceiver mReceiver;

    public void onCreate(Bundle savedInstanceState) {
        mReceiver = new MyResultReceiver(new Handler());
        mReceiver.setReceiver(this);
        ...
        final Intent intent = new Intent(Intent.ACTION_SYNC, null, this, QueryService.class);
        intent.putExtra("receiver", mReceiver);
        intent.putExtra("command", "query");
        startService(intent);
    }

    public void onPause() {
        mReceiver.setReceiver(null); // clear receiver so no leaks.
    }

    public void onReceiveResult(int resultCode, Bundle resultData) {
        switch (resultCode) {
        case RUNNING:
            //show progress
            break;
        case FINISHED:
            List results = resultData.getParcelableList("results");
            // do something interesting
            // hide progress
            break;
        case ERROR:
            // handle the error;
            break;
    }
}

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服务:

public class QueryService extends IntentService {
    protected void onHandleIntent(Intent intent) {
        final ResultReceiver receiver = intent.getParcelableExtra("receiver");
        String command = intent.getStringExtra("command");
        Bundle b = new Bundle();
        if(command.equals("query") {
            receiver.send(STATUS_RUNNING, Bundle.EMPTY);
            try {
                // get some data or something           
                b.putParcelableArrayList("results", results);
                receiver.send(STATUS_FINISHED, b)
            } catch(Exception e) {
                b.putString(Intent.EXTRA_TEXT, e.toString());
                receiver.send(STATUS_ERROR, b);
            }    
        }
    }
}

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ResultReceiver扩展 - 编辑即将实现MyResultReceiver.Receiver

public class MyResultReceiver implements ResultReceiver {
    private Receiver mReceiver;

    public MyResultReceiver(Handler handler) {
        super(handler);
    }

    public void setReceiver(Receiver receiver) {
        mReceiver = receiver;
    }

    public interface Receiver {
        public void onReceiveResult(int resultCode, Bundle resultData);
    }

    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
        if (mReceiver != null) {
            mReceiver.onReceiveResult(resultCode, resultData);
        }
    }
}

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答案的一小部分:当你执行mReceiver.setReceiver(null); 在onPause方法中,你应该做mReceiver.setReceiver(this); 在onResume方法中.否则,如果您的活动在未重新创建的情况下恢复,则可能无法收到活动 (29认同)
不要文档说你不必调用stopSelf,因为IntentService会为你做这件事吗？ (7认同)
@MikaelOhlson正确,如果你继承了`IntentService`,你应该_not_调用`stopSelf`,因为如果你这样做,你将失去对同一个`IntentService`的任何待处理请求. (2认同)