我正在寻找可以用来调用基于 Web 的 REST API 的服务。
基本上我想在应用程序初始化上启动一项服务,然后我希望能够要求该服务请求一个 url 并返回结果。与此同时,我希望能够显示一个进度窗口或类似的东西。
我已经创建了一个当前使用 IDL 的服务,我在某处读到你只需要它来进行跨应用程序通信,所以认为这些需要剥离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)应用程序时似乎暂停了一段时间(似乎很奇怪 - 认为服务背后的想法是它在不同的线程上运行!)
post(Config.getURL("login"), values)
目前我有一个带有 post 和 get http 方法的服务,几个 AIDL 文件(用于双向通信),一个 ServiceManager 处理启动、停止、绑定等服务,我正在动态创建一个带有特定代码的处理程序根据需要进行回调。
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。
(大部分)完整的代码:
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) {...} };
几个 AIDL 文件:
package com.something.android oneway interface IRemoteServiceCallback { void userLogIn(String result); }
和
package com.something.android import com.something.android.IRemoteServiceCallback; interface IRestfulService { void doLogin(in String username, in String password); void registerCallback(IRemoteServiceCallback cb); }
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; } }
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);
服务函数调用:
// 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); } } };
如果您的服务将成为您应用程序的一部分,那么您将使其变得比需要的复杂得多。由于您有一个从 RESTful Web 服务获取数据的简单用例,因此您应该研究ResultReceiver和IntentService。
当您想要执行某些操作时,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 传入您的 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,您使用传入的 ResultReceiver将消息发送回 Activity,此时将调用onReceiveResult 。
例如,您想从 Web 服务中提取一些数据。
我知道您提到您不想要代码库,但开源Google I/O 2010应用程序以我所描述的这种方式使用服务。
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; } }
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); } } } }
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); } } }