android service 构造函数,Android IntentService无法实例化类;没有空构造函数

我有一个MainActivity类，需要访问在线API(因此使用网络资源)。这需要我在单独的文件HttpRequestService.java中创建的后台线程。

MainActivity.java：

public class MainActivity extends Activity {

public static final String API_KEY = "KEYKEYKEYKEYKEY";

public static final String CLIENT_ID = "IDIDIDIDIDIDID";

private final String BROADCAST_ACTION = "com.example.BROADCAST";

private final String EXTENDED_DATA_STATUS = "com.example.STATUS";

static final String LOGCAT_TAG = "TAGTAGTAGTAGTAG";

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

}

@Override

protected void onResume() {

super.onResume();

String token = "TOKENTOKENTOKENTOKEN";

String urlString = "https://www.example.com/api?key=" + API_KEY;

// Create and start intent for HttpRequestService background thread.

Intent httpRequestServiceIntent = new Intent(this, HttpRequestService.class);

httpRequestServiceIntent.putExtra("token", token);

httpRequestServiceIntent.putExtra("urlString", urlString);

httpRequestServiceIntent.putExtra("client_id", CLIENT_ID);

DownloadStateReceiver downloadStateReceiver = new DownloadStateReceiver();

LocalBroadcastManager.getInstance(this).registerReceiver(downloadStateReceiver, new IntentFilter(BROADCAST_ACTION));

this.startService(httpRequestServiceIntent);

}

private class DownloadStateReceiver extends BroadcastReceiver {

// Broadcast receiver for receiving status updates from IntentService

private DownloadStateReceiver() {

// prevents instantiation

}

@Override

public void onReceive(Context context, Intent intent) {

String message = intent.getStringExtra(EXTENDED_DATA_STATUS);

Log.d(LOGCAT_TAG, "onReceive received message: " + message);

Toast.makeText(context, "Success!: " + message, Toast.LENGTH_LONG).show();

}

}

HttpRequestService.java：

public final class HttpRequestService extends IntentService {

public HttpRequestService(String name) {

super(name);

Log.e(LOGCAT_TAG, "You called the HttpRequestService directly. Don't do that. Call onHandleIntent.");

}

private final String LOGCAT_TAG = "HttpRequestService";

private final String BROADCAST_ACTION = "com.genda.dayplanner.BROADCAST";

private final String EXTENDED_DATA_STATUS = "com.genda.dayplanner.STATUS";

@Override

protected void onHandleIntent(Intent intent) {

// Gets data from the incoming Intent

String token = intent.getStringExtra("token");

String urlString = intent.getStringExtra("urlString");

String client_id = intent.getStringExtra("client_id");

Boolean extraError = false;

if (token == null) {

Log.e(LOGCAT_TAG, "Intent didn't contain required token.");

extraError = true;

}

if (urlString == null) {

Log.e(LOGCAT_TAG, "Intent didn't contain required urlBundle.");

extraError = true;

}

if (client_id == null) {

Log.e(LOGCAT_TAG, "Intent didn't contain required client_id.");

extraError = true;

}

if (extraError == true) {

// error response

}

// Now do request

URL url = null;

try {

url = new URL(urlString);

} catch (MalformedURLException e) {

Log.e(LOGCAT_TAG, "The URL for requesting the tasks API was malformed.");

}

HttpURLConnection conn = null;

try {

conn = (HttpURLConnection) url.openConnection();

} catch (IOException e) {

Log.e(LOGCAT_TAG, "Bad connection to the API URL");

}

conn.addRequestProperty("client_id", client_id);

conn.setRequestProperty("Authorization", "OAuth " + token);

String result = null;

try {

InputStream in = new BufferedInputStream(conn.getInputStream());

result = convertStreamToString(in);

} catch (IOException e) {

e.printStackTrace();

} finally {

conn.disconnect();

}

// Create new Intent with URI object

Intent localIntent = new Intent(BROADCAST_ACTION);

localIntent.putExtra(EXTENDED_DATA_STATUS, result);

// Broadcasts intent to receivers in this app.

LocalBroadcastManager.getInstance(this).sendBroadcast(localIntent);

}

public static String convertStreamToString(InputStream in) {

// Use BufferedReader.readLine() method. Iterate until BufferedReader returns null (no more data to read). Each line appended to StringBuilder.

BufferedReader reader = new BufferedReader(new InputStreamReader(in));

StringBuilder sb = new StringBuilder();

String line = null;

try {

while ((line = reader.readLine()) != null) {

sb.append(line + "\n");

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

in.close();

} catch (IOException e) {

e.printStackTrace();

}

}

return sb.toString();

}

}

这是LogCat：

09-21 17:15:28.157: D/dalvikvm(11055): newInstance failed: no ()

09-21 17:15:28.157: D/AndroidRuntime(11055): Shutting down VM

09-21 17:15:28.157: W/dalvikvm(11055): threadid=1: thread exiting with uncaught exception (group=0x41f3b700)

09-21 17:15:28.167: E/AndroidRuntime(11055): FATAL EXCEPTION: main

09-21 17:15:28.167: E/AndroidRuntime(11055): java.lang.RuntimeException: Unable to instantiate service com.example.HttpRequestService: java.lang.InstantiationException: can't instantiate class com.example.HttpRequestService; no empty constructor

09-21 17:15:28.167: E/AndroidRuntime(11055): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2561)

09-21 17:15:28.167: E/AndroidRuntime(11055): at android.app.ActivityThread.access$1600(ActivityThread.java:141)

09-21 17:15:28.167: E/AndroidRuntime(11055): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1338)

09-21 17:15:28.167: E/AndroidRuntime(11055): at android.os.Handler.dispatchMessage(Handler.java:99)

09-21 17:15:28.167: E/AndroidRuntime(11055): at android.os.Looper.loop(Looper.java:137)

09-21 17:15:28.167: E/AndroidRuntime(11055): at android.app.ActivityThread.main(ActivityThread.java:5103)

09-21 17:15:28.167: E/AndroidRuntime(11055): at java.lang.reflect.Method.invokeNative(Native Method)

09-21 17:15:28.167: E/AndroidRuntime(11055): at java.lang.reflect.Method.invoke(Method.java:525)

09-21 17:15:28.167: E/AndroidRuntime(11055): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)

09-21 17:15:28.167: E/AndroidRuntime(11055): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)

09-21 17:15:28.167: E/AndroidRuntime(11055): at dalvik.system.NativeStart.main(Native Method)

09-21 17:15:28.167: E/AndroidRuntime(11055): Caused by: java.lang.InstantiationException: can't instantiate class com.example.HttpRequestService; no empty constructor

09-21 17:15:28.167: E/AndroidRuntime(11055): at java.lang.Class.newInstanceImpl(Native Method)

09-21 17:15:28.167: E/AndroidRuntime(11055): at java.lang.Class.newInstance(Class.java:1130)

09-21 17:15:28.167: E/AndroidRuntime(11055): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2558)

09-21 17:15:28.167: E/AndroidRuntime(11055): ... 10 more

我认为的重要部分是无法实例化类com.example.HttpRequestService;没有空构造函数。我已经看过类似的其他几个讨论，但是他们都能够解决问题，因为他们的类是他们的MainActivity的子类。所以他们只是让这个子类静态化，解决了这个问题。不幸的是，作为一个单独的类HttpRequestService不能是静态的。有什么建议么？