java - "SyncAdapter"执行过程中出现异常

Question

我在实现具有虚拟帐户和虚拟帐户身份 validator 的 Syncadapter 时遇到问题。

我的帐户 validator ，CNAuthenticator:

public class CNAuthenticator extends AbstractAccountAuthenticator {

public CNAuthenticator(Context context) {
    super(context);
}

@Override
public Bundle editProperties(AccountAuthenticatorResponse response, String accountType) {
    return null;
}

@Override
public Bundle addAccount(AccountAuthenticatorResponse response, String accountType, String authTokenType, String[] requiredFeatures, Bundle options) throws NetworkErrorException {
    return null;
}

@Override
public Bundle confirmCredentials(AccountAuthenticatorResponse response, Account account, Bundle options) throws NetworkErrorException {
    return null;
}

@Override
public Bundle getAuthToken(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options) throws NetworkErrorException {
    return null;
}

@Override
public String getAuthTokenLabel(String authTokenType) {
    return null;
}

@Override
public Bundle updateCredentials(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options) throws NetworkErrorException {
    return null;
}

@Override
public Bundle hasFeatures(AccountAuthenticatorResponse response, Account account, String[] features) throws NetworkErrorException {
    return null;
}
}

我的身份验证服务 CNAuthenticatorService:

public class CNAuthenticatorService extends Service {
private CNAuthenticator cnAuthenticator;
public CNAuthenticatorService() {
}

@Override
public void onCreate() {
    super.onCreate();
    cnAuthenticator= new CNAuthenticator(this);
}

@Override
public IBinder onBind(Intent intent) {
    // TODO: Return the communication channel to the service.
    return cnAuthenticator.getIBinder();
}
}

我的同步适配器，CNSyncAdapter:

public class CNSyncAdapter extends AbstractThreadedSyncAdapter {
private static final String LOG_TAG = "CNSyncAdapter";

public CNSyncAdapter(Context context, boolean autoInitialize) {
    super(context, autoInitialize);
}

@Override
public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient provider, SyncResult syncResult) {
    Log.d(LOG_TAG, "onPerformSync Called.");
}

public static Account getSyncAccount(Context context) {
    // Get an instance of the Android account manager
    AccountManager accountManager =(AccountManager) context.getSystemService(Context.ACCOUNT_SERVICE);

    // Create the account type and default account
    Account newAccount = new Account(context.getString(R.string.app_name), context.getString(R.string.sync_account_type));

    // If the password doesn't exist, the account doesn't exist
    if ( null == accountManager.getPassword(newAccount) ) {

    /*
     * Add the account and account type, no password or user data
     * If successful, return the Account object, otherwise report an error.
     */
        if (!accountManager.addAccountExplicitly(newAccount, null, null)) {
            return null;
        }
        /*
         * If you don't set android:syncable="true" in
         * in your <provider> element in the manifest,
         * then call ContentResolver.setIsSyncable(account, AUTHORITY, 1)
         * here.
         */

    }
    return newAccount;


}


public static void syncImmediately(Context context) {
    Bundle bundle = new Bundle();
    bundle.putBoolean(ContentResolver.SYNC_EXTRAS_EXPEDITED, true);
    bundle.putBoolean(ContentResolver.SYNC_EXTRAS_MANUAL, true);
    ContentResolver.requestSync(getSyncAccount(context),
            context.getString(R.string.content_authority), bundle);
}

public static void initializeSyncAdapter(Context context) {
    getSyncAccount(context);
}


}

我的同步适配器服务，CNSyncService:

public class CNSyncService extends Service {
private static final Object sSyncAdapterLock = new Object();
private static final String LOG_TAG ="CNSyncService" ;
private static CNSyncAdapter cnSyncAdapter = null;

public CNSyncService() {
    Log.d(LOG_TAG, "onCreate");
    synchronized (sSyncAdapterLock) {
        if (cnSyncAdapter==null)
            cnSyncAdapter = new CNSyncAdapter(getBaseContext(),true);
    }
}


@Override
public IBinder onBind(Intent intent) {
    // TODO: Return the communication channel to the service.
    return cnSyncAdapter.getSyncAdapterBinder();
}
}

当我在一个 fragment 中调用 CNSyncAdapter.syncImmediately(getActivity()) 时出现异常。

我的日志猫，

06-22 19:48:35.080  27790-28417/com.mobileapplicationsclub.cashnote.app W/dalvikvm﹕ threadid=17: thread exiting with uncaught exception (group=0x41e0c2b8)
06-22 19:48:35.120  27790-28417/com.mobileapplicationsclub.cashnote.app E/AndroidRuntime﹕ FATAL EXCEPTION: SyncAdapterThread-1
java.lang.NullPointerException
        at android.content.AbstractThreadedSyncAdapter$SyncThread.run(AbstractThreadedSyncAdapter.java:252)

请帮忙。我不知道是什么原因造成的。

这很奇怪，但是当我从 getBaseContext() 更改为 getApplicationContext() 时，我收到了不同的错误。

更改后我的 logcat:

06-22 20:21:00.630  29104-29104/com.mobileapplicationsclub.cashnote.app E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate service com.mobileapplicationsclub.cashnote.app.CNSyncService: java.lang.NullPointerException
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:2406)
        at android.app.ActivityThread.access$1700(ActivityThread.java:140)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:174)
        at android.app.ActivityThread.main(ActivityThread.java:4952)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:101)
        at com.mobileapplicationsclub.cashnote.app.CNSyncService.<init>(CNSyncService.java:17)
        at java.lang.Class.newInstanceImpl(Native Method)
        at java.lang.Class.newInstance(Class.java:1319)
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:2403)

CNSyncService.java:17 是 cnSyncAdapter = new CNSyncAdapter(getApplicationContext(),true)

Answer 1

您应该使用服务构造函数。当您调用 startService 时，Android 会隐式执行此操作。您可以使用 onCreate 回调方法来实现您的自定义代码:

public class CNSyncService extends Service {
    private static final Object sSyncAdapterLock = new Object();
    private static final String LOG_TAG ="CNSyncService" ;
    private static CNSyncAdapter cnSyncAdapter = null;

    @Override
    public void onCreate() {
        super.onCreate();

        Log.d(LOG_TAG, "onCreate");
        synchronized (sSyncAdapterLock) {
            if (cnSyncAdapter==null)
                cnSyncAdapter = new CNSyncAdapter(getBaseContext(),true);
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        return cnSyncAdapter.getSyncAdapterBinder();
    }
}