调用 getFriends 时引发异常

Question

我得到这个异常，"无法在未调用Looper.prepare（）的线程中创建处理程序"，当我调用get或getFriends时抛出。这是我用于getFriends的代码。它是从主线程调用的。

public void returnFriendIDs(final int pointer){
    Properties properties = new Properties.Builder()
                .add(Profile.Properties.ID)
                .add(Profile.Properties.FIRST_NAME)
                .add(Profile.Properties.LAST_NAME)
                .add(Profile.Properties.INSTALLED)
                .build();
    try{
        mSimpleFacebook.getFriends(properties,  new OnFriendsListener() {
            @Override
            public void onComplete(List<Profile> friends) {
                String resultStr = "";
                Log.d(LOGPREFIX, "Number of friends = " + friends.size());
                for(Profile p : friends){
                    resultStr += p.getId()+',';
                }
                if(friends.size() > 0) returnFriends(pointer, resultStr.substring(0,resultStr.length()-1));
                else returnFriends(pointer, "");
            }
            @Override
            public void onFail(String reason){
                returnFriends(pointer, "");
            }
            @Override
            public void onException(Throwable throwable){
                Log.w(LOGPREFIX, throwable.getMessage());
                returnFriends(pointer, "");
            }
        });
    }
    catch(Throwable throwable){
        Log.w(LOGPREFIX, "In getFriends"+throwable.getMessage());
    }
}

在调用getFriends之前，我尝试过调用Looper.prepare（），但这只会导致没有调用任何回调。

我的活动结果函数是

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        //Log.w(LOGPREFIX, "onActivityResult() called.");
        mSimpleFacebook.onActivityResult(this, requestCode, resultCode, data);
        // Handle InApp Purchase call results
        if(REQUEST_INAPP_PURCHASE == requestCode)
        {
             if (!mBillingHelper.handleActivityResult(requestCode, resultCode, data)) {
                 super.onActivityResult(requestCode, resultCode, data);
             }
        }
    }

堆栈跟踪为：

Pending exception java.lang.RuntimeException thrown by 'unknown throw location'
java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
  at void android.os.Handler.<init>(android.os.Handler$Callback, boolean) (Handler.java:200)
  at void android.os.Handler.<init>() (Handler.java:114)
  at void com.facebook.RequestAsyncTask.onPreExecute() (RequestAsyncTask.java:146)
  at android.os.AsyncTask android.os.AsyncTask.executeOnExecutor(java.util.concurrent.Executor, java.lang.Object[]) (AsyncTask.java:587)
  at android.os.AsyncTask android.os.AsyncTask.execute(java.lang.Object[]) (AsyncTask.java:535)
  at void com.sromku.simple.fb.actions.GetAction.runRequest(com.facebook.Request) (GetAction.java:143)
  at void com.sromku.simple.fb.actions.GetAction.executeImpl() (GetAction.java:81)
  at void com.sromku.simple.fb.actions.AbstractAction.execute() (AbstractAction.java:17)
  at void com.sromku.simple.fb.SimpleFacebook.getFriends(com.sromku.simple.fb.entities.Profile$Properties, com.sromku.simple.fb.listeners.OnFriendsListener) (SimpleFacebook.java:594)
  at void com.fillmyblank.app.FillMyBlank.returnFriendIDs(int) (FillMyBlank.java:325)
  at void org.libsdl.app.SDLActivity.nativeInit() (SDLActivity.java:-2)
  at void org.libsdl.app.SDLMain.run() (SDLActivity.java:509)
  at void java.lang.Thread.run() (Thread.java:818)

它是用我的主函数（我相信是 UI 线程）的这段代码调用的。我使用 ndk，所以主函数是指实际的函数主函数。

    aEnv = (JNIEnv *)SDL_AndroidGetJNIEnv();
    aActivityClass = aEnv->FindClass(mClassPath.c_str());
    aStaticMid = aEnv->GetStaticMethodID(aActivityClass, "GetActivity", "()Lcom/fillmyblank/app/FillMyBlank;");
    aActivity =  aEnv->CallStaticObjectMethod(aActivityClass, aStaticMid);
    friends* fp = new friends;
    fp->waiting = SDL_CreateCond();
    aJavaMethodID = aEnv->GetMethodID(aActivityClass, "returnFriendIDs", "(I)V");
    aEnv->CallVoidMethod(aActivity, aJavaMethodID, fp);

编辑：添加了堆栈跟踪

编辑：添加了调用函数。

Answer 1

解释

异常被抛出在AsyncTask的onPreExecute部分，该部分是Facebook库（com.facebook.RequestAsyncTask）的一部分。

onPreExecute在与 AsyncTask 的调用方相同的线程中执行。如果调用方是 ui 线程，没问题，它会工作。如果调用方不是 ui 线程，它可能会失败（很有可能）。如果使用 UI 的任何组件或与 UI 相关的任何组件，它将失败。

在您的情况下，它不是在 ui 线程中执行，而是在没有消息循环的常规线程中执行，因此抛出这个著名的异常： Can't create handler inside thread that has not called Looper.prepare()

解决方案

您必须使用 runOnUiThread 方法，该方法将确保您的代码在 ui 线程中执行。 runOnUiThread将Runnable作为参数。

public void returnFriendIDs(final int pointer)
{
    runOnUiThread(new Runnable()
    {
        @Override
        public void run()
        {
            Properties properties = new Properties.Builder()
            .add(Profile.Properties.ID)
            .add(Profile.Properties.FIRST_NAME)
            .add(Profile.Properties.LAST_NAME)
            .add(Profile.Properties.INSTALLED)
            .build();
            try{
                mSimpleFacebook.getFriends(properties,  new OnFriendsListener() {
                    @Override
                    public void onComplete(List<Profile> friends) {
                        String resultStr = "";
                        Log.d(LOGPREFIX, "Number of friends = " + friends.size());
                        for(Profile p : friends){
                            resultStr += p.getId()+',';
                        }
                        if(friends.size() > 0) returnFriends(pointer, resultStr.substring(0,resultStr.length()-1));
                        else returnFriends(pointer, "");
                    }
                    @Override
                    public void onFail(String reason){
                        returnFriends(pointer, "");
                    }
                    @Override
                    public void onException(Throwable throwable){
                        Log.w(LOGPREFIX, throwable.getMessage());
                        returnFriends(pointer, "");
                    }
                });
            }
            catch(Throwable throwable){
                Log.w(LOGPREFIX, "In getFriends"+throwable.getMessage());
            }
        }
    });
}