Android Cordova 插件锁定 UI 线程，即使使用了线程池

Question

我写了一个 Cordova 插件，可以在 Android 上调整图像大小，但是 UI 在翻动大量图像（超过 100 张）时锁定，直到翻动停止.我正在对 theadPool 执行所有大小调整，最初只有一个可运行的，但在 Cordova Plugins and Thread Blocking 上阅读这篇博客 post 后，我切换到外部 class 来完成这项工作。但是我仍然得到：

W/PluginManager﹕ THREAD WARNING: exec() call to ImageStore.getImage blocked the main thread for 91ms. Plugin should use CordovaInterface.getThreadPool().

对于每个调整大小的图像，调用如下所示：

private boolean getImage(final JSONArray args, final CallbackContext callbackContext) throws JSONException {

    JSONObject argObject = args.getJSONObject(0);

    int photoId = argObject.getInt("photoId");
    final PhotoData photoData = mPhotos.get(photoId);

    cordova.getThreadPool().execute(new GetImageRunnable(photoData, callbackContext));

    return true;
}

除了传入的 photoData 对象，GetImageRunnable 没有指向主插件的链接。有什么方法可以查看是什么导致了速度变慢或阻塞了主线程？

Answer 1

你可以试试下面的代码，它使用最小的 AsyncTask 到运行 GetImageRunnable:

private boolean getImage(final JSONArray args, final CallbackContext callbackContext) throws JSONException {

    JSONObject argObject = args.getJSONObject(0);

    int photoId = argObject.getInt("photoId");
    final PhotoData photoData = mPhotos.get(photoId);

    (new MyTask(photoData, callbackContext)).execute();

    return true;
}

private class MyTask extends AsyncTask<Void, Void, Void> {

    private PhotoData mPhotoData;
    private CallbackContext mCallbackContext;

    public MyTask(PhotoData photoData, CallbackContext callbackContext) {
        mPhotoData = photoData
        mCallbackContext = callbackContext;
    }

    protected Void doInBackground(Void... v) {
        (new GetImageRunnable(photoData, callbackContext)).run();
        return null;
    }

    protected void onProgressUpdate(Void... v) {
    }

    protected void onPostExecute(Void v) {
    }
}

虽然还有一些不足之处；回调将在后台线程中为运行。如果你需要在主线程中是运行，你可以屏蔽初始的CallbackContext（它不是最终的），并将结果传递给onPostExecute中的原始结果：

private boolean getImage(final JSONArray args, final CallbackContext callbackContext) throws JSONException {

    JSONObject argObject = args.getJSONObject(0);

    int photoId = argObject.getInt("photoId");
    final PhotoData photoData = mPhotos.get(photoId);

    (new MyTask(photoData, callbackContext)).execute();

    return true;
}

private class MyTask extends AsyncTask<Void, Void, Void> {

    private PhotoData mPhotoData;
    private CallbackContext mCallbackContext;
    private CallbackContext mMaskedContext;

    public MyTask(PhotoData photoData, CallbackContext callbackContext) {
        mPhotoData = photoData
        mCallbackContext = callbackContext;
        mMaskedContext = new MyCallbackContext(callbackContext);
    }

    protected Void doInBackground(Void... v) {
        (new GetImageRunnable(photoData, mMaskedContext)).run();
        return null;
    }

    protected void onProgressUpdate(Void... v) {
    }

    protected void onPostExecute(Void v) {
        mCallbackContext.sendPluginResult(mMaskedContext.getPluginResult());
    }
}

class MyCallbackContext extends CallbackContext {
    private CallbackContext mOriginalContext;
    private PluginResult mPluginResult;

    public MyCallbackContext(CallbackContext originalContext) {
        super(originalContext.getCallbackId(), null);
        mOriginalContext = originalContext;
    }

    public void sendPluginResult(PluginResult pluginResult) {
        mPluginResult = pluginResult;
    }

    public pluginResult getPluginResult() {
        return mPluginResult;
    }
}

注意：这没有经过测试，代码只是为了说明思路。

Android Cordova 插件锁定 UI 线程，即使使用了线程池

Android Cordova Plugin locks UI thread even though Thread Pool is used

android

phonegap-plugins

cordova