studio - volley android example

¿Cómo obtener una devolución de llamada final en setImageUrl con la biblioteca Volley y NetworkImageView?

Question

Estoy probando la nueva biblioteca de Volley de Google, se ve nítida y carga imágenes rápidamente cuando uso este método setImageUrl :

holder.image.setImageUrl(url, ImageCacheManager.getInstance().getImageLoader());

Quiero agregarle un método de devolución de llamada / escucha que se activará cuando finalice la carga, para poder eliminar la vista de la barra de progressBar y mostrar la imagen. Es una opción que existe en las bibliotecas de Universal Image Loader y Picasso, pero por alguna razón, no puedo encontrar una manera de hacerlo en Volley, probé diferentes opciones de Google pero hasta ahora no he encontrado ninguna referencia.

¿Alguien tiene un ejemplo de código para ilustrar cómo se hace?

Answer 1

Lo hice de esta manera:

mImageLoader.get(url, new ImageLoader.ImageListener() {
    @Override
    public void onResponse(ImageLoader.ImageContainer response, boolean isImmediate) {
        if (response.getBitmap() != null)
            //some code
        else
            //some code
    }
    @Override
    public void onErrorResponse(VolleyError error) {
    }
});

Answer 2

Otro enfoque (similar al código de @Simulant anterior) es usar un ImageView normal en su xml y luego realizar la solicitud de imagen usando Volley.ImageRequest. Si usas el patrón Singleton recomendado por Google , se vería así:

ImageView mImageView = (ImageView) findViewById(R.id.myimageview);
RequestQueue requestQueue = MyVolleySingleton.getInstance(mContext).getRequestQueue();
ImageRequest mainImageRequest = new ImageRequest(myImageURL,
    new Response.Listener<Bitmap>() {
       @Override
       public void onResponse(Bitmap bitmap) {
          // set the image here
          mImageView.setImageBitmap(bitmap);
          // hide the spinner here
       }
    }, 0, 0, null, null);

 requestQueue.add(mainImageRequest);

Por cierto: asegúrese de utilizar un ImageView normal en lugar de NetworkImageView o la imagen no se mostrará correctamente.

Answer 3

Otro enfoque más, que se basa en conocer los aspectos internos de NetworkImageView, es hacer una subclase de NetworkImageView para observar la aplicación de mErrorImageId.

public class ManagedNetworkImageView extends NetworkImageView{
    private int mErrorResId;

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

    public ManagedNetworkImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ManagedNetworkImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    public void setErrorImageResId(int errorImage) {
        mErrorResId = errorImage;
        super.setErrorImageResId(errorImage);
    }

    @Override
    public void setImageResource(int resId) {
        if (resId == mErrorResId) {
            // TODO Handle the error here
        }
        super.setImageResource(resId);
    }

    @Override
    public void setImageBitmap(Bitmap bm) {
        // TODO Handle the success here
        super.setImageBitmap(bm);
    }
}

También deberá reemplazar NetworkImageView con ManagedNetworkImageView en sus archivos de diseño.

Es un poco intrincado, pero funciona cuando NetworkImageView ya es la solución elegida.

Answer 4

Paso 1: Declare imageLoader, (tengo una clase MySocialMediaSingleton para administrar la Solicitud de Volley)

ImageLoader imageLoader = MySocialMediaSingleton.getInstance(context).getImageLoader();

Paso 2: utilizar la devolución de llamada para imageLoader

imageLoader.get(url, new ImageLoader.ImageListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
             //an error ocurred
        }

        @Override
        public void onResponse(ImageLoader.ImageContainer response, boolean isImmediate) {
            if (response.getBitmap() != null) {
                //loadingView gone
            } else {
                //some code
            }
        }
    });

Paso 3: Muestra la respuesta en tu imageView o NetworkImageView

holder.image.setImageUrl(ImageCacheManager.getInstance().getImageLoader(), imageLoader);

Answer 5

Puede usar esta Vista en lugar de la Vista de Google (he copiado fuentes y he realizado algunos cambios):

public class VolleyImageView extends ImageView {

    public interface ResponseObserver
    {
        public void onError();
        public void onSuccess();
    }

    private ResponseObserver mObserver;

    public void setResponseObserver(ResponseObserver observer) {
        mObserver = observer;
    }

    /**
     * The URL of the network image to load
     */
    private String mUrl;

    /**
     * Resource ID of the image to be used as a placeholder until the network image is loaded.
     */
    private int mDefaultImageId;

    /**
     * Resource ID of the image to be used if the network response fails.
     */
    private int mErrorImageId;

    /**
     * Local copy of the ImageLoader.
     */
    private ImageLoader mImageLoader;

    /**
     * Current ImageContainer. (either in-flight or finished)
     */
    private ImageContainer mImageContainer;

    public VolleyImageView(Context context) {
        this(context, null);
    }

    public VolleyImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public VolleyImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    /**
     * Sets URL of the image that should be loaded into this view. Note that calling this will
     * immediately either set the cached image (if available) or the default image specified by
     * {@link VolleyImageView#setDefaultImageResId(int)} on the view.
     *
     * NOTE: If applicable, {@link VolleyImageView#setDefaultImageResId(int)} and {@link
     * VolleyImageView#setErrorImageResId(int)} should be called prior to calling this function.
     *
     * @param url         The URL that should be loaded into this ImageView.
     * @param imageLoader ImageLoader that will be used to make the request.
     */
    public void setImageUrl(String url, ImageLoader imageLoader) {
        mUrl = url;
        mImageLoader = imageLoader;
        // The URL has potentially changed. See if we need to load it.
        loadImageIfNecessary(false);
    }

    /**
     * Sets the default image resource ID to be used for this view until the attempt to load it
     * completes.
     */
    public void setDefaultImageResId(int defaultImage) {
        mDefaultImageId = defaultImage;
    }

    /**
     * Sets the error image resource ID to be used for this view in the event that the image
     * requested fails to load.
     */
    public void setErrorImageResId(int errorImage) {
        mErrorImageId = errorImage;
    }

    /**
     * Loads the image for the view if it isn''t already loaded.
     *
     * @param isInLayoutPass True if this was invoked from a layout pass, false otherwise.
     */
    private void loadImageIfNecessary(final boolean isInLayoutPass) {
        int width = getWidth();
        int height = getHeight();

        boolean isFullyWrapContent = getLayoutParams() != null
                && getLayoutParams().height == LayoutParams.WRAP_CONTENT
                && getLayoutParams().width == LayoutParams.WRAP_CONTENT;
        // if the view''s bounds aren''t known yet, and this is not a wrap-content/wrap-content
        // view, hold off on loading the image.
        if (width == 0 && height == 0 && !isFullyWrapContent) {
            return;
        }

        // if the URL to be loaded in this view is empty, cancel any old requests and clear the
        // currently loaded image.
        if (TextUtils.isEmpty(mUrl)) {
            if (mImageContainer != null) {
                mImageContainer.cancelRequest();
                mImageContainer = null;
            }
            setDefaultImageOrNull();
            return;
        }

        // if there was an old request in this view, check if it needs to be canceled.
        if (mImageContainer != null && mImageContainer.getRequestUrl() != null) {
            if (mImageContainer.getRequestUrl().equals(mUrl)) {
                // if the request is from the same URL, return.
                return;
            } else {
                // if there is a pre-existing request, cancel it if it''s fetching a different URL.
                mImageContainer.cancelRequest();
                setDefaultImageOrNull();
            }
        }

        // The pre-existing content of this view didn''t match the current URL. Load the new image
        // from the network.
        ImageContainer newContainer = mImageLoader.get(mUrl,
                new ImageListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        if (mErrorImageId != 0) {
                            setImageResource(mErrorImageId);
                        }

                        if(mObserver!=null)
                        {
                            mObserver.onError();
                        }
                    }

                    @Override
                    public void onResponse(final ImageContainer response, boolean isImmediate) {
                        // If this was an immediate response that was delivered inside of a layout
                        // pass do not set the image immediately as it will trigger a requestLayout
                        // inside of a layout. Instead, defer setting the image by posting back to
                        // the main thread.
                        if (isImmediate && isInLayoutPass) {
                            post(new Runnable() {
                                @Override
                                public void run() {
                                    onResponse(response, false);
                                }
                            });
                            return;
                        }

                        if (response.getBitmap() != null) {
                            setImageBitmap(response.getBitmap());
                        } else if (mDefaultImageId != 0) {
                            setImageResource(mDefaultImageId);
                        }

                        if(mObserver!=null)
                        {
                            mObserver.onSuccess();
                        }
                    }
                });

        // update the ImageContainer to be the new bitmap container.
        mImageContainer = newContainer;
    }

    private void setDefaultImageOrNull() {
        if (mDefaultImageId != 0) {
            setImageResource(mDefaultImageId);
        } else {
            setImageBitmap(null);
        }
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        loadImageIfNecessary(true);
    }

    @Override
    protected void onDetachedFromWindow() {
        if (mImageContainer != null) {
            // If the view was bound to an image request, cancel it and clear
            // out the image from the view.
            mImageContainer.cancelRequest();
            setImageBitmap(null);
            // also clear out the container so we can reload the image if necessary.
            mImageContainer = null;
        }
        super.onDetachedFromWindow();
    }

    @Override
    protected void drawableStateChanged() {
        super.drawableStateChanged();
        invalidate();
    }
}

Ejemplo de uso:

 //set observer to view
 holder.image.setResponseObserver(new VolleyImageView.ResponseObserver() {
     @Override
     public void onError() {

     }

     @Override
     public void onSuccess() {

     }
 });

//and then load image
holder.image.setImageUrl(url, ImageCacheManager.getInstance().getImageLoader());

Answer 6

Usamos algo como esto:

imageView.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
    @Override
    public void onLayoutChange(View view, int i, int i2, int i3, int i4, int i5, int i6, int i7, int i8) {
        // the layout of the logo view changes at least twice: When it is added
        // to the parent and when the image has been loaded. We are only interested
        // in the second case and to find that case, we do this if statement

        if (imageView.getDrawable() != null) {
          doSomethingCoolHere();
        }

    }
});

No es necesariamente la pieza de código más hermosa, pero funciona (tm)

Answer 7

Listener<Bitmap> imageListener = new Listener<Bitmap>() {
    @Override
    public void onResponse(Bitmap response) {
        //This call back method is executed in the UI-Thread, when the loading is finished
        imageView.setImageBitmap(response); //example
    }
};
Response.ErrorListener errorListener = new Response.ErrorListener() {
    @Override
    public void onErrorResponse(VolleyError error) {
      //log your error
    }
};
//url, ListenerOnFinish, width, height, errorListener
ImageRequest getImageRequest = new ImageRequest(url, imageListener, 0, 0, null,errorListener);
requestQueue.add(getImageRequest);