如何使用Volley库和NetworkImageView在setImageUrl上完成callback?

我正在尝试Google的新Volley库,当我使用这个方法setImageUrl时,它看起来很清晰并快速加载图像

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

我想添加一个callback/监听器方法,当加载完成时会启动,所以我可以删除progressBar视图并显示图像。 这是Universal Image LoaderPicasso图书馆中的一个选项,但由于某种原因,我找不到在Volley这样做的方法,尝试谷歌不同的选项,但到目前为止还没有find任何参考。

是否有代码示例来说明如何完成?

提前致谢。

Solutions Collecting From Web of "如何使用Volley库和NetworkImageView在setImageUrl上完成callback?"

你可以使用这个视图,而不是谷歌的视图(我从它复制的来源,并作出一些更改):

 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(); } } 

用法示例:

  //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()); 

我这样做: –

  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) { } }); 

我们用这样的东西:

 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(); } } }); 

它不一定是最美丽的一段代码,但它的作品(tm)

另一种依赖于了解NetworkImageView内部的方法是inheritanceNetworkImageView,以监视mErrorImageId的应用。

 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); } } 

您还必须将布局文件中的NetworkImageViewreplace为ManagedNetworkImageView。

有点不好意思,但是当NetworkImageView已经是你select的解决scheme的时候,就做这个工作。

 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); 

另一种方法(类似于上面@Simulant的代码)是在你的xml中使用一个普通的ImageView,然后使用Volley.ImageRequest进行图像请求。 如果你使用Google推荐的Singleton模式,它会看起来像这样:

 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); 

顺便说一句:确保您使用常规ImageView而不是NetworkImageView,否则图像将无法正常显示。