How To Use universal image loader offline caching?

问题

Is it possible to catch offline using universal image loader? If possible, how to use it? Using configs? How To Set Download Directory manually?

out of memory erroron load huge images :

my codes :

DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder()
            .cacheOnDisc(true).cacheInMemory(true)
            .imageScaleType(ImageScaleType.IN_SAMPLE_INT)
            .displayer(new FadeInBitmapDisplayer(300)).build();
    ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(G.appConfigs.context)
            .defaultDisplayImageOptions(defaultOptions)
            .memoryCacheExtraOptions(480, 800) // default = device screen dimensions
            .diskCacheExtraOptions(480, 800, null)
            .memoryCache(new WeakMemoryCache())
            .memoryCache(new LruMemoryCache(2 * 1024 * 1024))
            .memoryCacheSize(2 * 1024 * 1024)
            .discCacheSize(300 * 1024 * 1024)
            .build();
    ImageLoader.getInstance().init(config);
    // END - UNIVERSAL IMAGE LOADER SETUP

    ImageLoader imageLoader = ImageLoader.getInstance();

        DisplayImageOptions options = new DisplayImageOptions.Builder().cacheInMemory(true)
            .cacheOnDisc(true).resetViewBeforeLoading(true)
            .showImageForEmptyUri(R.drawable.no_pic)
            .showImageOnFail(R.drawable.load_failed)
            .showImageOnLoading(R.drawable.img_thumb).build();

    //download and display image from url
    imageLoader.displayImage(imgURL, img, options);

how to resolve it ?

回答1:

You can use the ImageLoaderConfiguration.Builder class to customize disk caching. This includes the methods:

diskCacheExtraOptions()
diskCacheSize() (in bytes).
diskCacheFileCount()
diskCacheFileNameGenerator()
and some others.

Or you can just use diskCache(DiskCache) to provide a custom class for implementing offline caching.

From the example in the Configuration section of the wiki:

File cacheDir = StorageUtils.getCacheDirectory(context);
ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(context)
    .memoryCacheExtraOptions(480, 800) // default = device screen dimensions
    .diskCacheExtraOptions(480, 800, null)
    .taskExecutor(...)
    .taskExecutorForCachedImages(...)
    .threadPoolSize(3) // default
    .threadPriority(Thread.NORM_PRIORITY - 1) // default
    .tasksProcessingOrder(QueueProcessingType.FIFO) // default
    .denyCacheImageMultipleSizesInMemory()
    .memoryCache(new LruMemoryCache(2 * 1024 * 1024))
    .memoryCacheSize(2 * 1024 * 1024)
    .memoryCacheSizePercentage(13) // default
    .diskCache(new UnlimitedDiscCache(cacheDir)) // default
    .diskCacheSize(50 * 1024 * 1024)
    .diskCacheFileCount(100)
    .diskCacheFileNameGenerator(new HashCodeFileNameGenerator()) // default
    .imageDownloader(new BaseImageDownloader(context)) // default
    .imageDecoder(new BaseImageDecoder()) // default
    .defaultDisplayImageOptions(DisplayImageOptions.createSimple()) // default
    .writeDebugLogs()
    .build();

回答2:

But if you restart your device or clean your cache by anyway it will not work offline as the cached files will be deleted.
To Show offline images you have to download images on sd-card to a specific folder and have to pick from there in case on offline.

回答3:

Don't Know much about such lib. but you can use the following method to download your images. Just Call it from an Async. Task and pass your url.

private File root = Environment.getExternalStorageDirectory();
private File dir = new File(root.getAbsolutePath() + "/ImageFolder");

private void downloadFile(String url) throws Exception {
    URL ur = new URL(url);
    String fileName = url.substring(url.lastIndexOf("/") + 1);
    File file = new File(dir, fileName);
    URLConnection uconn = ur.openConnection();
    InputStream is = uconn.getInputStream();
    BufferedInputStream bufferinstream = new BufferedInputStream(is);
    ByteArrayBuffer baf = new ByteArrayBuffer(5000);
    int current = 0;
    while ((current = bufferinstream.read()) != -1) {
        baf.append((byte) current);
    }
    FileOutputStream fos = new FileOutputStream(file);
    fos.write(baf.toByteArray());
    fos.flush();
    fos.close();
}

回答4:

Universal Image Loader is one perfect library to load async your images. You can use @matiash answer to setup library configuration and then with

ImageLoader.getInstance().init(config);

you can apply them to the ImageLoader instance. After that if you have internet connection at the begin of your application, Universal Image Loader will download and cache all your images, on the places where you use loading of those images with Universal Image Loader library. The next time when you load same images, Universal Image Loader will get them from the cache, which means you don't need to have any internet connection(can work offline). The problem came when somebody is installing your application and trying to start using it for the first time, and if he doesn't have internet connection. Then Universal Image Loader will try to load your images from the web server and cache them to the storage, but it will fail because you don't have internet connection. That's why Universal Image Loader has a class like DisplayImageOptions :

new DisplayImageOptions.Builder()

which allow you to setup what should happen when there is a problem with loading your images. You can use for this purpose methods like:

.showImageOnLoading(R.drawable.default_image)
.showImageForEmptyUri(R.drawable.default_image)
.showImageOnFail(R.drawable.default_image)

Here is an example how you can use it:

DisplayImageOptions imageOptions = new DisplayImageOptions.Builder()
    .showImageOnLoading(getImageLoaderDefaultImage())
    .showImageForEmptyUri(getImageLoaderDefaultImage())
    .showImageOnFail(getImageLoaderDefaultImage())
    .cacheInMemory(true)
    .cacheOnDisk(true)
    .considerExifParams(true)
    .build();

Method getImageLoaderDefaultImage():

private int getImageLoaderDefaultImage(){ return R.drawable.default_img;}

And here is how to use Image Loader when you want to load image:

ImageLoader.getInstance().displayImage("image url", myImageView,imageOptions);

回答5:

If you are using Xamarin : Add Below code in OnCreateView or similar is available in Java also.

DisplayImageOptions options = new DisplayImageOptions.Builder().CacheInMemory(true).CacheOnDisk(true).Build();
ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this.Context).DefaultDisplayImageOptions(options).Build();
ImageLoader.Instance.Init(config);

Add below line of code, when loading image

ImageLoader imageLoader = ImageLoader.Instance;
imageLoader.DisplayImage(imgURL, imageSource);

来源：https://stackoverflow.com/questions/25968252/how-to-use-universal-image-loader-offline-caching

标签

android

universal-image-loader

offline-caching