ImageContentProvider.java

public class ImageContentProvider extends ContentProvider {

	private static final String URI_PREFIX = "content://com.xianguo.image/";

	public static String constructUri(String imageUrl) {
		return URI_PREFIX + Uri.encode(imageUrl);
	}

	public static String deconstructUri(String imageUrl) {
		if (imageUrl == null || !imageUrl.startsWith(URI_PREFIX)) {
			return imageUrl;
		}
		imageUrl = imageUrl.substring(URI_PREFIX.length());
		return Uri.decode(imageUrl);
	}

	public static String deconstructUri(Uri uri) {
		String imageUrl = uri.toString();
		return deconstructUri(imageUrl);
	}

	@Override
	public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {
		String imageUrl = deconstructUri(uri);
		ImageCache imageCache = ImageCache.getInstance(getContext());

		if (!imageCache.containsInDisk(imageUrl)) {
			byte[] imageData = downloadImage(imageUrl);
			if (imageData != null) {
				imageCache.cacheToDisk(imageUrl, imageData);
			}
		}
		String path = imageCache.getFilePathInDisk(imageUrl);
		if (path != null) {
			File file = new File(path);
			return ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
		}
		return null;
	}

	/**
	 * Download From Internet
	 * @param imageUrl
	 */
	protected byte[] downloadImage(String imageUrl) {
		try {
			return HttpClient.doRequest(imageUrl, null);
		} catch (Throwable e) {
			e.printStackTrace();
		}
		return null;
	}

	@Override
	public boolean onCreate() {
		return true;
	}

	@Override
	public int delete(Uri uri, String s, String[] as) {
		throw new UnsupportedOperationException("Not supported by this provider");
	}

	@Override
	public String getType(Uri uri) {
		throw new UnsupportedOperationException("Not supported by this provider");
	}

	@Override
	public Uri insert(Uri uri, ContentValues contentvalues) {
		throw new UnsupportedOperationException("Not supported by this provider");
	}

	@Override
	public Cursor query(Uri uri, String[] as, String s, String[] as1, String s1) {
		throw new UnsupportedOperationException("Not supported by this provider");
	}

	@Override
	public int update(Uri uri, ContentValues contentvalues, String s, String[] as) {
		throw new UnsupportedOperationException("Not supported by this provider");
	}

}