How to store large blobs in an android content provider?

Question

I have some large files (images and video) which I need to store in a content provider. The android documentation indicates...

If you are exposing byte data that's too big to put in the table itself — such as a large bitmap file — the field that exposes the data to clients should actually contain a content: URI string. This is the field that gives clients access to the data file. The record should also have another field, named "_data" that lists the exact file path on the device for that file. This field is not intended to be read by the client, but by the ContentResolver. The client will call ContentResolver.openInputStream() on the user-facing field holding the URI for the item. The ContentResolver will request the "_data" field for that record, and because it has higher permissions than a client, it should be able to access that file directly and return a read wrapper for the file to the client. -- http://developer.android.com/guide/topics/providers/content-providers.html#creating

I am having some difficulty finding an example. In particular I wish to use the bitmap in the context an ImageView. Consider the following code quasi-code (it doesn't work)...

ImageView iv = ....
String iconUri = cursor.getString(cursor.getColumnIndex(Table.ICON));
iv.setImageURI(Uri.parse(iconUri));

Observations/Problems...

1. How can the stored/recovered uri be reconstructed correctly? (it is text in the table)

2. The setImageURI implementation makes use of the content resolve openInputStream so this should work.

   String scheme = mUri.getScheme(); ... } else if (ContentResolver.SCHEME_CONTENT.equals(scheme) || ContentResolver.SCHEME_FILE.equals(scheme)) { try { d = Drawable.createFromStream( mContext.getContentResolver().openInputStream(mUri), null);

--frameworks/base/core/java/android/widget/ImageView.java

I got it working. I took a hint from the MediaStore and MediaProvider. The files which contain the data are named based on the content provider (directory), the column name, the row id and the media type. The content resolver then acquires the file descriptor like so...

Uri iconUri = Uri.withAppendedPath(Table.getUri(cursor), Table.ICON);
ib.setImageURI(iconUri);

...and the content provider responds in kind...

@Override
public ParcelFileDescriptor openFile (Uri uri, String mode) {
int imode = 0;
if (mode.contains("w")) imode |= ParcelFileDescriptor.MODE_WRITE_ONLY;
if (mode.contains("r")) imode |= ParcelFileDescriptor.MODE_READ_ONLY;
if (mode.contains("+")) imode |= ParcelFileDescriptor.MODE_APPEND;
List<String> pseg = uri.getPathSegments();
if (pseg.size() < 3) return null;

try {
    File filePath = filePathFromRecord(pseg.get(2), pseg.get(1));
    return ParcelFileDescriptor.open(filePath, imode);
} catch (FileNotFoundException e) {
    e.printStackTrace();
}
return null;
}