问题
How can you read GZIP file in Android located in the "ASSETS" (or resources/raw) folder?
I have tried the following code, but my stream size is always 1.
GZIPInputStream fIn = new GZIPInputStream(mContext.getResources().openRawResource(R.raw.myfilegz));
int size = fIn.available();
for some reason the size is always 1. But if Idon't GZIP the file, it works fine.
NOTE: Using Android 1.5
回答1:
I met the same problem when reading a gz file from assets folder.
It's caused by the file name of the gz file. Just renaming yourfile.gz to other name like yourfile.bin. It seems Android build system would decompress a file automatically if it thought it's a gz.
回答2:
public class ResLoader {
/**
* @param res
* @throws IOException
* @throws FileNotFoundException
* @throws IOException
*/
static void unpackResources() throws FileNotFoundException, IOException {
final int BUFFER = 8192;
android.content.res.Resources t = TestingE3d.mContext.getResources();
InputStream fis = t.openRawResource(R.raw.resources);
if (fis == null)
return;
ZipInputStream zin = new ZipInputStream(new BufferedInputStream(fis,
BUFFER));
ZipEntry entry;
while ((entry = zin.getNextEntry()) != null) {
int count;
FileOutputStream fos = TestingE3d.mContext.openFileOutput(entry
.getName(), 0);
BufferedOutputStream dest = new BufferedOutputStream(fos, BUFFER);
byte data[] = new byte[BUFFER];
while ((count = zin.read(data, 0, BUFFER)) != -1) {
dest.write(data, 0, count);
// Log.v("NOTAG", "writing "+count + " to "+entry.getName());
}
dest.flush();
dest.close();
}
zin.close();
}
}
R.raw.resources is a zip file - this class will decompress all files in that zip to your local folder. I use this for NDK.
you can access your fils from ndk through: /data/data//files/
package = package where ResLoader resides filename = one of files that is in raw/resources.zip
回答3:
this is the documented behavior of InflaterInputStream.available:
http://java.sun.com/javase/6/docs/api/java/util/zip/InflaterInputStream.html#available()
Returns 0 after EOF has been reached, otherwise always return 1.
abusing available is a common mistake --- in no case can you assume that it tells you the length of a file (though it sometimes happens to do so, as you've noticed). you want to keep calling read(byte[], int, int) until it returns 0. if you want the length to allocate a byte[] up front, you probably want to create a ByteArrayOutputStream and write to that each time you read, and then get a byte[] from that when you exit the loop. this works for all InputStreams in all cases.
回答4:
It seems that the build system treats .gz files as a special case, even when it's included as a raw resource. Rename the .gz file to have a different extension, say .raw or .bin .
Valid at least for Android Studio 2.2 . I can't find any docs to confirm this is expected behaviour or, better, how to prevent it, but changing the extension at least works around the problem.
回答5:
What happens if you use AssetManager
instead of Resources
? Example:
InputStream is = mContext.getAssets().open("myfilegz");
GZIPInputStream fIn = new GZIPINputStream(is);
Internally, Resources
is just calling AssetManager
; I wonder if somewhere along the way it musses things up.
回答6:
Try looking at the source for Translate from apps-for-android open source project and see if that helps at all.
They use GZIPInputStream on a raw file in their selectRandomWord() function [line 326] (source pasted below)
public void selectRandomWord() {
BufferedReader fr = null;
try {
GZIPInputStream is =
new GZIPInputStream(getResources().openRawResource(R.raw.dictionary));
来源:https://stackoverflow.com/questions/2364185/android-read-a-gzip-file-in-the-assets-folder