I tried to create byte array blocks from file whil the process was still using the file for writing. Actually I am storing video into file and I would like to create chunks from the same file while recording.
The following method was supposed to read blocks of bytes from file:
private byte[] getBytesFromFile(File file) throws IOException{
InputStream is = new FileInputStream(file);
long length = file.length();
int numRead = 0;
byte[] bytes = new byte[(int)length - mReadOffset];
numRead = is.read(bytes, mReadOffset, bytes.length - mReadOffset);
if(numRead != (bytes.length - mReadOffset)){
throw new IOException("Could not completely read file " + file.getName());
}
mReadOffset += numRead;
is.close();
return bytes;
}
But the problem is that all array elements are set to 0 and I guess it is because the writing process locks the file.
I would bevery thankful if anyone of you could show any other way to create file chunks while writing into file.
Solved the problem:
private void getBytesFromFile(File file) throws IOException {
FileInputStream is = new FileInputStream(file); //videorecorder stores video to file
java.nio.channels.FileChannel fc = is.getChannel();
java.nio.ByteBuffer bb = java.nio.ByteBuffer.allocate(10000);
int chunkCount = 0;
byte[] bytes;
while(fc.read(bb) >= 0){
bb.flip();
//save the part of the file into a chunk
bytes = bb.array();
storeByteArrayToFile(bytes, mRecordingFile + "." + chunkCount);//mRecordingFile is the (String)path to file
chunkCount++;
bb.clear();
}
}
private void storeByteArrayToFile(byte[] bytesToSave, String path) throws IOException {
FileOutputStream fOut = new FileOutputStream(path);
try {
fOut.write(bytesToSave);
}
catch (Exception ex) {
Log.e("ERROR", ex.getMessage());
}
finally {
fOut.close();
}
}
If it were me, I would have it chunked by the process/thread writing to the file. This is how Log4j seems to do it, at any rate. It should be possible to make an OutputStream
which automatically starts writing to a new file every N bytes.
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