I have a method like
public void put(@Nonnull final InputStream inputStream, @Nonnull final String uniqueId) throws PersistenceException {
// a.) create gzip of inputStream
final GZIPInputStream zipInputStream;
try {
zipInputStream = new GZIPInputStream(inputStream);
} catch (IOException e) {
e.printStackTrace();
throw new PersistenceException("Persistence Service could not received input stream to persist for " + uniqueId);
}
I wan to convert the inputStream
into zipInputStream
, what is the way to do that?
converting Java Streams to me are really confusing and I do not make them right
The GZIPInputStream
is to be used to decompress an incoming InputStream
. To compress an incoming InputStream
using GZIP, you basically need to write it to a GZIPOutputStream
.
You can get a new InputStream
out of it if you use ByteArrayOutputStream
to write gzipped content to a byte[]
and ByteArrayInputStream
to turn a byte[]
into an InputStream
.
So, basically:
public void put(@Nonnull final InputStream inputStream, @Nonnull final String uniqueId) throws PersistenceException {
final InputStream zipInputStream;
try {
ByteArrayOutputStream bytesOutput = new ByteArrayOutputStream();
GZIPOutputStream gzipOutput = new GZIPOutputStream(bytesOutput);
try {
byte[] buffer = new byte[10240];
for (int length = 0; (length = inputStream.read(buffer)) != -1;) {
gzipOutput.write(buffer, 0, length);
}
} finally {
try { inputStream.close(); } catch (IOException ignore) {}
try { gzipOutput.close(); } catch (IOException ignore) {}
}
zipInputStream = new ByteArrayInputStream(bytesOutput.toByteArray());
} catch (IOException e) {
e.printStackTrace();
throw new PersistenceException("Persistence Service could not received input stream to persist for " + uniqueId);
}
// ...
You can if necessary replace the ByteArrayOutputStream
/ByteArrayInputStream
by a FileOuputStream
/FileInputStream
on a temporary file as created by File#createTempFile()
, especially if those streams can contain large data which might overflow machine's available memory when used concurrently.