BufferedReader.read blocks when wrapping InflaterInputStream

Question

Hello,
I'm currently doing client - server communication using http chunked transfer encoding. Furthermore chunks sent are compressed using zlib in sync_flush mode. The client code reads data from an InputStream using the following code snippet:
URLConnection conn = new URL(anUrl).openConnection();
BufferedReader reader = new BufferedReader(new InputStreamReader(new InflaterInputStream(conn.getInputStream())));
int read = 0;
while ((read = reader.read()) != -1)
  System.out.println((char)read);When running the above code snippet, the client will not read on a per chunk basis, but will block until receiving EOF from server. When using BufferedInputStream instead everything works fine.
Does anybody know how to overcome this problem?
Thanks!

Answer 1

Yes you are right!
But as i said, using BufferInputStream instead gives an important different behaviour. In this case read doesn't block until the underlying stream receives EOF. The call to read will immediately return bytes when on the server side a chunk of data has been send to the output stream.
When investigating why BufferedReader blocks, i found that StreamDecoder, a class member of InputStreamReader uses the following code to implement reading from the underlying InflaterInputStream.
  301       int implRead(char[] cbuf, int off, int end) throws IOException {
  315           for (;;) {
  316           CoderResult cr = decoder.decode(bb, cb, eof);
  317           if (cr.isUnderflow()) {
  318               if (eof)
  319                   break;
  320               if (!cb.hasRemaining())
  321                   break;
  322               if ((cb.position() > 0) && !inReady())
  323                   break;          // Block at most once
  324               int n = readBytes();
  325               if (n < 0) {
  326                   eof = true;
  327                   if ((cb.position() == 0) && (!bb.hasRemaining()))
  328                       break;
  329                   decoder.reset();
  330               }
  331               continue;
  332           }
  ...The part that will prevent BufferedReader from not blocking is "!inReady()" at line 322. This method calls, among other things, available on the underlying InflaterInputStream. But as stated there, InflaterInputStream will always return 1 until EOF and "Programs should not count on this method to return the actual number of bytes that could be read without blocking".
So in my opinion StreamDecoder's implementation won't be able to handle chunked encoding "out of the box".