Java GzipInputStream GZIP can not read the whole file

GzipInputStream can only read a small portion of gzip file.

This is a bug for Java

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4691425

Reason: the gz/zip file is concatenated before. (e.g. you continuously append the gz/zip file)

Solutions:

Use following class "MultiMemberGZIPInputStream"
to replace "GzipInputStream" 

import java.io.InputStream;
import java.io.PushbackInputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;

/**
 * replace GZIPInputStream to read concatenated gz file

   FileInputStream fis = new FileInputStream(zipFileName);
   BufferedReader reader = new BufferedReader(new InputStreamReader(
        new MultiMemberGZIPInputStream(fis))); 
 */


public class MultiMemberGZIPInputStream extends GZIPInputStream {
  private MultiMemberGZIPInputStream parent;
  private MultiMemberGZIPInputStream child;
  private int size;
  private boolean eos;

  public MultiMemberGZIPInputStream(InputStream in, int size)
      throws IOException {
    // Wrap the stream in a PushbackInputStream…
    super(new PushbackInputStream(in, size), size);
    this.size = size;
  }

  public MultiMemberGZIPInputStream(InputStream in)
      throws IOException {
    // Wrap the stream in a PushbackInputStream…
    super(new PushbackInputStream(in, 1024));
    this.size = -1;
  }

  private MultiMemberGZIPInputStream(MultiMemberGZIPInputStream parent)
      throws IOException {
    super(parent.in);
    this.size = -1;
    this.parent = parent.parent == null ? parent : parent.parent;
    this.parent.child = this;
  }

  private MultiMemberGZIPInputStream(MultiMemberGZIPInputStream parent, int size)
      throws IOException {
    super(parent.in, size);
    this.size = size;
    this.parent = parent.parent == null ? parent : parent.parent;
    this.parent.child = this;
  }

  public int read(byte[] inputBuffer, int inputBufferOffset, int inputBufferLen)
      throws IOException {

    if (eos) {
      return -1;
    }
    if (this.child != null) {
      return this.child.read(inputBuffer, inputBufferOffset, inputBufferLen);
    }

    int charsRead = super.read(inputBuffer, inputBufferOffset, inputBufferLen);
    if (charsRead == -1) {
      // Push any remaining buffered data back onto the stream
      // If the stream is then not empty, use it to construct
      // a new instance of this class and delegate this and any
      // future calls to it…
      int n = inf.getRemaining() - 8;
      if (n > 0) {
        // More than 8 bytes remaining in deflater
        // First 8 are gzip trailer. Add the rest to
        // any un-read data…
        ((PushbackInputStream)this.in).unread(buf, len - n, n);
      } else {
        // Nothing in the buffer. We need to know whether or not
        // there is unread data available in the underlying stream
        // since the base class will not handle an empty file.
        // Read a byte to see if there is data and if so,
        // push it back onto the stream…
        byte[] b = new byte[1];
        int ret = in.read(b, 0, 1);
        if (ret == -1) {
          eos = true;
          return -1;
        } else {
          ((PushbackInputStream)this.in).unread(b, 0, 1);
        }
      }

      MultiMemberGZIPInputStream child;
      if (this.size == -1) {
        child = new MultiMemberGZIPInputStream(this);
      } else {
        child = new MultiMemberGZIPInputStream(this, this.size);
      }
      return child.read(inputBuffer, inputBufferOffset, inputBufferLen);
    } else {
      return charsRead;
    }
  }
}