[java] java 로 gzip 압축 및 풀기

1. gzip 압축하기

public byte[] compress(String value) throws Exception {

    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    GZIPOutputStream gzipOutStream =new GZIPOutputStream(
             new BufferedOutputStream(byteArrayOutputStream));
    gzipOutStream.write(value.getBytes());
    gzipOutStream.finish();
    gzipOutStream.close();

    return byteArrayOutputStream.toByteArray();
}

public static byte[] compress(final String str) throws IOException {
    if ((str == null) || (str.length() == 0)) {
      return null;
    }
    ByteArrayOutputStream obj = new ByteArrayOutputStream();
    GZIPOutputStream gzip = new GZIPOutputStream(obj);
    gzip.write(str.getBytes("UTF-8"));
    gzip.flush();
    gzip.close();
    return obj.toByteArray();
  }

 

2. gzip 압축 풀기

public String decompress(byte[] value) throws Exception {

    ByteArrayOutputStream outStream = new ByteArrayOutputStream();

    GZIPInputStream gzipInStream = new GZIPInputStream(
                new BufferedInputStream(new ByteArrayInputStream(value)));

    int size = 0;
    byte[] buffer = new byte[1024];
    while ( (size = gzipInStream.read(buffer)) > 0 ) {
        outStream.write(buffer, 0, size);
    }
    outStream.flush();
    outStream.close();

    return new String(outStream.toByteArray());
}

public static String decompress(final byte[] compressed) throws IOException {
    final StringBuilder outStr = new StringBuilder();
    if ((compressed == null) || (compressed.length == 0)) {
      return "";
    }
    if (isCompressed(compressed)) {
      final GZIPInputStream gis = new GZIPInputStream(new ByteArrayInputStream(compressed));
      final BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(gis, "UTF-8"));

      String line;
      while ((line = bufferedReader.readLine()) != null) {
        outStr.append(line);
      }
    } else {
      outStr.append(compressed);
    }
    return outStr.toString();
  }

  public static boolean isCompressed(final byte[] compressed) {
    return (compressed[0] == (byte) (GZIPInputStream.GZIP_MAGIC)) && (compressed[1] == (byte) (GZIPInputStream.GZIP_MAGIC >> 8));
  }