Compressing a string using GZIPOutputStream

问题

I want to zip my string values. These string values should be same as .net zipped strings.

I wrote Decompress method and when I send a .net zipped string to it, it works correctly. But the Compress method does not work correctly.

public static String Decompress(String zipText) throws IOException {
    int size = 0;
    byte[] gzipBuff = Base64.decode(zipText);

    ByteArrayInputStream memstream = new ByteArrayInputStream(gzipBuff, 4,
            gzipBuff.length - 4);
    GZIPInputStream gzin = new GZIPInputStream(memstream);

    final int buffSize = 8192;
    byte[] tempBuffer = new byte[buffSize];
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    while ((size = gzin.read(tempBuffer, 0, buffSize)) != -1) {
        baos.write(tempBuffer, 0, size);
    }
    byte[] buffer = baos.toByteArray();
    baos.close();

    return new String(buffer, "UTF-8");
}

-

public static String Compress(String text) throws IOException {

    byte[] gzipBuff = EncodingUtils.getBytes(text, "UTF-8");

    ByteArrayOutputStream bs = new ByteArrayOutputStream();

    GZIPOutputStream gzin = new GZIPOutputStream(bs);

    gzin.write(gzipBuff);

    gzin.finish();
    bs.close();

    byte[] buffer = bs.toByteArray();

    gzin.close();

    return Base64.encode(buffer);
}

For example when I send "BQAAAB+LCAAAAAAABADtvQdgHEmWJSYvbcp7f0r1StfgdKEIgGATJNiQQBDswYjN5pLsHWlHIymrKoHKZVZlXWYWQMztnbz33nvvvffee++997o7nU4n99//P1xmZAFs9s5K2smeIYCqyB8/fnwfPyLmeVlW/w+GphA2BQAAAA==" to Decompress method It returns the string "Hello", but when I send "Hello" to Compress method It returns "H4sIAAAAAAAAAMtIzcnJBwCGphA2BQAAAA==".

What is the problem in Compress method????

回答1:

Check Use Zip Stream and Base64 Encoder to Compress Large String Data

about how to use GZIPOutputStream/GZIInputStream and Base64 Encoder and Decoder to compress and uncompress large string data, so it can be passed as text in http response.

public static String compressString(String srcTxt) throws IOException {
  ByteArrayOutputStream rstBao = new ByteArrayOutputStream();
  GZIPOutputStream zos = new GZIPOutputStream(rstBao);
  zos.write(srcTxt.getBytes());
  IOUtils.closeQuietly(zos);

  byte[] bytes = rstBao.toByteArray();
  return Base64.encodeBase64String(bytes);
}

Or we can use Use Zip Stream and Base64 Encoder to Compress Large String Data to avoid load whole string into memory.

public static String uncompressString(String zippedBase64Str) throws IOException {
  String result = null;
  byte[] bytes = Base64.decodeBase64(zippedBase64Str);
  GZIPInputStream zi = null;
  try {
    zi = new GZIPInputStream(new ByteArrayInputStream(bytes));
    result = IOUtils.toString(zi);
  } finally {
    IOUtils.closeQuietly(zi);
  }
    return result;
}

回答2:

I have tried with java vm i suppose the result is the same. Use this line at the end of your Compress method :

return new String(base64.encode(buffer), "UTF-8");

来源：https://stackoverflow.com/questions/6747454/compressing-a-string-using-gzipoutputstream