如何将使用GZIP压缩的字符串从Java App发送到PHP Web服务

Question

I have this issue with GZIP compression:

I need to send by POST method a huge JSON string, which is too big to be accept like URL (Ex: http://localhost/app/send/ JSON STRING ENCODED BY BASE64 ), than it result in HTTP error 403

so, I need to compress my json and I found a way to do it with GZIP compression, which I can decompress with gzdecode() in PHP.

but it doesn't work...

my functions compress() and decompress() works fine inside my Java App, but when I send it to webservice, something goes wrong and gzdecode() doesn't work. I have no idea what I missing, I need some help

functions used in java app (client)

    public String Post(){
     String retorno = "";
     String u = compress(getInput());
     u = URLEncoder.encode(URLEncoder.encode(u, "UTF-8"));

     URL uri = new URL(url + u);

     HttpURLConnection conn = (HttpURLConnection) uri.openConnection();

     conn.setDoOutput(false);
     conn.setRequestMethod(getMethod());

     conn.setRequestProperty("Content-encoding", "gzip");
     conn.setRequestProperty("Content-type", "application/octet-stream");

     BufferedReader buffer = new BufferedReader(
                    new InputStreamReader((conn.getInputStream())));

     String r = "";
     while ((r = buffer.readLine()) != null) {
                retorno = r + "\n";
     }
     return retorno;
}

GZIP compress function (client)

public static String compress(String str) throws IOException {

        byte[] blockcopy = ByteBuffer
                .allocate(4)
                .order(java.nio.ByteOrder.LITTLE_ENDIAN)
                .putInt(str.length())
                .array();
        ByteArrayOutputStream os = new ByteArrayOutputStream(str.length());
        GZIPOutputStream gos = new GZIPOutputStream(os);
        gos.write(str.getBytes());
        gos.close();
        os.close();
        byte[] compressed = new byte[4 + os.toByteArray().length];
        System.arraycopy(blockcopy, 0, compressed, 0, 4);
        System.arraycopy(os.toByteArray(), 0, compressed, 4,
                os.toByteArray().length);

        return Base64.encode(compressed);

    }

method php used to receive a URL (server, using Slim/PHP Framework)

init::$app->post('/enviar/:obj/', function( $obj ) {
     $dec = base64_decode(urldecode( $obj ));//decode url and decode base64 tostring
     $dec = gzdecode($dec);//here is my problem, gzdecode() doesn't work
}

post method

public Sender() throws JSONException {   
    //
    url = "http://192.168.0.25/api/index.php/enviar/";
    method = "POST";
    output = true;
    //
}

Answer 1

As noticed in some of the comments.

1. Bigger data should be send as a POST request instead of GET. URL params should be used only for single variables. As you noticed the URL length is limited to few kB and it's not very good idea to send larger data this way (even though GZIP compressed).

2. Your GZIP compression code seems to be wrong. Please try this:

  public static String compress(String str) throws IOException {
    ByteArrayOutputStream os = new ByteArrayOutputStream(str.length());
    GZIPOutputStream gos = new GZIPOutputStream(os);
    gos.write(str.getBytes());
    os.close();
    gos.close();
    return Base64.encodeToString(os.toByteArray(),Base64.DEFAULT);
  }