check gzip stream

CheckGZIPStream

package com.xqbase.java;

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

public class CheckGZIPStream {

    public static void main(String[] args) throws Exception {
        InputStream inputStream = new FileInputStream("");
        PushbackInputStream pushbackInputStream = new PushbackInputStream(inputStream, 2);
        System.out.println(isInputStreamGZIPCompressed(pushbackInputStream));
    }

    private static boolean isInputStreamGZIPCompressed(final PushbackInputStream inputStream) throws IOException {
        if (inputStream == null)
            return false;

        byte[] signature = new byte[2];
        int readStatus = inputStream.read(signature);
        inputStream.unread(signature);
        int streamHeader = ((int) signature[0] & 0xff) | ((signature[1] << 8) & 0xff00);
        return readStatus == 2 && GZIPInputStream.GZIP_MAGIC == streamHeader;
    }
}