服务器压缩有效负载时出现websocket协议错误

Question

    public void sendMessageDeflated(String rxMessage, OutputStream streamOut) {

    System.out.println("Message back to client is: " + rxMessage);

    // And then compress the response and send it out.
    Deflater compressor = new Deflater(Deflater.DEFLATED);
    try {
        int headerLength = 2;
        byte unzippedMsg[] = rxMessage.getBytes("UTF-8");
        compressor.setInput(unzippedMsg);
        compressor.finish();
        byte zippedMsg[] = new byte[2048];  // Nasty constant but will have to do for now.
        int toCompressLength = unzippedMsg.length;
        int compLength = compressor.deflate(zippedMsg, headerLength, zippedMsg.length - headerLength);
        compressor.end();

        zippedMsg[0] = (byte)0xC1; // FIN bit, compression plus opcode for TEXT MESSAGE
        zippedMsg[1] = (byte)((byte)0x00 | (byte)compLength); // No mask on return data.

        streamOut.write(zippedMsg, 0, compLength + headerLength);

    } catch ( IOException ioEx ) {
        // TBD
        System.out.println("IOException: " + ioEx.toString());
    } catch ( Exception ex ) {
        // TBD
        System.out.println("IOException: " + ex.toString());
    }
}

Gzip

    public void sendMessageGZipped(String rxMessage, OutputStream streamOut) {
    // Do something with the message here...

    System.out.println("Message back to client is: " + rxMessage);

    // And then compress the response and send it out.
    try {
        int headerLength = 2;
        byte unzippedMsg[] = rxMessage.getBytes("UTF-8");
        int toCompressLength = unzippedMsg.length;

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        GZIPOutputStream gzipOut = new GZIPOutputStream(baos);
        gzipOut.write(unzippedMsg, 0, toCompressLength);
        gzipOut.close();
        byte[] payload = baos.toByteArray();

        byte header[] = new byte[32];
        header[0] = (byte)0xC1; // FIN bit plus opcode for TEXT MESSAGE
        header[1] = (byte)((byte)0x00 | (byte)payload.length); // No mask on return data.

        streamOut.write(header, 0, 2);
        streamOut.write(payload);

    } catch ( IOException ioEx ) {
        // TBD
        System.out.println("IOException: " + ioEx.toString());
    } catch ( Exception ex ) {
        // TBD
        System.out.println("IOException: " + ex.toString());
    }
}

我尝试切换到二进制操作码，认为可能压缩文本=binary，但这不起作用。我真的看不出我做错了什么或者错过了什么。此实现不包括跨越消息的滑动压缩窗口。我想响应头说明了这一点。帮助感激地接受了。

Answer 1

我最终通过构建客户端websocket代码解决了这个问题，并看到当它试图膨胀消息时抛出的异常：“无效存储块长度”。这让我写到了这篇文章：Java解压缩字节数组，它讨论了Deflate是否能够使用zlib包装器进行压缩。因此将processMessage2中的一行代码从上面的示例代码更改为...

        Deflater compressor = new Deflater(Deflater.DEFLATED, true);

…它将“nowrap”设置为true。

Chrome浏览器客户端在其报头中声称支持gzip。如果我把它弄好了，我会回到这里，把答案也贴出来。