RTPConnector实现类RTPJxtaMulticastSocketAdapter的问题

我底层传输使用JxtaMulticastSocket，以便能在JXTA平台使用JMF的RTP支持。

 在RTPConnector的实现类中有

    /**
     * An inner class to implement an PushSourceStream based on UDP sockets.
     */
    class SockInputStream extends Thread implements PushSourceStream {

        JxtaMulticastSocket sock;
        // ... other declariation

        public SockInputStream(JxtaMulticastSocket sock) {
            this.sock = sock;
        }

        @Override
        public int read(byte buffer[], int offset, int length) {
            byte[] buf = new byte[length];
            DatagramPacket p = new DatagramPacket(buf, offset, length);
            try {
                sock.receive(p);
                byte[] data = p.getData();
                System.arraycopy(data, 0, buffer, offset, p.getLength());
            } catch (IOException e) {
                return -1;
            }
            synchronized (this) {
                dataRead = true;
                notify();
            }
            return p.getLength();
        }

        // ... other function ...
    }

 上面是正常的代码，下面贴的是不正常的代码，是我参考其他资料写出的

    /**
     * An inner class to implement an PushSourceStream based on UDP sockets.
     */
    class SockInputStream extends Thread implements PushSourceStream {

        DatagramSocket sock;
        // ... other declaration ...

        public SockInputStream(DatagramSocket sock, InetAddress addr, int port) {
            this.sock = sock;
            // ...
        }

        public int read(byte buffer[], int offset, int length) {
            DatagramPacket p = new DatagramPacket(buffer, offset, length, addr, port);
            try {
                sock.receive(p);
            } catch (IOException e) {
                return -1;
            }
            synchronized (this) {
                dataRead = true;
                notify();
            }
            return p.getLength();
        }

        // ... other function ...
    }

比较一下可以发现不同之处。

 这个问题让我头疼了2天