套接字在发送后没有收到数据

我还是比较新手，所以我遇到了一个小问题

我有我的Android应用程序，通过套接字发送一个字节数组，然后服务器（也用java制作）接收数据，如果需要，它会将响应发送回客户端 .

在实践中，我得到的是：

• 服务器继续

• App连接到服务器

• App发送字节数组

• 服务器接收数据

• 服务器检查是否有任何要发回的消息
  如果是

• ，则发送数据

• App无法识别输入流

Client side

//infinite loop
        while(true) {
            //client has anything to be sent
            if (msg != null) {
                //open output stream
                OutputStream outputStream = socket.getOutputStream();
                DataOutputStream dataOutputStream = new DataOutputStream(outputStream);

                if (msg.length > 0) {
                    dataOutputStream.write(msg, 0, msg.length);
                    dataOutputStream.flush();
                    outputStream.flush();
                    //send message (byte array)
                }

                InputStream inputStream = socket.getInputStream();
                if (inputStream.available() > 0) {
                    //never gets in this statement
                    DataInputStream dataInputStream = new DataInputStream(inputStream);
                    String msg = dataInputStream.readUTF();
                    socket.shutdownInput();
                }
                disconnect();
            }
        }

Server side

try {
            //server inputstream
            InputStream inputStream = client.getInputStream();  
            //sucessfully goes in
            if(inputStream.available() > 0) {
                BufferedReader inReader = new BufferedReader(new InputStreamReader(inputStream));
                ByteArrayOutputStream output = new ByteArrayOutputStream();
                //receives all of this properly, no problems
                try (FileOutputStream fos = new FileOutputStream(filename)) {
                    int size = 1024;
                    int filesize = client.getReceiveBufferSize();
                    byte[] buffer = new byte[1024];

                    int bytesReceived;
                    while((bytesReceived = inputStream.read(buffer, 0, size)) > -1) {
                        fos.write(buffer, 0, bytesReceived);
                        output.write(buffer, 0, bytesReceived);
                    }
                    fos.close();
                }


                String message = frame.getMessage();
                if(message.length() > 0) {
                    try {
                        //goes in here, no problem
                        OutputStream outputStream = client.getOutputStream();
                        DataOutputStream dos = new DataOutputStream(outputStream);
                        dos.writeUTF(message);
                        //writes the utf properly no problem
                        dos.close();
                        outputStream.close();
                    } catch (IOException ex) {
                        Logger.getLogger(ReceiveDataThread.class.getName()).log(Level.SEVERE, null, ex);
                    }
                    System.out.println("Message '"+message+"' has been sent to " + frame.getConnection().getIp());
                    //all ok
                }
                client.close();
                client = null;
                Thread.currentThread().interrupt();
            }

        } catch (IOException ex) {
            Logger.getLogger(ReceiveDataThread.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

现在，为什么客户端没有收到服务器的UTF响应？