Socket客户端给服务端发信息，服务端显示为null,该怎么处理

Socket socket = server.accept();                    BufferedReader bfr = new BufferedReader(new InputStreamReader(socket.getInputStream()));                    StringBuffer messageContent = new StringBuffer();                    while(bfr.readLine() != null)                    {                        messageContent.append(bfr.readLine());                    }                    StringBuffer messageRecord = new StringBuffer(showMessage.getText());                    messageRecord.append(messageContent.toString());                    messageRecord.append("\n");                    showMessage.setText(messageRecord.toString());

Socket socket = new Socket("127.0.0.1",8889);                PrintWriter out = new PrintWriter(socket.getOutputStream(),true);                                out.println(messageContent);                out.flush();                out.close();