Java-readLine()阻塞问题及解决过程

//用户发送消息的线程
class SentMessage extends Thread{
        private Socket socket;
        private BufferedWriter bw;
        private BufferedReader mysc;
        SentMessage(Socket socket){
            this.socket = socket;
            try {
                bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
                mysc = new BufferedReader(new InputStreamReader(System.in));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        @Override
        public void run(){
            try{
                while (true){
                    String mymessage = mysc.readLine();
                    bw.write(mymessage+"\n");
                    bw.flush();
                    if("bye".equals(mymessage)){
                        break;
                    }
                }
            }catch (IOException e){
                e.printStackTrace();
            }finally {
                try{
                    if(mysc!=null){
                        mysc.close();
                    }
                    if(bw!=null){
                        bw.close();
                    }
                }catch (IOException e){
                    e.printStackTrace();
                }
            }
        }
    }

//内置线程类用于接收消息，并广播
    class AcceptMessage extends Thread{
        private Socket clientsocket;
        private BufferedReader br;
        AcceptMessage(Socket clientsocket){
            this.clientsocket = clientsocket;
        }
        /**
         * 服务器将所有接收的消息广播（显示在每一个客户的聊天窗口中
         * 注意：如果这里不用线程，会出现问题，思考---其实就是readLine()阻塞的问题
         */
        private void tellEveryone(Socket socket){
            try{
                //先从发送消息的客户读内容
                br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                String message = br.readLine();
                chatArea.append("用户"+socket.getPort()+": "+message+"\n");
                //然后将内容广播到每一个客户接口
                Iterator<Socket> it = list.iterator();
                while (it.hasNext()){
                    Socket socket2 = it.next();
                    //对自己就不要广播了
                    if(socket!=socket2){
                        bw = new BufferedWriter(new OutputStreamWriter(socket2.getOutputStream()));
                        bw.write(socket2.getInetAddress().getHostAddress()+": "+message+"\n");
                        bw.flush();
                    }
                }
            }catch (IOException e){
                e.printStackTrace();
            }
        }
        @Override
        public void run(){
            while (true){
                //接收并广播
                tellEveryone(clientsocket);
            }
        }
    }