Java套接字服务器客户端双向聊天程序未获得预期结果

我是JavaNIO新手，我正在使用NIO2编写一个简单的服务器-客户机双向通信程序。服务器和客户端正在本地运行。我无法得到我期望的结果，有人能帮我检查一下代码吗？非常感谢

服务器端：

public class Server 
{
    public static void main( String[] args )
    {
        try (AsynchronousServerSocketChannel server = AsynchronousServerSocketChannel.open()) {

            server.bind(new InetSocketAddress("127.0.0.1", 2001));
            Future<AsynchronousSocketChannel> acceptCon = server.accept();
            AsynchronousSocketChannel client = acceptCon.get(20, TimeUnit.SECONDS);

            if ((client != null) && (client.isOpen())) {
                Thread.sleep(50); // *** if I do not sleep 50 milsec here, I will get empty string
                ByteBuffer buffer = ByteBuffer.allocate(1024);
                Future<Integer> readval = client.read(buffer);
                String msg = new String(buffer.array()).trim();
                System.out.println("Received from client: " + msg);

                readval.get();
                buffer.flip();
                String str = "I am fine! Thanks.";

                Future<Integer> writeVal = client.write(ByteBuffer.wrap(str.getBytes()));
                System.out.println("Writing back to client: " + str);
                writeVal.get();
                buffer.clear();
            }
            client.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

客户：

Writing to server: Hello! How are you?
Received from server: I am fine! Thanks.

Writing to server: Hello! How are you?
Received from server: I am fine! Thanks.(If do not use sleep, empty string here)

但是，我得到了：

Received from client: Hello! How are you? | (If do not use sleep, it is empty string here)
Writing back to client: I am fine! Thanks.

客户：

Writing to server: Hello! How are you?
Received from server: I am fine! Thanks.

Writing to server: Hello! How are you?
Received from server: I am fine! Thanks.(If do not use sleep, empty string here)

我的问题是： 1.我使用的是Eclipse，当我通过断点调试服务器和客户机项目时，我得到了预期的结果。但是，当我在客户端运行服务器和客户端时，如果我不使用Thread.sleep（100），它将显示“Received from server:”的空字符串，为什么？ 2.对于服务器端，如果我在50毫秒内没有睡眠，大多数情况下，“Received from client:”的输出也将是空字符串，有什么提示吗

非常感谢你们的帮助。

客户端。读取（缓冲区）是一个异步操作。future上的

get

调用确保操作已成功完成

ByteBuffer buffer = ByteBuffer.allocate(1024);
Future<Integer> readval = client.read(buffer);
readval.get();
String msg = new String(buffer.array()).trim();
System.out.println("Received from client: " + msg);

ByteBuffer buffer=ByteBuffer.allocate（1024）；
Future readval=client.read（缓冲区）；
readval.get（）；
String msg=新字符串（buffer.array（））.trim（）；
System.out.println（“从客户处收到：+msg”）；