. 使用TCP协议编写一个网络程序，设置服务器端的监听端口是8002，当与客户端建立连接后，服务器端向客户端发送数据“Hello, world”，客户端收到数据后打印输出。

package TCP;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;


public class TCPREC {


   
    public static void main(String[] args) throws UnknownHostException, IOException {
        // TODO Auto-generated method stub
        new TCPClient().connect();
    }


}


class TCPClient{
    private static final int PORT = 8002;
    public void connect() throws UnknownHostException, IOException{
        Socket client = new Socket(InetAddress.getLocalHost(), PORT);
        InputStream is = client.getInputStream();
        byte[] buf = new byte[1024];
        int len = is.read(buf);
        System.out.println(new String(buf, 0, len));
        client.close();
    }

}

package TCP;


import java.io.IOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;




public class TCPSEND{


    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        new TCPServer().listen();
    }


}


class TCPServer{
    private static final int PORT = 8002;
    public void listen() throws IOException{
        ServerSocket serverSocket = new ServerSocket(PORT);
        Socket client = serverSocket.accept();
        OutputStream os = client.getOutputStream();
        System.out.println("开始与客户端交互数据");
        String str = "Hello,world";
        os.write(str.getBytes());
        System.out.println("结束与客户端交互数据");
        os.close();
        client.close();
    }
}