在Android 10中，/proc/net/arp文件已被移除，因此无法直接从中获取MAC地址。但是，您可以通过使用Java代码来获取设备的MAC地址。下面是一个示例代码，演示了如何从Socket /客户端PC获取MAC地址：

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;

public class MacAddressUtil {

    public static String getMacAddress(String ipAddress) {
        try {
            InetAddress inetAddress = InetAddress.getByName(ipAddress);
            NetworkInterface networkInterface = NetworkInterface.getByInetAddress(inetAddress);
            byte[] macAddressBytes = networkInterface.getHardwareAddress();
            
            StringBuilder macAddress = new StringBuilder();
            for (int i = 0; i < macAddressBytes.length; i++) {
                macAddress.append(String.format("%02X%s", macAddressBytes[i], (i < macAddressBytes.length - 1) ? ":" : ""));
            }
            
            return macAddress.toString();
            
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (SocketException e) {
            e.printStackTrace();
        }
        
        return null;
    }

    public static void main(String[] args) {
        String ipAddress = "192.168.0.100";  // Replace with the actual IP address of the client PC
        String macAddress = getMacAddress(ipAddress);
        
        System.out.println("MAC address of " + ipAddress + ": " + macAddress);
    }
}

在上述示例中，通过getMacAddress()方法传入客户端PC的IP地址，然后使用InetAddress类获取InetAddress对象，并使用NetworkInterface.getByInetAddress()方法获取NetworkInterface对象。最后，通过networkInterface.getHardwareAddress()方法获取设备的MAC地址的字节数组，并将其转换为十六进制格式的字符串。

请注意，您需要将示例代码中的ipAddress变量替换为实际的客户端PC的IP地址。