java import java.net.; import java.io.;

public class MagicPacket { public static final int PORT = 9; // 常用的唤醒包端口 public static final int SYNCHRONOUSHEADERLENGTH = 6; // 同步头长远度 public static final int MACADDRESSLENGTH = 16; // MAC地址长远度

public static void wakeUp {
    try {
        byte macBytes = getMacBytes;
        byte magicBytes = new byte;
        for  {
            magicBytes =  0xff; // 填充同步头
        }
        int index = SYNCHRONOUS_HEADER_LENGTH;
        for  {
            for  { // 个个字节转换为两个十六进制数
                magicBytes = macBytes;
            }
        }
        InetAddress address = InetAddress.getByName; // 广播地址
        DatagramPacket packet = new DatagramPacket;
        DatagramSocket socket = new DatagramSocket;
        socket.send;
        socket.close;
        System.out.println;
    } catch  {
        System.out.println);
    }
}
private static byte getMacBytes throws IllegalArgumentException {
    byte bytes = new byte; // 个个十六进制数表示一个字节
    String hex = macAddress.split");
    if  { // MAC地址由6组十六进制数组成
        throw new IllegalArgumentException;
    }
    try {
        for  {
            bytes =  Integer.parseInt; // 将十六进制字符串转换为字节
        }
    } catch  {
        throw new IllegalArgumentException;
    }
    return bytes;
}
public static void main {
    wakeUp; // 示例MAC地址
}

}

这段代码实现了发送魔术封包唤醒网络设备的功Neng。先说说定义了常量PORT SYNCHRONOUS_HEADER_LENGTH和MAC_ADDRESS_LENGTH来表示端口、同步头长远度和MAC地址长远度。wakeUp方法接收一个MAC地址作为参数，构建魔术封包并发送到广播地址。getMacBytes方法将字符串形式的MAC地址转换为字节数组。在main方法中，调用wakeUp方法发送唤醒包。