java - 将 Short 转换为 3 字节数组

Question

我需要通过 UDP 传输号码。协议(protocol)指定数字为 3 个字节。

例如，我需要将 ID: 258 转换为字节数组:

byte[] a = new byte[3]

Answer 1

我认为它应该有效:

小端:

byte[] convertTo3ByteArray(short s){

   byte[] ret = new byte[3];
   ret[2] = (byte)(s & 0xff);
   ret[1] = (byte)((s >> 8) & 0xff);
   ret[0] = (byte)(0x00);

   return ret;

}

short convertToShort(byte[] arr){

    if(arr.length<2){
        throw new IllegalArgumentException("The length of the byte array is less than 2!");
    }

    return (short) ((arr[arr.length-1] & 0xff) + ((arr[arr.length-2] & 0xff ) << 8));       
}

大端:

byte[] convertTo3ByteArray(short s){

   byte[] ret = new byte[3];
   ret[0] = (byte)(s & 0xff);
   ret[1] = (byte)((s >> 8) & 0xff);
   ret[2] = (byte)(0x00);

   return ret;

}

short convertToShort(byte[] arr){

    if(arr.length<2){
        throw new IllegalArgumentException("The length of the byte array is less than 2!");
    }

    return (short) ((arr[0] & 0xff) + ((arr[1] & 0xff ) << 8));

}