将 32 位无符号整数(大端)转换为 long 并返回

2022-01-13 00:00:00 type-conversion unsigned-integer java endianness

我有一个 byte[4] 包含一个 32 位无符号整数(大端序)，我需要将它转换为 long(因为 int 不能保存无符号数).

I have a byte[4] which contains a 32-bit unsigned integer (in big endian order) and I need to convert it to long (as int can't hold an unsigned number).

另外，我该怎么做，反之亦然(即从包含 32 位无符号整数的 long 到 byte[4])?

Also, how do I do it vice-versa (i.e. from long that contains a 32-bit unsigned integer to byte[4])?

推荐答案

听起来像是 ByteBuffer.

有点像

public static void main(String[] args) {
    byte[] payload = toArray(-1991249);
    int number = fromArray(payload);
    System.out.println(number);
}

public static  int fromArray(byte[] payload){
    ByteBuffer buffer = ByteBuffer.wrap(payload);
    buffer.order(ByteOrder.BIG_ENDIAN);
    return buffer.getInt();
}

public static byte[] toArray(int value){
    ByteBuffer buffer = ByteBuffer.allocate(4);
    buffer.order(ByteOrder.BIG_ENDIAN);
    buffer.putInt(value);
    buffer.flip();
    return buffer.array();
}

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