将整数转换为字节数组 （Java）

看看字节缓冲类。

ByteBuffer b = ByteBuffer.allocate(4);
//b.order(ByteOrder.BIG_ENDIAN); // optional, the initial order of a byte buffer is always BIG_ENDIAN.
b.putInt(0xAABBCCDD);

byte[] result = b.array();

设置字节顺序可确保 、 和 。result[0] == 0xAAresult[1] == 0xBBresult[2] == 0xCCresult[3] == 0xDD

或者，您可以手动执行此操作：

byte[] toBytes(int i)
{
  byte[] result = new byte[4];

  result[0] = (byte) (i >> 24);
  result[1] = (byte) (i >> 16);
  result[2] = (byte) (i >> 8);
  result[3] = (byte) (i /*>> 0*/);

  return result;
}

不过，该类是为这种肮脏的手任务而设计的。实际上，私有定义了这些帮助器方法，这些方法由 ：ByteBufferjava.nio.BitsByteBuffer.putInt()

private static byte int3(int x) { return (byte)(x >> 24); }
private static byte int2(int x) { return (byte)(x >> 16); }
private static byte int1(int x) { return (byte)(x >>  8); }
private static byte int0(int x) { return (byte)(x >>  0); }

用：BigInteger

private byte[] bigIntToByteArray( final int i ) {
    BigInteger bigInt = BigInteger.valueOf(i);      
    return bigInt.toByteArray();
}

用：DataOutputStream

private byte[] intToByteArray ( final int i ) throws IOException {      
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    DataOutputStream dos = new DataOutputStream(bos);
    dos.writeInt(i);
    dos.flush();
    return bos.toByteArray();
}

用：ByteBuffer

public byte[] intToBytes( final int i ) {
    ByteBuffer bb = ByteBuffer.allocate(4); 
    bb.putInt(i); 
    return bb.array();
}