java - 从 Java 字节中提取半字节

Question

Hex:[0A][52][08][01][01][01][00][CD][21][02][59]


0      [0A]
1      [52]         Packettype    = TEMP_HUM
2      [08]         subtype       = TH8 - 
3      [01]         Sequence nbr  = 1
4/5    [01][01]     ID            = 257
6/7    [00][CD]     Temperature   = 20.5 °C
8      [21]         Humidity      = 33
9      [02]         Status        = Dry
10     [5] *nibble           Signal level  = 5
11     [9] *nibble           Battery       = OK

所以我通过串行端口获得了 11 个字节(十六进制)。 我将所有字节分配给一个字节数组，以便以后使用它们。

我有两个问题:

1] 如何在 Java 中将 4 和 5 个字节重新组合在一起(我假设是 INT)？ 2] 如何提取 10 和 11 或者最后一个字节的高半字节和低半字节？

[来自以下评论] 示例字节:高[0101][0110]低 lowNibble = yourbyte & 0x0f; 01010110 & 0x0f (00001111) = 00000110

           highNibble = yourByte >>>> 4
           01010110 >>> 4 = 00000101


          IF you use this Example Byte: High[1101][0110]Low
          highNibble = yourByte >>> 4
          11010110 >>> 4 = 00000101
          Because >>> removes the signed bit.

Answer 1

1) 这取决于字节顺序。它将是 (b[4] << 8) | b[5]或 (b[5] << 8) | b[4]

2) lowNibble = yourByte & 0x0f; highNibble = (yourByte >> 4) & 0x0f;

你也可以这样做:lowNibble = yourByte & 0x0f; highNibble = yourByte >>> 4;

无符号移位 ( >>> ) 用零填充高位，无论符号如何。