这是代码:
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Map;
public class Shiftcodes {
private Map<byte[], Byte> shiftMap;
public byte genoByte(byte b1, byte b2, byte b3, byte b4) {
return (byte) (
(b1 << 6)
| (b2 << 4)
| (b3 << 2)
| b4);
}
public static void main(String[] args) throws IOException {
Shiftcodes shiftcodes = new Shiftcodes();
byte b = shiftcodes.genoByte((byte) 0x01, (byte) 0x11, (byte) 0x00, (byte) 0x10);
FileOutputStream fileOutputStream = new FileOutputStream("/tmp/x.bin");
fileOutputStream.write(new byte[] {b});
}
}
假定每个字节的位都为零,除了最右边的两位(可以为0或1)之外,因此我对代码进行了一些更改:
public class Shiftcodes {
private Map<byte[], Byte> shiftMap;
public byte genoByte(byte b1, byte b2, byte b3, byte b4) {
return (byte) (
((b1 & 0x11) << 6)
| ((b2 & 0x11) << 4)
| ((b3 & 0x11) << 2)
| b4);
}
public static void main(String[] args) throws IOException {
Shiftcodes shiftcodes = new Shiftcodes();
byte b = shiftcodes.genoByte((byte) 0x01, (byte) 0x11, (byte) 0x00, (byte) 0x10);
FileOutputStream fileOutputStream = new FileOutputStream("/tmp/x.bin");
fileOutputStream.write(new byte[] {b});
}
}
但是在两种情况下,我都达到了我的期望(01110010):
xxd -b x.bin
0000000: 01010000 P
为什么?
最佳答案
您将hex literals
误认为binary literals
:
0x11; // Hex 11, Dec 17, Bits 00010001
0b11; // Hex 3, Dec 3, Bits 00000011
关于java - 用Java将4个字节合并为1个字节,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/30818930/