我需要在Java代码中将2个字节(2的补码)转换为int。我该怎么做?
toInt(byte hb, byte lb) { }
答案 0 :(得分:15)
return ((int)hb << 8) | ((int)lb & 0xFF);
所有情况下的正确操作都留给学生练习。
答案 1 :(得分:10)
您还可以使用ByteBuffer类:
public int toInt(byte hb, byte lb) {
ByteBuffer bb = ByteBuffer.wrap(new byte[] {hb, lb});
return bb.getShort(); // Implicitly widened to an int per JVM spec.
}
如果要解码大量数据,此类可能会有所帮助。
答案 2 :(得分:1)
<强>用法:强>
public class Test {
public static void main(String[] args) {
byte[] b = new byte[] { -83, 0, 0, 0 };
int i = GattUtils.getIntValue(b, GattUtils.FORMAT_UINT32, 0);
System.out.println(i); //will print 173
}
public class GattUtils {
public static final long leastSigBits = 0x800000805f9b34fbL;
public static final int FIRST_BITMASK = 0x01;
public static final int SECOND_BITMASK = FIRST_BITMASK << 1;
public static final int THIRD_BITMASK = FIRST_BITMASK << 2;
public static final int FOURTH_BITMASK = FIRST_BITMASK << 3;
public static final int FIFTH_BITMASK = FIRST_BITMASK << 4;
public static final int SIXTH_BITMASK = FIRST_BITMASK << 5;
public static final int SEVENTH_BITMASK = FIRST_BITMASK << 6;
public static final int EIGTH_BITMASK = FIRST_BITMASK << 7;
public static final int FORMAT_UINT8 = 17;
public static final int FORMAT_UINT16 = 18;
public static final int FORMAT_UINT32 = 20;
public static final int FORMAT_SINT8 = 33;
public static final int FORMAT_SINT16 = 34;
public static final int FORMAT_SINT32 = 36;
public static final int FORMAT_SFLOAT = 50;
public static final int FORMAT_FLOAT = 52;
public static UUID toUuid(String uuidString) {
return UUID.fromString(uuidString);
}
public static UUID toUuid(long assignedNumber) {
return new UUID((assignedNumber << 32) | 0x1000, leastSigBits);
}
public static String toUuid128(long assignedNumber) {
return toUuid(assignedNumber).toString();
}
public static String toUuid16(int assignedNumber) {
return Integer.toHexString(assignedNumber);
}
public static Integer getIntValue(byte[] value, int format, int position) {
if (value == null)
return null;
if (position + (format & 0xF) > value.length)
return null;
switch (format) {
case FORMAT_UINT8:
return Integer.valueOf(value[position] & 0xFF);
case FORMAT_UINT16:
return Integer.valueOf(add(value[position], value[(position + 1)]));
case FORMAT_UINT32:
return Integer.valueOf(add(value[position], value[(position + 1)], value[(position + 2)], value[(position + 3)]));
case FORMAT_SINT8:
return Integer.valueOf(signed(value[position] & 0xFF, 8));
case FORMAT_SINT16:
return Integer.valueOf(signed(add(value[position], value[(position + 1)]), 16));
case FORMAT_SINT32:
return Integer.valueOf(signed(add(value[position], value[(position + 1)], value[(position + 2)], value[(position + 3)]), 32));
}
return null;
}
public static Float getFloatValue(byte[] value, int format, int position) {
if (value == null)
return null;
if (position + (format & 0xF) > value.length)
return null;
int i;
int mantissa;
int exponent;
switch (format) {
case FORMAT_SFLOAT:
i = value[(position + 1)];
position = value[position];
mantissa = signed((position & 0xFF) + ((i & 0xFF & 0xF) << 8), 12);
exponent = signed((i & 0xFF) >> 4, 4);
return Float.valueOf((float) (mantissa * Math.pow(10.0D, exponent)));
case FORMAT_FLOAT:
exponent = value[(position + 3)];
mantissa = value[(position + 2)];
i = value[(position + 1)];
position = value[position];
return Float.valueOf((float) ((format = signed((position & 0xFF) + ((i & 0xFF) << 8) + ((mantissa & 0xFF) << 16), 24)) * Math.pow(10.0D, exponent)));
}
return null;
}
public static String getStringValue(byte[] value, int position) {
if (value == null)
return null;
if (position > value.length)
return null;
byte[] arrayOfByte = new byte[value.length - position];
for (int i = 0; i != value.length - position; i++) {
arrayOfByte[i] = value[(position + i)];
}
return new String(arrayOfByte);
}
private static int add(byte byte1, byte byte2) {
return (byte1 & 0xFF) + ((byte2 & 0xFF) << 8);
}
private static int add(byte byte1, byte byte2, byte byte3, byte byte4) {
return (byte1 & 0xFF) + ((byte2 & 0xFF) << 8) + ((byte3 & 0xFF) << 16) + ((byte4 & 0xFF) << 24);
}
private static int signed(int value, int length) {
if ((value & 1 << length - 1) != 0)
value = -1 * ((1 << length - 1) - (value & (1 << length - 1) - 1));
return value;
}
/**
* Convert hex byte array from motorola API to byte array.
*
* @param hexByteArray
* @return
*/
public static byte[] hexByteArrayToByteArray(byte[] hexByteArray) {
return hexStringToByteArray(new String(hexByteArray));
}
/**
* Convert string from motorola API to a byte array.
*
* @param hexString
* @return
*/
public static byte[] hexStringToByteArray(String hexString) {
int len = hexString.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4) + Character.digit(hexString.charAt(i + 1), 16));
}
return data;
}
}
答案 3 :(得分:0)
public int toInt(byte hb, byte lb)
{
return ((int)hb)<<8 + lb;
}
答案 4 :(得分:0)
对于那些正在寻找Little Endian值的人:
int num = ByteBuffer.wrap(b, 0, 2).order(LITTLE_ENDIAN).char.toInt()