byte[] 转 int int 转byte apache mina源码

jinquan26

/**
* Returns the integer represented by up to 4 bytes in network byte order.
*
* @param buf the buffer to read the bytes from
* @param start
* @param count
* @return
*/
public static int networkByteOrderToInt(byte[] buf, int start, int count) {
if (count > 4) {
throw new IllegalArgumentException("Cannot handle more than 4 bytes");
}
int result = 0;
for (int i = 0; i < count; i++) {
result <<= 8;
result |= (buf[start + i] & 0xff);
}
return result;
}
/**
* Encodes an integer into up to 4 bytes in network byte order.
*
* @param num the int to convert to a byte array
* @param count the number of reserved bytes for the write operation
* @return the resulting byte array
*/
public static byte[] intToNetworkByteOrder(int num, int count) {
byte[] buf = new byte[count];
intToNetworkByteOrder(num, buf, 0, count);
return buf;
}
/**
* Encodes an integer into up to 4 bytes in network byte order in the
* supplied buffer starting at <code>start</code> offset and writing
* <code>count</code> bytes.
*
* @param num the int to convert to a byte array
* @param buf the buffer to write the bytes to
* @param start the offset from beginning for the write operation
* @param count the number of reserved bytes for the write operation
*/
public static void intToNetworkByteOrder(int num, byte[] buf, int start, int count) {
if (count > 4) {
throw new IllegalArgumentException("Cannot handle more than 4 bytes");
}
for (int i = count - 1; i >= 0; i--) {
buf[start + i] = (byte) (num & 0xff);
num >>>= 8;
}
}