net_io.utils.ByteUtils Maven / Gradle / Ivy
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package net_io.utils;
public class ByteUtils {
/** long型首字节二进制全1数 **/
private static final long MASK_LONG_1_BYTE = 0xFFL;
/** int型首字节二进制全1数 **/
private static final int MASK_INT_1_BYTE = 0xFF;
/**
* 生成随机字节数组
* @param length 字节数组的长度
* @return 非空随机字节数组
*/
public static byte[] generateRandomBytes(int length) {
byte[] result = new byte[length];
long timeHash = System.nanoTime();
timeHash ^= timeHash >>> 16;
timeHash ^= timeHash >>> 16;
int num = ((int) timeHash) & 0xFFFF;
for(int i=0; i 8) {
throw new IndexOutOfBoundsException("Can not parse long number. byteCount: " + byteCount);
}
if(data == null || offset < 0 || offset + byteCount > data.length) {
throw new IndexOutOfBoundsException("Can not parse long number. offset: " + offset);
}
long result = 0;
int k = (byteCount - 1) * 8;
while(k >= 0) {
long num = ((long) data[offset++]) & MASK_LONG_1_BYTE;
if(k > 0) {
result |= num << k;
} else {
result |= num;
}
k -= 8;
}
return result;
}
/**
* 从字节数组，按高字节在前的存储方式，解析一个 int 型数字
* 注意：若取数的位置，不在字节数组的范围内，抛出异常 IndexOutOfBoundsException
* @param data 字节数组
* @param offset 解析数据的偏移量
* @param byteCount 取字节数量（最小1，最大4）
* @return int型数字（允许负数）
*/
public static int parseIntAsBigEndian(byte[] data, int offset, int byteCount) {
if(byteCount <= 0 || byteCount > 4) {
throw new IndexOutOfBoundsException("Can not parse integer number. byteCount: " + byteCount);
}
if(data == null || offset < 0 || offset + byteCount > data.length) {
throw new IndexOutOfBoundsException("Can not parse integer number. offset: " + offset);
}
int result = 0;
int k = (byteCount - 1) * 8;
while(k >= 0) {
int num = ((int) data[offset++]) & MASK_INT_1_BYTE;
if(k > 0) {
result |= num << k;
} else {
result |= num;
}
k -= 8;
}
return result;
}
/**
* 从字节数组，按高字节在前的存储方式，解析一个 short 型数字
* 注意：若取数的位置，不在字节数组的范围内，抛出异常 IndexOutOfBoundsException
* @param data 字节数组
* @param offset 解析数据的偏移量
* @param byteCount 取字节数量（最小1，最大2）
* @return short型数字（允许负数）
*/
public static short parseShortAsBigEndian(byte[] data, int offset, int byteCount) {
if(byteCount <= 0 || byteCount > 2) {
throw new IndexOutOfBoundsException("Can not parse short number. byteCount: " + byteCount);
}
if(data == null || offset < 0 || offset + byteCount > data.length) {
throw new IndexOutOfBoundsException("Can not parse short number. offset: " + offset);
}
int result = ((int) data[offset]) & MASK_INT_1_BYTE;
if(byteCount > 1) {
result <<= 8;
result |= ((int) data[offset+1]) & MASK_INT_1_BYTE;
}
return (short)result;
}
/**
* 从字节数组，按高字节在前的存储方式，解析一个 long 型数字
* 注意：若取数的位置，不在字节数组的范围内，抛出异常 IndexOutOfBoundsException
* @param data 字节数组
* @param offset 解析数据的偏移量
* @param byteCount 取字节数量（最小1，最大8）
* @return 解析数据的偏移量
*/
public static int writeNumberAsBigEndian(long num, byte[] data, int offset, int byteCount) {
if(byteCount <= 0 || byteCount > 8) {
throw new IndexOutOfBoundsException("Can not write long number. byteCount: " + byteCount);
}
if(data == null || offset < 0 || offset + byteCount > data.length) {
throw new IndexOutOfBoundsException("Can not write long number. offset: " + offset);
}
int k = (byteCount - 1) * 8;
while(k >= 0) {
data[offset++] = (byte) ((num >>> k) & MASK_LONG_1_BYTE);
k -= 8;
}
return offset;
}
}