com.acgist.snail.utils.NumberUtils Maven / Gradle / Ivy
package com.acgist.snail.utils;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Date;
import com.acgist.snail.system.exception.ArgumentException;
/**
* 数字工具
*
* @author acgist
* @since 1.0.0
*/
public class NumberUtils {
private static final int MIN_INT_INDEX = 1000;
private static final int MAX_INT_INDEX = 9999;
private static int index = MIN_INT_INDEX;
/**
* 生成唯一编号
* 长度：8
* 格式：index(4) + mmss
*/
public static final Integer build() {
final StringBuilder builder = new StringBuilder();
synchronized(NumberUtils.class) {
int index = NumberUtils.index;
builder.append(index);
if(++index > MAX_INT_INDEX) {
index = MIN_INT_INDEX;
}
NumberUtils.index = index;
}
builder.append(DateUtils.dateToString(new Date(), "mmss"));
return Integer.valueOf(builder.toString());
}
/**
* 除法，如果相除有余数，结果+1。
*/
public static final int divideUp(long dividend, long divisor) {
int value = (int) (dividend / divisor);
if(dividend % divisor != 0) {
value++;
}
return value;
}
/**
* 统计数字位上1的个数。
*/
public static final byte bitCount(int number) {
byte count = 0;
while (number != 0) {
number = number & (number - 1);
count++;
}
return count;
}
/**
* 无符号编码
*/
public static byte[] encodeUnsigned(BigInteger value, int byteCount) {
byte[] bytes = value.toByteArray();
if (bytes[0] == 0) {
bytes = Arrays.copyOfRange(bytes, 1, bytes.length);
}
if (bytes.length > byteCount) {
throw new ArgumentException("数组长度错误");
}
if (bytes.length < byteCount) {
final byte[] copy = bytes;
bytes = new byte[byteCount];
System.arraycopy(copy, 0, bytes, (bytes.length - copy.length), copy.length);
}
return bytes;
}
/**
* 无符号解码
*/
public static BigInteger decodeUnsigned(ByteBuffer buffer, int length) {
if (buffer.remaining() < length) {
throw new ArgumentException("数组长度错误");
}
byte b;
int index = 0;
while ((b = buffer.get()) == 0 && ++index < length) {
}
if (index == length) {
return BigInteger.ZERO;
}
int newLength = length - index;
final byte[] bytes = new byte[newLength];
bytes[0] = b;
buffer.get(bytes, 1, newLength - 1);
return new BigInteger(1, bytes);
}
}