得到自然数因子

	public static boolean IsPrime(long number) {
		int begin = 2;
		int end = (int) Math.sqrt(number) + 1;
		for (int i = begin; i < end; i++) {
			if (number % i == 0)
				return false;
			for_count1++;
		}
		return true;
	}

	// 得到因子
	public static Set<Long> getFactor(Long number) {
		Set<Long> factors = new HashSet<Long>();
		Long begin = 2L;
		Long end = number;
		for (Long i = begin; i < end&&number!=1; i++) {
			if (number % i == 0) {
				factors.add(i);
				while ((number % i) == 0) {
					number = number / i;
					for_count1++;
				}
			}
			for_count1++;
		}
		if (number != 1) {
			factors.add(number);
		}
		return factors;
	}

	public static Set<Integer> getFactor1(Long number) {
		Set<Integer> factors = new HashSet<Integer>();
		if (number % 2 == 0) {
			factors.add(2);
			do {
				number = number / 2;
				for_count2++;
			} while (number % 2 == 0);
		}
		int i = 3;
		do {
			if (number % i == 0) {
				factors.add(i);
				do {
					number = number / i;
					for_count2++;
				}while (number % i == 0);
			}
			i = i + 2;
			for_count2++;
		} while (number != 1);

		return factors;
	}

	public static Set<Long> getFactor2(Long number) {
		Set<Long> factors = new HashSet<Long>();
		if (number % 2 == 0) {
			factors.add(2L);
			do {
				number = number / 2;
				for_count3++;
			} while (number % 2 == 0);
		}
		Long i = 3L;
		long maxFactor = (long)Math.sqrt(number);
		do {
			while (number % i == 0) {
				factors.add(i);
				number = number / i;
				for_count3++;
			}
			i = i + 2;
			for_count3++;
		} while (number != 1&&i<maxFactor);
		if(number!=1){
			factors.add(number);
		}

		return factors;
	}

运算结果：
2018的因子
[2, 1009] for_count1:1010
[2, 1009] for_count2:506
[2, 1009] for_count3:15
600851475143的因子
[6857, 71, 839, 1471] for_count1:6860
[6857, 71, 839, 1471] for_count2:3432
[6857, 71, 839, 1471] for_count3:3432