算法之匹配：KMP

public static int getIndexOf(String str1, String str2) {
		if (str1 == null || str2 == null || str1.length() < str2.length()) {
			return -1;
		}
		char[] mm = str1.toCharArray();
		char[] nn = str2.toCharArray();
		int[] next = getNextArray(str2);
		int m = 0;
		int n = 0;
		while (m < mm.length && n < nn.length) {
			if (mm[m] == nn[n]) {
				m++;
				n++;
			} else if (n == 0) {
				m++;
			} else {
				n = next[n];
			}
		}
		return n == nn.length ? m-n : -1;

	}

	public static int[] getNextArray(String str) {
		if (str.length() == 1) {
			return new int[]{-1};
		}
		char[] str2 = str.toCharArray();
		int[] next = new int[str.length()];
		next[0] = -1;
		next[1] = 0;
		int i = 2;
		int flag = 0;
		while (i < str.length()) {
			if (str2[i - 1] == str2[flag]) {
				next[i] = flag + 1;
				i++;
				flag++;
			} else if (flag > 0) {
				flag = next[flag];
			} else {
				next[i] = 0;
				i++;
			}
		}
		return next;
	}