code: public static int count(String regex, CharSequence content) {
  		if (null == regex || null == content) {
  			return 0;
  		}
  
  		// Pattern pattern = Pattern.compile(regex, Pattern.DOTALL);
  		final Pattern pattern = PatternPool.get(regex, Pattern.DOTALL);
  		return count(pattern, content);
  	}
docs: 计算指定字符串中，匹配pattern的个数
  
  @param regex 正则表达式
  @param content 被查找的内容
  @return 匹配个数