正则表达式中的groupCount与group

groupCount是用在pattern中有‘()’时使用
如pattern = "(src)='(http)://[^']+'";
找到的m.groupCount 就为2

m.group() = m.group(0) 是匹配的一整段
m.group(1) = src
m.group(2) = http

group的用法如下

public static void main(String[] args) {
		String src = "sss#this#xx#that#df";
		Pattern pattern = Pattern.compile("#\\w+#");
		Matcher matcher = pattern.matcher(src);
		System.out.println("matcher.groupCount():" + matcher.groupCount());
		while(matcher.find()){
			System.out.println(matcher.group()); 
		}
	}

输出为：

matcher.groupCount():0
#this#
#that#

如果pattern改为 Pattern.compile("#(\\w+)#");
则matcher.groupCount()输出为1