1. 字符串.分隔
分隔符得是 regex， "."是转义字符，所以要加\
https://blog.csdn.net/kunlong0909/article/details/8507290
//JAVA API
public String[] split(String regex) {
return split(regex, 0);
}
//正确用法
String[] slist = fullMetricName.split("\\.");
//错误用法
String[] slist = fullMetricName.split(".");
