public class Test {   
public static void main(String[] args) {   
// TODO Auto-generated method stub   
String str = "111.3.22.11";   
str=str.replaceAll("(^|\\.)(\\d)(\\.|$)","$100$2$3");   
str=str.replaceAll("(^|\\.)(\\d{2})(\\.|$)","$10$2$3");   
str=str.replaceAll("(^|\\.)(\\d{2})(\\.|$)","$10$2$3");   
str=str.replaceAll("(^|\\.)(\\d{1})(\\.|$)","$100$2$3");   
           
System.out.println(str);   
}   
  
}  

str=str.replaceAll("(^|\\.)(\\d)(\\.|$)","$100$2$3");   这个语句中的正则表达式谁能解释下吗？

$100$2$3  这三个$分别表示撒

我知道到$1$2$3,分别表示前面元组匹配到的字符串。说明匹配到的字符串数据不变。中间加2个00