replaceAll方法 替换 ip的地址解决思路

import java.util.regex.Matcher;import java.util.regex.Pattern;public class Test6 {    public static void main(String[] args) {        String str = "222.96.22.5";                // 方法 1（推荐）        Pattern pattern = Pattern.compile("(?<=^|\\.)(?:(\\d{2})|(\\d))(?!\\d)");        Matcher matcher = pattern.matcher(str);        StringBuffer sb = new StringBuffer();        while (matcher.find()) {            if (matcher.start(1) > 0) {                matcher.appendReplacement(sb, "0$1");            } else if (matcher.start(2) > 0) {                matcher.appendReplacement(sb, "00$2");            }        }        matcher.appendTail(sb);        System.out.println(sb.toString());                // 方法 2        str = str.replaceAll("(?<=^|\\.)(\\d{1,2})(?!\\d)", "0$1")                 .replaceAll("(?<=^|\\.)(\\d{2})(?!\\d)", "0$1");        System.out.println(str);    }}