java 正则表达式

package com.project.utils;

import org.apache.commons.lang.StringUtils;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class ContentUtils {
    public static void main(String[] args) {
        getPageId("https://www.cnblogs.com/alibai/p/topicId=123456789/topicId=12345678/topicId=1234567");
    }

    public static String getPageId(String url) {
        System.out.println(url);
        String pageId = "";
        if (StringUtils.isBlank(url)) {
            return pageId;
        }
        Pattern pattern = Pattern.compile("topicId=\d+");
        Matcher matcher = pattern.matcher(url);
        if (matcher.find()) {
            pageId = matcher.group().split("topicId")[1];
        }
        while (matcher.find()){
            System.out.println(matcher.group());
        }
        return pageId;
    }
}