如何在Java中检测URL末尾分页ID是否存在并获取其值

给定一批URL，部分末尾带有整数形式的分页ID，部分没有。需要实现逻辑判断URL末尾是否存在这类分页ID，存在则提取对应的数值。测试用的示例URL如下：

• localhost:8200/videos
• localhost:8200/videos/1
• localhost:8200/videos/2
• localhost:8200/videos/popular-entertainment
• localhost:8200/videos/popular-entertainment/1
• localhost:8200/videos/popular-entertainment/2
• localhost:8200/videos-funny/popular-entertainment
• localhost:8200/videos-funny/popular-entertainment/1
• localhost:8200/videos-funny/popular-entertainment/2
• localhost:8200/videos-funny/popular-entertainment/3

下面提供两种可靠的实现方法：

方法一：正则表达式匹配 #

直接用正则定位URL末尾的整数部分，代码简洁高效。

实现代码 #

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

public class PageIdExtractor {
    // 匹配末尾的/加数字
    private static final Pattern PAGE_PATTERN = Pattern.compile("/(\\d+)$");

    public static Integer getPageId(String url) {
        if (url == null || url.isBlank()) {
            return null;
        }
        Matcher matcher = PAGE_PATTERN.matcher(url);
        if (matcher.find()) {
            // 正则已经确保是数字，转Integer不会出错
            return Integer.parseInt(matcher.group(1));
        }
        return null;
    }

    // 测试用例
    public static void main(String[] args) {
        String[] testUrls = {
            "localhost:8200/videos",
            "localhost:8200/videos/1",
            "localhost:8200/videos/2",
            "localhost:8200/videos/popular-entertainment",
            "localhost:8200/videos/popular-entertainment/1",
            "localhost:8200/videos/popular-entertainment/2",
            "localhost:8200/videos-funny/popular-entertainment",
            "localhost:8200/videos-funny/popular-entertainment/1",
            "localhost:8200/videos-funny/popular-entertainment/2",
            "localhost:8200/videos-funny/popular-entertainment/3"
        };

        for (String url : testUrls) {
            Integer pageId = getPageId(url);
            System.out.printf("URL: %s → 分页ID: %s%n", url, pageId != null ? pageId : "不存在");
        }
    }
}

逻辑说明 #

• 正则/(\\d+)$专门匹配URL结尾的/+数字组合，$保证是字符串最后一段，避免误匹配路径中间的数字。
• 匹配到后直接提取捕获组里的数字字符串，转成Integer返回；没匹配到就返回null，表示没有分页ID。

方法二：拆分路径后校验最后一段 #

如果对正则不太熟悉，可以拆分URL路径，取最后一段判断是否为整数，逻辑更直观。

实现代码 #

public class PageIdExtractor {
    public static Integer getPageId(String url) {
        if (url == null || url.isBlank()) {
            return null;
        }
        // 先去掉查询参数（如果有）
        String path = url.split("\\?")[0];
        // 按/拆分路径
        String[] pathSegments = path.split("/");
        String lastSegment = pathSegments[pathSegments.length - 1];
        
        // 处理URL末尾带/的情况，比如"localhost:8200/videos/"
        if (lastSegment.isEmpty() && pathSegments.length > 1) {
            lastSegment = pathSegments[pathSegments.length - 2];
        }
        
        try {
            return Integer.parseInt(lastSegment);
        } catch (NumberFormatException e) {
            // 最后一段不是整数，返回null
            return null;
        }
    }

    // 测试用例
    public static void main(String[] args) {
        String[] testUrls = {
            "localhost:8200/videos",
            "localhost:8200/videos/1",
            "localhost:8200/videos/2",
            "localhost:8200/videos/popular-entertainment",
            "localhost:8200/videos/popular-entertainment/1",
            "localhost:8200/videos/popular-entertainment/2",
            "localhost:8200/videos-funny/popular-entertainment",
            "localhost:8200/videos-funny/popular-entertainment/1",
            "localhost:8200/videos-funny/popular-entertainment/2",
            "localhost:8200/videos-funny/popular-entertainment/3",
            "localhost:8200/videos/" // 测试末尾带/的场景
        };

        for (String url : testUrls) {
            Integer pageId = getPageId(url);
            System.out.printf("URL: %s → 分页ID: %s%n", url, pageId != null ? pageId : "不存在");
        }
    }
}

逻辑说明 #

1. 先剥离URL的查询参数部分，只保留路径。
2. 用/把路径拆分成数组，取最后一段；如果最后一段是空（URL末尾带/），就取倒数第二段。
3. 尝试把该段转成Integer，成功就返回数值，失败则说明不是分页ID，返回null。

内容的提问来源于stack exchange，提问作者Adarsh Awasthi