Exception in thread "Spider-0" java.lang.NullPointerException - Gecco爬虫心得

使用Gecco爬虫时偶尔遇到如下莫名其妙的异常而停止：

Exception in thread "Spider-0" java.lang.NullPointerException
    at java.util.regex.Matcher.getTextLength(Matcher.java:1283)
    at java.util.regex.Matcher.reset(Matcher.java:309)
    at java.util.regex.Matcher.(Matcher.java:229)
    at java.util.regex.Pattern.matcher(Pattern.java:1093)
    at com.geccocrawler.gecco.utils.UrlMatcher.match(UrlMatcher.java:80)
    at com.geccocrawler.gecco.spider.SpiderBeanFactory.matchSpider(SpiderBeanFactory.java:112)
    at com.geccocrawler.gecco.spider.Spider.run(Spider.java:68)
    at java.lang.Thread.run(Thread.java:745)

后来细心查看才发现(SpiderBeanFactory.java:112)中，空指针调用的url地址是来自 request

于是做了如下测试：
HttpGetRequest start = new HttpGetRequest(null);
GeccoEngine.create()
        .classpath("com.example.crawler")
        .start(start)
        .interval(2000)
        .run();

由此可知，是爬虫过程中如下的调用没有保证url不为null

HttpRequest sub = l.getRequest().subRequest(url);
SchedulerContext.into(sub);

个人原创：爱我子月