NoClassDefFoundError: org/apache/commons/lang/StringUtils

[moonlightheng]

run GithubRepoPageProcessor
then print Exception as follows:

Exception in thread "pool-1-thread-1" java.lang.NoClassDefFoundError: org/apache/commons/lang/StringUtils
at us.codecraft.webmagic.downloader.HttpClientDownloader.getHtmlCharset(HttpClientDownloader.java:212)
at us.codecraft.webmagic.downloader.HttpClientDownloader.getContent(HttpClientDownloader.java:194)
at us.codecraft.webmagic.downloader.HttpClientDownloader.handleResponse(HttpClientDownloader.java:182)
at us.codecraft.webmagic.downloader.HttpClientDownloader.download(HttpClientDownloader.java:96)
at us.codecraft.webmagic.Spider.processRequest(Spider.java:409)
at us.codecraft.webmagic.Spider$1.run(Spider.java:322)
at us.codecraft.webmagic.thread.CountableThreadPool$1.run(CountableThreadPool.java:74)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang.StringUtils
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 10 more

I can not find org.apache.commons.lang.StringUtils in maven repository
why not use commons-lang3