我已经学习了nutch（版本nutch-1.14）一周了，在本地模式和hadoop-2.7.2（伪分布式模式）下都工作得很好。今天我在nutch-site.xml中遇到了“take.screenshot”、“screenshot.location”属性，在修改这些属性之后，nutch正在爬行种子url，但是没有像hadoop那样在本地模式下截图。
本地模式的nutch-site.xml设置

<property>
 <name>take.screenshot</name>
 <value>true</value>
 <description>
  Boolean property determining whether the protocol-htmlunit
  WebDriver should capture a screenshot of the URL. If set to
  true remember to define the 'screenshot.location'
  property as this determines the location screenshots should be
  persisted to on HDFS. If that property is not set, screenshots
  are simply discarded.
 </description>
</property>

<property>
 <name>screenshot.location</name>
 <value>/home/user/nutch-1.14/screenshot</value>
 <description>
  The location on disk where a URL screenshot should be saved
  to if the 'take.screenshot' property is set to true.
  By default this is null, in this case screenshots held in memory
  are simply discarded.
 </description>
</property>

hadoop的nutch-site.xml设置

<property>
 <name>take.screenshot</name>
 <value>true</value>
</property>

<property>
 <name>screenshot.location</name>
 <value>/screenshot</value>
</property>

注意：hdfs中存在“screenshot”目录