我在Eclipse中运行的MacOS 10.11.5（El Capitan）上配置了一个本地Nutch 2.3.1实例，如下所述：https://wiki.apache.org/nutch/RunNutchInEclipse
作为要使用的数据存储，我配置了MongoDB 2.6.12，它也在我的本地MacOS机器上运行。我从这里获取了Gora配置：http://www.aossama.com/search-engine-with-apache-nutch-mongodb-and-elasticsearch/
的ivy.xml
<dependency org="org.apache.gora" name="gora-mongodb" rev="0.6.1" conf="*->default" />
gora.properties
gora.datastore.default=org.apache.gora.mongodb.store.MongoStore
gora.mongodb.override_hadoop_configuration=false
gora.mongodb.mapping.file=/gora-mongodb-mapping.xml
gora.mongodb.servers=localhost:27017
# I tried several server settings like localhost, 127.0.0.1, 127.0.0.1:27017, ...
gora.mongodb.db=nutch
我没有更改 gora-mongodb-mapping.xml 。
的nutch-site.xml中
<property>
<name>storage.data.store.class</name>
<value>org.apache.gora.mongodb.store.MongoStore</value>
<description>Default class for storing data</description>
</property>
如果我运行inject命令， hadoop.log 会显示这个令人困惑的结果：
2016-07-12 23:23:16,818 INFO crawl.InjectorJob - InjectorJob: starting at 2016-07-12 23:23:16
2016-07-12 23:23:16,819 INFO crawl.InjectorJob - InjectorJob: Injecting urlDir: /Users/myaccount/Documents/Nutch/urls
2016-07-12 23:23:17,054 WARN util.NativeCodeLoader - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2016-07-12 23:23:17,416 ERROR store.MongoStore -
2016-07-12 23:23:17,417 ERROR store.MongoStore - [Ljava.lang.StackTraceElement;@4b5189ac
2016-07-12 23:23:17,418 ERROR store.MongoStore - Error while initializing MongoDB store: java.lang.NullPointerException
2016-07-12 23:23:17,419 ERROR crawl.InjectorJob - InjectorJob: org.apache.gora.util.GoraException: java.lang.RuntimeException: java.io.IOException: java.lang.NullPointerException
at org.apache.gora.store.DataStoreFactory.createDataStore(DataStoreFactory.java:167)
at org.apache.gora.store.DataStoreFactory.createDataStore(DataStoreFactory.java:135)
at org.apache.nutch.storage.StorageUtils.createWebStore(StorageUtils.java:78)
at org.apache.nutch.crawl.InjectorJob.run(InjectorJob.java:233)
at org.apache.nutch.crawl.InjectorJob.inject(InjectorJob.java:267)
at org.apache.nutch.crawl.InjectorJob.run(InjectorJob.java:290)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.nutch.crawl.InjectorJob.main(InjectorJob.java:299)
Caused by: java.lang.RuntimeException: java.io.IOException: java.lang.NullPointerException
at org.apache.gora.mongodb.store.MongoStore.initialize(MongoStore.java:131)
at org.apache.gora.store.DataStoreFactory.initializeDataStore(DataStoreFactory.java:102)
at org.apache.gora.store.DataStoreFactory.createDataStore(DataStoreFactory.java:161)
... 7 more
Caused by: java.io.IOException: java.lang.NullPointerException
at org.apache.gora.mongodb.store.MongoMappingBuilder.fromFile(MongoMappingBuilder.java:123)
at org.apache.gora.mongodb.store.MongoStore.initialize(MongoStore.java:118)
... 9 more
Caused by: java.lang.NullPointerException
at org.apache.gora.mongodb.store.MongoMapping.newDocumentField(MongoMapping.java:109)
at org.apache.gora.mongodb.store.MongoMapping.addClassField(MongoMapping.java:169)
at org.apache.gora.mongodb.store.MongoMappingBuilder.loadPersistentClass(MongoMappingBuilder.java:169)
at org.apache.gora.mongodb.store.MongoMappingBuilder.fromFile(MongoMappingBuilder.java:112)
... 10 more
两天后我的想法用尽了。
在日志文件中，我无法识别任何有价值的提示。 MongoDB日志不显示任何连接尝试（更不用说活动连接）。使用mongo我能够连接到数据库并请求http://localhost:27017显示预期的消息（“看起来您正试图通过本机驱动程序端口上的HTTP访问MongoDB。” / em>）和相应的日志文件条目。如果我将数据存储切换到Cassandra，注入按预期工作，所以Nutch本身似乎也能工作。
有人知道我缺少什么或了解hadoop.log试图告诉我的内容吗？
任何帮助将不胜感激！ THX。
更新：我还尝试在Ubuntu 14.04服务器上使用此配置 - 按预期工作。所以我想我的问题与Nutch和amp;之间的联系有关。 MongoDB在Mac上运行。 （如果有人想知道：我正在尝试让我的Mac上的配置工作，因为我想做一些本地开发而不需要服务器连接。）