[WARNING] Missing POM for org.apache.mahout.hadoop:hadoop-core:jar:0.20.2
[WARNING] An error occurred during dependency resolution.
Failed to retrieve org.apache.mahout.hadoop:hadoop-core-0.20.2
Caused by: Failure to find org.apache.mahout.hadoop:hadoop-core:jar:0.20.2 in http://localhost:8080/nexus/content/groups/public/ was cached in the local reposit
ory, resolution will not be reattempted until the update interval of public-repo has elapsed or updates are forced
Try downloading the file manually from the project website.
我在用hadoop时出现了以上异常（前提我刚把maven2.2 升级成maven3）。
原因是我之前用的是hadoop0.20.1 现在想换成 0.20.2 版本
细读了下worning 信息，发现maven3 必须强制 -U 来强制jar 升级 否则会吃先这样的警告。
于是乎 执行 mvn eclipse:eclipse -U 便下载了0.20.2 版本的jar。