[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時出現了以上異常（前提我剛把maven2.2 升級成maven3）。
原因是我之前用的是hadoop0.20.1 現在想換成 0.20.2 版本
細讀了下worning 信息，發現maven3 必須強制 -U 來強制jar 升級 否則會喫先這樣的警告。
於是乎 執行 mvn eclipse:eclipse -U 便下載了0.20.2 版本的jar。