maven3 依赖的升级 （强制）
[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-0.20.2Caused 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 repository, resolution will not be reattempted until the update interval of public-repo has elapsed or updates are forcedTry 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）。
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原因是我之前用的是hadoop0.20.1 现在想换成 0.20.2 版本
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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。
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于是乎 执行 mvn eclipse:eclipse -U ?便下载了0.20.2 版本的jar。
