Maven错误：was cached in the local repository, resolution will not be reattempted until the update

问题及原因

今天在测试使用Spring BOM的时候，总发现项目无法打包成功。查看Maven的错误日志发现：

Non-resolvable import POM: Failure to find org.springframework:spring‐framework‐bom:pom:4.3.5.RELEASE in http://repo.spring.io/release/ was cached in the local repository, resolution will not be reattempted until the update interval of io.spring.repo.maven.release has elapsed or updates are forced @ line 29, column 19 -> [Help 2]

随即在StackOverFlow上查看了问题，发现主要是因为Maven默认会使用本地缓存的库来编译工程，而上次下载的库失败导致的。

解决办法

1. 删除~/.m2/repository/对应目录或目录下的*.lastUpdated文件，然后再次运行maven命令
2. maven命令后加-U，如mvn package -U
3. 在repository的release或者snapshots版本中新增updatePolicy属性，其中updatePolicy可以设置为”always”、”daily” (默认)、”interval:XXX” (分钟)或”never”

<repositories>
    <repository>
      <id>io.spring.repo.maven.release</id>
      <url>http://repo.spring.io/release/</url>
      <releases>
        <enabled>true</enabled>
        <updatePolicy>always</updatePolicy>
      </releases>
      <snapshots><enabled>false</enabled></snapshots>
    </repository>
  </repositories>

参考资源

1. http://stackoverflow.com/questions/4856307/when-maven-says-resolution-will-not-be-reattempted-until-the-update-interval-of/41391500#41391500
2. http://maven.apache.org/ref/3.3.9/maven-settings/settings.html