异常Failure to transfer org.apache.maven.plugins:maven-surefire-plugin:pom:2.12.4 from http://maven.aliyun.com/nexus/content/groups/public was ...
错误异常：Failure to transfer org.apache.maven.plugins:maven-surefire-plugin:pom:2.12.4 from http://maven.aliyun.com/nexus/content/groups/public was cached in the local repository, resolution will not be reattempted until the update interval of nexus has elapsed or updates are forced. Original error: Could not transfer artifact org.apache.maven.plugins:maven-surefire-plugin:pom:2.12.4 from/to nexus (http://maven.aliyun.com/nexus/content/groups/public): maven.aliyun.com
（说明：今天早上打开eclipse后，就显出这个错误，pom.xml上面有个小红×，网上试了很多方法）
1.右击pom.xml->Run As->Maven Clean
pom.xml->Run As->Maven Install
(我用了，没效果，但是你可以先试试)
2.又尝试：在c盘用户里C:\Users\...\.m2\repository\org\apache\maven\plugins，
（别人的方法：）发现没有maven-surefire-plugin-2.**.*.jar这样的文件........(我发现我都不缺)，->project->maven->update...
3.我的解决方案
A.直接将C:\Users\...\.m2\repository\org\apache\maven\plugins\maven-surefire-plugin，整个文件夹删除
B.(Alt+F5)或者右击项目->Maven->Update project
