maven尝试下载上次下载时没有的包

[ERROR] Failed to execute goal on project esf-common: Could not resolve dependencies for project com.sinohealth:esf-common:jar:1.0-SNAPSHOT: Failure to find bitwalker:UserAgentUtils:jar:1.13 in http://192.168.2.136:8081/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 -> [Help 1]

第一次编译时，自己架设的maven代理nexus中没有UserAgentUtils:jar这个包。后来在网上下载了这个包，并上传到代理后，再编译时，还报这个错，原因是缓中记录这个库中没有这个包。解决的办法是加-U参数，让maven重新尝试下载没有的包：

mvn clean install -U

更多命令参数，可以mvn -help查看