这是什么错??????????

CoreException: Could not get the value for parameter compilerId for plugin execution default-compile: PluginResolutionException: Plugin org.apache.maven.plugins:maven-compiler-plugin:2.5.1 or one of its dependencies could not be resolved: Failed to collect dependencies for org.apache.maven.plugins:maven-compiler-plugin:jar:2.5.1 (): ArtifactDescriptorException: Failed to read artifact descriptor for org.codehaus.plexus:plexus-compiler-api:jar:1.9.1: UnresolvableModelException: Failure to transfer org.codehaus.plexus:plexus-components:pom:1.1.20 from http://repo1.maven.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced. Original error: Could not transfer artifact org.codehaus.plexus:plexus-components:pom:1.1.20 from/to central (http://repo1.maven.org/maven2): The operation was cancelled.

用百度翻译,翻译一下在放上来