Cannot resolve plugin org.scala-tools:maven-scala-plugin: unknown

使用maven下载IDEA的 maven-scala-plugin 时报如下4个错误：

Cannot resolve plugin org.scala-tools:maven-scala-plugin:<unknown>

Could not find artifact org.scala-lang:scala-compiler:pom:2.11.12 in scala-tools.org (http://scala-tools.org/repo-releases)

Could not find artifact org.scala-tools:maven-scala-plugin:jar: in scala-tools.org (http://scala-tools.org/repo-releases)
Failure to find org.scala-lang:scala-library:pom:2.11.12 in http://scala-tools.org/repo-releases was cached in the local repository, resolution will not be reattempted until the update interval of scala-tools.org has elapsed or updates are forced

解决方法如下：

首先：IDEA插件自动生成的pom文件中scala的版本是2.7，这里需要修改成与本地scala一致的版本号，我的是2.11.12

然后将在pom文件中添加如下依赖：

    <dependency>
      <groupId>org.scala-tools</groupId>
      <artifactId>maven-scala-plugin</artifactId>
      <version>2.11</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-eclipse-plugin</artifactId>
      <version>2.5.1</version>
    </dependency>

最后：在pom文件中右键 Maven-->Reimport ;

如果还失败；IDEA右侧Maven框下：项目 --> Plugins --> clean --> clean:clean ;然后再Reimport。