No plugin found for prefix 'tomcat7' in the current project and in the plugin groups

在maven web项目中加入了tomact插件，右侧maven run时报错：
No plugin found for prefix ‘tomcat7’ in the current project and in the plugin groups

解决办法1：

找到这个settings.xml文件,进行编辑,在pluginGroups标签下加入下面的配置

org.apache.tomcat.maven

解决方法二:在pom.xml文件中加入

    
        apache.snapshots
        Apache Snapshots
        http://repository.apache.org/content/groups/snapshots-group/
        
            false
        
        
            true
        
    

解决方法三:加入这个tomcat7配置

    org.apache.tomcat.maven
    tomcat7-maven-plugin
    2.2