Failure to find org.eclipse.m2e:lifecycle-mapping:pom:1.0.0 in http://maven.aliyun.com/nexus/content

练习项目时，用generator maven自动生成代码时，控制台出现的错误

Failure to find org.eclipse.m2e:lifecycle-mapping:pom:1.0.0 in 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-aliyun has elapsed or updates are forced

先去码云下载dummy-lifecycle-mapping-plugin。放入一个位置，在使用generato的项目中点击File-->Open-->找到下载文件中的pom，然后会弹出一个框，选择以File的形式打开，之后在右击鼠标点击Open in Terminal在控制台输入mvn clean install。

再次启动，就生成成功对应的实体类和mapper文件