Target runtime Apache Tomcat v7.0 is not defined.解决方法
在项目的根目录下找到.settings文件夹打开，找到org.eclipse.wst.common.project.facet.core.xml文件进行编辑.
1 <?xml version="1.0" encoding="UTF-8"?> 2 <faceted-project> 3 <runtime name="Apache Tomcat v8.0"/> 4 <fixed facet="java"/> 5 <fixed facet="wst.jsdt.web"/> 6 <fixed facet="jst.web"/> 7 <installed facet="jst.web" version="3.0"/> 8 <installed facet="wst.jsdt.web" version="1.0"/> 9 <installed facet="java" version="1.7"/> 10 </faceted-project>