Project facet Java 1.8 is not supported by target runtime Apache Tomcat v7.0.

找到项目下的“.settings”

打开“org.eclipse.wst.common.project.facet.core.xml”文件

删除掉“<runtime name="Apache Tomcat v7.0"/>”

原文：http://www.cnblogs.com/liaojie970/p/5117549.html