1.到工程目录下修改配置文件
project/.settings/org.eclipse.wst.common.project.facet.core.xml
project/.settings/org.eclipse.wst.common.project.facet.core.xml
<?xml version="1.0" encoding="UTF-8"?>
<faceted-project>
<fixed facet="wst.jsdt.web"/>
<installed facet="jst.web" version="2.5"/> 改成2.5
<installed facet="wst.jsdt.web" version="1.0"/>
<installed facet="java" version="1.7"/> 改成1.7
</faceted-project>