Cannot change version of project facet Dynamic Web Module to 3.0

参考:http://blog.sina.com.cn/s/blog_67e192090102v6u0.html

另外一个错：Description Resource Path Location Type Cannot change version of project facet Dynamic Web Module to 3.1.

解决：http://crunchify.com/how-to-solve-dynamic-web-module-3-1-requires-java-1-7-or-newer-in-eclipse/ （pom.xml配置解决了问题）