解决The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path
1、安装tomcat ，tomcat7.0版本以上无需配置环境变量。
2、报错
The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path
解决方法：右键项目——>Build Path——>Configure Build Path——>Build and Path——>Add Library
选择Server Runtinme，然后点击Next
如图选择Tomcat，前提是已在本机安装了tomcat，然后点击Finish。