其实之前就遇到一次这样问题，但还是因记性，，所以开始记录自己的Error。
**出现问题：**Application Server was not connected before run configuration stop, reason: Unable to ping server at localhost:1099
Output：
“G:\Program Files (x86)\JetBrains\apache-tomcat-9.0.0.M17\bin\catalina.bat” run
[2017-03-13 09:47:13,693] Artifact WebApp:war exploded: Server is not connected. Deploy is not available.
The JRE_HOME environment variable is not defined correctly
This environment variable is needed to run this program
Disconnected from server
问题出现及解决过程：
1.刚开始学jsp，出现下图这种问题，
因安装的jdk没 servlet-api.jar,servlet.jar
就把工程jdk改成idea自带的了
之后便出现上述问题……..
之后就试着把jdk改回，成功了，，但是还会提示cannot resolve method，
最后把idea的jar都包含进来了，完成。
