参见：https://blog.csdn.net/zxs9999/article/details/113511447 有常见的错误解决方法
https://www.cnblogs.com/wfdespace/p/12869277.html
https://www.cnblogs.com/H-BolinBlog/p/9047561.html 打包成war
https://blog.csdn.net/yangsnow_rain_wind/article/details/79551157 gradle编译成war放到tomcat中运行