当我输入“grang appengineRun＆＃39;”时会发生错误。该命令挂起85％。当我访问localhost：8080时，它返回错误503.以下是命令的输出：
~/Code/gradle-google-cloud-engine-hello$ gradle appengineRun:compileJava NO-SOURCE
:processResources NO-SOURCE
:classes UP-TO-DATE
:war UP-TO-DATE
:explodeWar UP-TO-DATE
:assemble UP-TO-DATE
:appengineRun
2017-11-26 23:44:15.912:INFO::main: Logging initialized @303ms
2017-11-26 23:44:16.202:INFO:oejs.Server:main: jetty-9.3.18.v20170406
2017-11-26 23:44:16.303:INFO:oeja.AnnotationConfiguration:main: Scanning elapsed time=0ms
2017-11-26 23:44:16.446:WARN:oejs.BaseHolder:main:
java.lang.ClassNotFoundException: mysite.server.ComingSoonServlet
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:196)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.eclipse.jetty.util.Loader.loadClass(Loader.java:86)
at org.eclipse.jetty.servlet.BaseHolder.doStart(BaseHolder.java:95)
at org.eclipse.jetty.servlet.ServletHolder.doStart(ServletHolder.java:363)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:891)
at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:349)
at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1406)
lyArgs(Parser.java:47)
at com.google.appengine.tools.development.DevAppServerMain.run(DevAppServerMain.java:223)
at com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:214)
Nov 27, 2017 4:44:16 AM com.google.appengine.tools.development.ApiProxyLocalImpl log
SEVERE: javax.servlet.ServletContext log: unavailable
javax.servlet.UnavailableException: Class loading error for holder comingsoon@70f7c77c==mysite.server.ComingSoonServlet,jsp=null,order=-1,inst=false
'''skip'''com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:214)
2017-11-26 23:44:16.542:INFO:oejs.AbstractConnector:main: Started NetworkTrafficSelectChannelConnector@32ee6fee{HTTP/1.1,[http/1.1]}{localhost:8080}
2017-11-26 23:44:16.543:INFO:oejs.Server:main: Started @935ms
Nov 27, 2017 4:44:16 AM com.google.appengine.tools.development.AbstractModule startup
INFO: Module instance default is running at http://localhost:8080/
Nov 27, 2017 4:44:16 AM com.google.appengine.tools.development.AbstractModule startup
INFO: The admin console is running at http://localhost:8080/_ah/admin
Nov 26, 2017 11:44:16 PM com.google.appengine.tools.development.DevAppServerImpl doStart
INFO: Dev App Server is now running
> Building 85% > :appengineRun