Demo启动总是报错怎么办？?报错

@JFinal 你好，想跟你请教个问题：

Demo启动总是报错怎么办？

Starting JFinal 2.0
Starting scanner at interval of 5 seconds.
Starting web server on port: 80
2015-12-26 11:26:25.384:WARN:oejuc.AbstractLifeCycle:FAILED jfinal: java.lang.IllegalArgumentException: Properties file not found in classpath: a_little_config.txt
java.lang.IllegalArgumentException: Properties file not found in classpath: a_little_config.txt
at com.jfinal.kit.Prop.<init>(Prop.java:60)
at com.jfinal.kit.PropKit.use(PropKit.java:65)
at com.jfinal.kit.PropKit.use(PropKit.java:39)
at com.jfinal.weixin.demo.WeixinConfig.loadProp(WeixinConfig.java:31)
at com.jfinal.weixin.demo.WeixinConfig.configConstant(WeixinConfig.java:36)
at com.jfinal.core.Config.configJFinal(Config.java:46)
at com.jfinal.core.JFinal.init(JFinal.java:65)
at com.jfinal.core.JFinalFilter.init(JFinalFilter.java:49)
at org.eclipse.jetty.servlet.FilterHolder.doStart(FilterHolder.java:119)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:724)
at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:265)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:706)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:492)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:95)
at org.eclipse.jetty.server.Server.doStart(Server.java:277)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at com.jfinal.server.JettyServer.doStart(JettyServer.java:121)
at com.jfinal.server.JettyServer.start(JettyServer.java:64)
at com.jfinal.core.JFinal.start(JFinal.java:137)

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a_little_config.txt 这个文件肯定是存在的，下载了Demo后修改了a_little_config.txt中的配置信息就没改动过。