今天在使用jetty做容器运行一个java web app时却给出了这样的错误：
java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "getClassLoader")
at java.security.AccessControlContext.checkPermission(Unknown Source)
at java.security.AccessController.checkPermission(Unknown Source)
at org.eclipse.jetty.server.handler.ContextHandler$Context.getClassLoader(ContextHandler.java:2390)
at org.apache.tomcat.util.scan.StandardJarScanner.scan(StandardJarScanner.java:210)
at org.apache.jasper.servlet.TldScanner.scanJars(TldScanner.java:250)
at org.apache.jasper.servlet.TldScanner.scan(TldScanner.java:106)
at org.apache.jasper.servlet.JasperInitializer.onStartup(JasperInitializer.java:103)
at org.eclipse.jetty.plus.annotation.ContainerInitializer.callStartup(ContainerInitializer.java:106)
at org.eclipse.jetty.annotations.ServletContainerInitializerListener.doStart(ServletContainerInitializerListener.java:107)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at org.eclipse.jetty.util.component.AggregateLifeCycle.doStart(AggregateLifeCycle.java:81)
at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:58)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:96)
at org.eclipse.jetty.server.handler.ScopedHandler.doStart(ScopedHandler.java:115)
at org.eclipse.jetty.server.handler.ContextHandler.startContext(ContextHandler.java:763)
at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:249)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1242)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:717)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:494)
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:282)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at net.sourceforge.eclipsejetty.starter.embedded.JettyEmbeddedAdapter.start(JettyEmbeddedAdapter.java:67)
at net.sourceforge.eclipsejetty.starter.common.AbstractJettyLauncherMain.launch(AbstractJettyLauncherMain.java:85)
at net.sourceforge.eclipsejetty.starter.embedded.JettyEmbeddedLauncherMain.main(JettyEmbeddedLauncherMain.java:42)
在网上搜索一番后，找到了解决办法：
1. 查看工程使用的哪个JRE
2. 在这个目录下的【security】文件夹下找到【java.policy】文件：
3. 用记事本或者notepad++打开它，并在grant中增加下面的两行，并保存。
4. 重启Jetty，错误消失，结果正常。
至于为什么这样可以解决，网上还搜到相关说明。我暂时也没时间去深究，等以后有时间再说吧。
