jetty 7启动时加上jetty.xml报错?报错

jetty 7启动时加上jetty.xml报错(java -jar start.jar etc/jetty.xml)：

2015-07-08 16:49:12.113:WARN:oejuc.AbstractLifeCycle:FAILED SelectChannelConnector@0.0.0.0:8081: java.net.BindException:
 Address already in use: bind
java.net.BindException: Address already in use: bind
        at sun.nio.ch.Net.bind0(Native Method)
        at sun.nio.ch.Net.bind(Unknown Source)
        at sun.nio.ch.Net.bind(Unknown Source)
        at sun.nio.ch.ServerSocketChannelImpl.bind(Unknown Source)
        at sun.nio.ch.ServerSocketAdaptor.bind(Unknown Source)
        at org.eclipse.jetty.server.nio.SelectChannelConnector.open(SelectChannelConnector.java:187)
        at org.eclipse.jetty.server.AbstractConnector.doStart(AbstractConnector.java:316)
        at org.eclipse.jetty.server.nio.SelectChannelConnector.doStart(SelectChannelConnector.java:265)
        at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
        at org.eclipse.jetty.server.Server.doStart(Server.java:292)
        at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
        at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1274)
        at java.security.AccessController.doPrivileged(Native Method)
        at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1197)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.eclipse.jetty.start.Main.invokeMain(Main.java:473)
        at org.eclipse.jetty.start.Main.start(Main.java:615)
        at org.eclipse.jetty.start.Main.main(Main.java:96)
2015-07-08 16:49:12.143:WARN:oejuc.AbstractLifeCycle:FAILED org.eclipse.jetty.server.Server@28e51e50: java.net.BindExcep
tion: Address already in use: bind
java.net.BindException: Address already in use: bind
        at sun.nio.ch.Net.bind0(Native Method)