Flex和Java整合错误 [FaultEvent fault=[RPC Fault faultString="Send failed"

第一次按照例子做的FLEX DEMO  ,出现如下错误 ,在此记录一下:
    [FaultEvent fault=[RPC Fault faultString="Send failed"   
     faultCode="Client.Error.MessageSend"
     faultDetail="Channel.Connect.Failed error NetConnection.Call.Failed:
      HTTP: Status 404: url: 'http://localhost:8080/WebContent/messagebroker/amf'"]
    messageId="C25D6E12-4A22-9827-849A-C56BBBB434F4" type="fault" bubbles=false
    cancelable=true eventPhase=2]


解决方法:
在
<mx:RemoteObject id="firstRO" destination="FirstJavaClassRemoteObject"
fault="faultEvent(event)" endpoint="http://localhost:8080/FlexDemo/messagebroker/amf"/>