axis 为什么调用两次header

Question

wsdd文件中这样子配置的：

<service   name = "AmwayMsgService"   provider = "java:RPC" >    
    <namespace>http://amway.com/amway/ebiz/webService/msgService/</namespace>  
    <parameter name="className"
        value="com.amway.ebiz.webService.msgService.AmwayMsgService" />
    <parameter name="allowedMethods" value="*" />           
    <beanMapping languageSpecificType="java:com.amway.ebiz.webService.msgService.Message" 
                  qname="ns11:Message"  xmlns:ns11="http://amway.com/amway/ebiz/webService/msgService"/>
     <beanMapping languageSpecificType="java:com.amway.ebiz.webService.msgService.MessageRequest" 
                  qname="ns12:MessageRequest"  xmlns:ns12="http://amway.com/amway/ebiz/webService/msgService"/>
     <beanMapping languageSpecificType="java:com.amway.ebiz.webService.msgService.MessageResponse" 
                  qname="ns13:MessageResponse"   xmlns:ns13="http://amway.com/amway/ebiz/webService/msgService"/>
     <requestFlow>  
       <chain type="checkHandler" />  
     </requestFlow>                                         
</service> 

但是头方法中却被调用了两次，头方法的代码如下：

public class MessageHeader extends BasicHandler {

private static final long serialVersionUID = 7284285169168827823L;

@Override
public void invoke(MessageContext context) throws AxisFault {
    System.out.println("进入了头方法");

}

}
打印了两次进入头方法，求大牛帮我看看 为什么，我用的axis1 。