Netty3 源码分析 - ChannelStateEvent

Netty3 源码分析 - ChannelStateEvent

ChannelStateEvent是ChannelEvent的子接口，可以代表改变的通知或者是请求，取决于它是上行还是下行事件。

UpstreamChannelStateEvent是默认的上行通道状态事件实现类。结合ChannelState中的表很容易看懂源码。

DownstreamChannelStateEvent 是默认的下行通道状态事件实现类。不同的是需要指定一个Future对象，当相应的动作完成后得到通知。源码很容易理解：

public   class  DownstreamChannelStateEvent  implements  ChannelStateEvent {

     private   final  Channel  channel ;

     private   final  ChannelFuture  future ;

     private   final  ChannelState  state ;

     private   final  Object  value ;

     //和UpstreamChannelStateEvent不同的是，多了一个Future对象，需要合适的时候得到通知

     public  DownstreamChannelStateEvent(

            Channel channel, ChannelFuture future,

            ChannelState state, Object value) {

         if  (channel ==  null ) {

             throw   new  NullPointerException(  "channel" );

        }

         if  (future ==  null ) {

             throw   new  NullPointerException(  "future" );

        }

         if  (state ==  null ) {

             throw   new  NullPointerException(  "state" );

        }

         this .  channel  = channel;

         this .  future  = future;

         this .  state  = state;

         this .  value  = value;

    }

     public  Channel getChannel() {

         return   channel ;

    }

     public  ChannelFuture getFuture() {

         return   future ;

    }

     public  ChannelState getState() {

         return   state ;

    }

     public  Object getValue() {

         return   value ;

    }

     @Override

     public  String toString() {

        String channelString = getChannel().toString();

        StringBuilder buf =  new  StringBuilder(channelString.length() + 64);

        buf.append(channelString);

         switch  (getState()) {

         case   OPEN :

             if  (Boolean.  TRUE .equals(getValue())) {

                buf.append(  " OPEN" );

            }  else  {

                buf.append(  " CLOSE" );

            }

             break ;

         case   BOUND :

             if  (getValue() !=  null ) {

                buf.append(  " BIND: " );

                buf.append(getValue());

            }  else  {

                buf.append(  " UNBIND" );

            }

             break ;

         case   CONNECTED :

             if  (getValue() !=  null ) {

                buf.append(  " CONNECT: " );

                buf.append(getValue());

            }  else  {

                buf.append(  " DISCONNECT" );

            }

             break ;

         case   INTEREST_OPS :

            buf.append(  " CHANGE_INTEREST: "  );

            buf.append(getValue());

             break ;

         default :

            buf.append(  ' ' );

            buf.append(getState().name());

            buf.append(  ": " );

            buf.append(getValue());

        }

         return  buf.toString();

    }

}