Session是Apache的核心,每当一个客户端连接到达时,就会有一个新的Session被创建,直到该连接关闭。Session被用来保存连接,以及各种信息。
Session有如下几种状态:
Connected : the session has been created and is available Idle : the session hasn't processed any request for at least a period of time (this period is configurable) Idle for read : no read has actually been made for a period of time Idle for write : no write has actually been made for a period of time Idle for both : no read nor write for a period of time Closing : the session is being closed (the remaining messages are being flushed, cleaning up is not terminated) Closed : The session is now closed, nothing else can be done to revive it.
下图表示Session的状态转换关系:
以下几个参数可以用来配置Session
receive buffer size
sending buffer size
Idle time
Write timeOut
管理用户自定义的属性:
例如,如果你想跟踪一个用户从会话被建立之后发送了多少个请求,那么它可以很容易存入这种映射:只要创建一个key关联到value就行。
... int counterValue = session.getAttribute( "counter" ); session.setAttribute( "counter", counterValue + 1 ); ...
我们采用key/value 对的方式存储属性到会话中,这种key/value对可以通过session的容器读取,添加或删除。
定义container
正如我们所说,这个容器是一个key/value容器,默认是一种映射,当然也可以定义成其他的数据结构。当Session被创建时我们可以实现一个接口和一个factory用来创建容器。下面的代码片段示例了在Session初始化时如何创建容器(看不懂,这个到底什么意思?)
protected final void initSession(IoSession session, IoFuture future, IoSessionInitializer sessionInitializer) { ... try { ((AbstractIoSession) session).setAttributeMap(session.getService() .getSessionDataStructureFactory().getAttributeMap(session)); } catch (IoSessionInitializationException e) { throw e; } catch (Exception e) { throw new IoSessionInitializationException( "Failed to initialize an attributeMap.", e); }
and here is the factory interface we can implement if we want to define another kind of container :
public interface IoSessionDataStructureFactory { /** * Returns an {@link IoSessionAttributeMap} which is going to be associated * with the specified <tt>session</tt>. Please note that the returned * implementation must be thread-safe. */ IoSessionAttributeMap getAttributeMap(IoSession session) throws Exception; }
过滤链
每个会话会关联一些过滤链,用来处理到来的请求或者出去的数据。每个会话都会指定单独的过滤链,大多数情况下,我们会用在会话中用很多相同的过滤链。
统计
Each session also keep a track of records about what has been done for the session : number of bytes received/sent number of messages received/sent Idle status throughput and many other useful informations. Handler
最后,同样重要的是,一个Handler要附着于一个Session上,用来处理程序的消息。这个Handler也会发送包作为回应,只要简单的调用write方法即可:
... session.write( <your message> ); ...
以上就是Apache Mina 学习笔记(4)-Session的内容,更多相关内容请关注PHP中文网(www.php.cn)!