Apache Mina 學習筆記(4)-Session

Session是Apache的核心，每當一個用戶端串連到達時，就會有一個新的Session被建立，直到該串連關閉。Session被用來儲存串連，以及各種資訊。

Session有如下幾種狀態：

Connected : the session has been created and is availableIdle : 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 timeIdle for write : no write has actually been made for a period of timeIdle for both : no read nor write for a period of timeClosing : 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.

表示Session的狀態轉換關係：

以下幾個參數可以用來配置Session

receive buffer size
sending buffer size
Idle time
Write timeOut

系統管理使用者自訂的屬性：

例如，如果你想跟蹤一個使用者從會話被建立之後發送了多少個請求，那麼它可以很容易存入這種映射：只要建立一個key關聯到value就行。

...  int counterValue = session.getAttribute( "counter" );  session.setAttribute( "counter", counterValue + 1 );  ...

我們採用key/value 對的方式儲存屬性到會話中，這種key/value對可以通過session的容器讀取，添加或刪除。

定義container

正如我們所說，這個容器是一個key/value容器，預設是一種映射，當然也可以定義成其他的資料結構。當Session被建立時我們可以實現一個介面和一個factory用來建立容器。下面的程式碼片段樣本了在Session初始化時如何建立容器（看不懂，這個到底什麼意思？）

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;   }

過濾鏈

每個會話會關聯一些過濾鏈，用來處理到來的請求或者出去的資料。每個會話都會指定單獨的過濾鏈，大多數情況下，我們會用在會話中用很多相同的過濾鏈。

統計

Each session also keep a track of records about what has been done for the session :number of bytes received/sentnumber of messages received/sentIdle statusthroughputand many other useful informations.Handler

最後，同樣重要的是，一個Handler要附著於一個Session上，用來處理常式的訊息。這個Handler也會發送包作為回應，只要簡單的調用write方法即可：

...  session.write( <your message> );  ...

以上就是Apache Mina 學習筆記(4)-Session的內容，更多相關內容請關注topic.alibabacloud.com（www.php.cn）！

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