ofbiz工作流程原始碼學習(1)–WfRequester介面

 WfRequester介面是一個和工作流程流程的執行及結果有直接關係的介面，它代表了對要做的工作的請求。

 知識點：WfRequester介面的performer是WfProcess,一個WfRequester介面可以對應好幾個WfProcess

程式碼範例：

          protected Map performers = null;

          this.performers = new HashMap(); //構造proces與requester的Map

          performers.put(process, requester);// registerProcess( )為requester註冊process

下面的方法與performer有關：

    /**

*@see org.ofbiz.core.workflow.WfRequester#howManyPerformer()

*擷取performer的size

     */   

    public int howManyPerformer() throws WfException {

        return performers.size();

    }

      /**

     * @see org.ofbiz.core.workflow.WfRequester#getIteratorPerformer()

*擷取performer的Iterator

*/

    public Iterator getIteratorPerformer() throws WfException {

        return performers.keySet().iterator();

    }

       /**

     * @see org.ofbiz.core.workflow.WfRequester#getSequencePerformer(int)

*擷取List形式的performer

*/

    public List getSequencePerformer(int maxNumber) throws WfException {

        if (maxNumber > 0)

            return new ArrayList(performers.keySet()).subList(0, (maxNumber - 1));

        return new ArrayList(performers.keySet());

    }

 知識點：WfRequester介面常作為啟動process的對象的介面

作為流程的啟動者它通常做三件事情：

1） setting up the context

2)       start the process

3)       get the status and results

 知識點：WfRequester介面和WfProcess的關聯，一般有兩種應用場合：

1）  工作流程過程的演化 ：在這種場合下，WfActivity被精化為WfRequester,這樣，它有一個執行者WfProcess。WfProcess執行一個請求就是執行一個活動。

2）  WfRequester將WfProcess串連到其它應用。

 知識點：WfProcess一般用void receiveEvent(WfEventAudit event)方法來將工作流程事件（event）通知給request

在發生活動的完成，中斷，中止等事件時，流程必須通知requester

程式碼範例：

       /**

        *@see org.ofbiz.core.workflow.WfRequester#receiveEvent()

        */

    public synchronized void receiveEvent(WfEventAudit event) throws WfException, InvalidPerformer {

        // Should the source of the audit come from the process? if so use this.

        WfProcess process = null;

         try {

            process = (WfProcess) event.source();  //事件來源於process

        } catch (SourceNotAvailable sna) {

            throw new InvalidPerformer("Could not get the performer", sna);

        } catch (ClassCastException cce) {

            throw new InvalidPerformer("Not a valid process object", cce);

        }

        //如果事件來源不是與requester關聯的process，則拋出異常

        if (process == null)

            throw new InvalidPerformer("No performer specified");

        if (!performers.containsKey(process))

            throw new InvalidPerformer("Performer not assigned to this requester");

         GenericRequester req = null;

        //如果事件來源是與requester關聯的process，則擷取狀態和結果

        if (performers.containsKey(process))

            req = (GenericRequester) performers.get(process);

        if (req != null)

            req.receiveResult(process.result());

    }