ofbiz工作流源代码学习(1)---WfRequester接口

WfRequester接口与实现

WfRequester接口是一个和工作流流程的执行及结果有直接关系的接口，它代表了对要做的工作的请求。

 <!----><o:p></o:p>

知识点：WfRequester接口的performer是WfProcess,一个WfRequester接口可以对应好几个WfProcess<o:p></o:p>

代码示例：

          protected Map performers = null;

          this.performers = new HashMap(); //构造proces与requester的Map

          performers.put(process, requester);// registerProcess( )为requester注册process

下面的方法与performer有关：

    /**

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

*获取performer的size

     */   

    public int howManyPerformer() throws WfException {

        return performers.size();

    }

 

    /**

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

*获取performer的Iterator

*/

    public Iterator getIteratorPerformer() throws WfException {

        return performers.keySet().iterator();

    }

  

    /**

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

*获取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());

    }

 <o:p></o:p>

 <o:p></o:p>

知识点：WfRequester接口常作为启动process的对象的接口<o:p></o:p>

作为流程的启动者它通常做三件事情：

1） setting up the context

2)       start the process

3)       get the status and results

 <o:p></o:p>

知识点：WfRequester接口和WfProcess的关联，一般有两种应用场合：<o:p></o:p>

1）  工作流过程的演化 ：在这种场合下，WfActivity被精化为WfRequester,这样，它有一个执行者WfProcess。WfProcess执行一个请求就是执行一个活动。

2）  WfRequester将WfProcess连接到其它应用。

 <o:p></o:p>

知识点：WfProcess一般用void receiveEvent(WfEventAudit event)方法来将工作流事件（event）通知给request<o:p></o:p>

在发生活动的完成，中断，中止等事件时，流程必须通知requester

代码示例：

       /**

        *@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;

 <o:p></o:p>

        try {

            process = (WfProcess) event.source();  //事件来源于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);

        }

        //如果事件源不是与requester关联的process，则抛出异常

        if (process == null)

            throw new InvalidPerformer("No performer specified");

        if (!performers.containsKey(process))

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

 <o:p></o:p>

        GenericRequester req = null;

        //如果事件源是与requester关联的process，则获取状态和结果

        if (performers.containsKey(process))

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

        if (req != null)

            req.receiveResult(process.result());

    }

 <o:p></o:p>

 <o:p></o:p>

 <o:p></o:p>

 <o:p></o:p>

 <o:p></o:p>