J++ = Java + ?

在OSWorkflow中最讓人惱火的就是它的接口定義！我會就這些接口的混亂展開一系列的分析，今天先說說Configuration接口

偶繼承了它的Configuration接口

import com.company.engine.workflow.store.IWorkFlowStore;
import com.opensymphony.workflow.StoreException;
import com.opensymphony.workflow.config.Configuration;
import com.opensymphony.workflow.spi.WorkflowStore;

public interface IConfiguration extends Configuration
{
 /**
  * @deprecated getIWorkflowStore()
  */
    WorkflowStore getWorkflowStore() throws StoreException;
   
    /**
     * return WorkFlowStore which implements the interface of IWorkFlowStore
     * @return
     * @throws StoreException
     */
    IWorkFlowStore getIWorkflowStore() throws StoreException;
   
}

你可能奇怪我為何要繼承它的接口（肯定是Bad smell），原因如下，

IWorkFlowStore 接口定義

import com.opensymphony.workflow.StoreException;
import com.opensymphony.workflow.spi.Step;
import com.opensymphony.workflow.spi.WorkflowEntry;
import com.opensymphony.workflow.spi.WorkflowStore;

public interface IWorkFlowStore extends WorkflowStore
{
 
 public Step createCurrentStep(WorkflowEntry _entry , Step _step) throws StoreException;

}

WorkflowStore接口定義

    /**
     * Persists a step with the given parameters.
     *
     * @param entryId The workflow instance id.
     * @param stepId the ID of the workflow step associated with this new
     *               Step (not to be confused with the step primary key)
     * @param owner the owner of the step
     * @param startDate the start date of the step
     * @param status the status of the step
     * @param previousIds the previous step IDs
     * @return a representation of the workflow step persisted
     */
    public Step createCurrentStep(long entryId, int stepId, String owner, Date startDate, Date dueDate, String status, long[] previousIds) throws StoreException;

看到了吧？

其實我只是希望在createCurrentStep時按照OO的方法執行，而不是傳遞那些"Bad Smell"的參數，而OSWorkflow中的WorkflowStore是需要Configuration來獲取的，此時為了增加一個看似合理的方法，需要分別繼承Configuration與WorkflowStore；這還沒有完，你需要實現一個Configuration實現！！

import com.company.engine.workflow.store.IWorkFlowStore;
import com.opensymphony.workflow.StoreException;
import com.opensymphony.workflow.config.DefaultConfiguration;
import com.opensymphony.workflow.spi.WorkflowStore;

public class DefaultIConfiguration extends DefaultConfiguration implements IConfiguration
{
 
    public static DefaultIConfiguration INSTANCE = new DefaultIConfiguration();
    private transient IWorkFlowStore store = null;

 /**
  * @deprecated getIWorkflowStore()
  */
 public WorkflowStore getWorkflowStore() throws StoreException
 {
  return null;
 }

 public IWorkFlowStore getIWorkflowStore() throws StoreException
 {
  if (store == null)
  {
   String clazz = getPersistence();

   try
   {
    store = (IWorkFlowStore) Class.forName(clazz).newInstance();
   }
   catch (Exception ex)
   {
    throw new StoreException("Error creating store", ex);
   }

   store.init(getPersistenceArgs());
  }

  return store;
 }

}

總結

1。OSWorkflow與WorkflowStore接口的關系比較的微妙，它需要借助于Configuration接口的實現來獲取到實際的WorkflowStore對象。

2。由于這樣的一種微妙關系，對WorkflowStore接口的擴展必將連帶著需要擴展Configuration接口，而產生這樣的"果凍效應"的罪魁禍首就是由于WorkflowStore接口與Configuration接口耦合的太緊。

3。OSWorkflow并沒有很好的遵守OO的設計規則，尤其在它的參數傳遞上，非常的差！