OSWorkflow深入分析 － 重新定义Configuration接…

在OSWorkflow中最让人恼火的就是它的接口定义！我会就这些接口的混乱展开一系列的分析，今天先说说Configuration接口

偶继承了它的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;

}

你可能奇怪我为何要继承它的接口（肯定是Bad smell），原因如下，

IWorkFlowStore 接口定义

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接口定义

/**
* 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？

其实我只是希望在createCurrentStep时按照OO的方法执行，而不是传递那些"Bad Smell"的参数，而OSWorkflow中的WorkflowStore是需要Configuration来获取的，此时为了增加一个看似合理的方法，需要分别继承Configuration与WorkflowStore；这还没有完，你需要实现一个Configuration实现！！

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;
}

}

总结

1。OSWorkflow与WorkflowStore接口的关系比较的微妙，它需要借助于Configuration接口的实现来获取到实际的WorkflowStore对象。

2。由于这样的一种微妙关系，对WorkflowStore接口的扩展必将连带着需要扩展Configuration接口，而产生这样的"果冻效应"的罪魁祸首就是由于WorkflowStore接口与Configuration接口耦合的太紧。

3。OSWorkflow并没有很好的遵守OO的设计规则，尤其在它的参数传递上，非常的差！

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