struts2与jbpm4的简单集成

当公司领导指定使用struts2作为某项目的显示层实现技术时，而该项目使用了jbpm。
当使用jbpm时，正常情况下是要显示未知数量的业务表单页面。
一般情况下，在使用struts2(本人使用的情况下)的一般情况下，页面控制是已经写在struts的配置文件当中，也就是说要显示的页面基本是已知的了(未知页面，显然是无法配置的)，因此一般情况下，当有新业务时，或者业务流程发生变化时(任务节点新增与删除等)，就会导致业务表单页面的新增与删除，然后这种以xml配置方式，显然是无法满足需求的。
我们知道在使用springmvc时，viewname是可以在程序里指定，这样业务表单也是可以在程序里指定的，可以避免xml配置的不灵活性。显然struts2肯定也应该提供了这样的方式。
扩展以下两个类即可：
1、StrutsActionProxyFactory；
2、DefaultActionInvocation；

我们需要覆盖DefaultActionInvocation.createResult方法，
因为该方法的默认实现是从resultmappings里根据resultcode（action相关方法返回值）获取视图的，因此如果业务表单为在struts2的配置文件里进行配置，应该是会抛出异常。因此，我们只要覆盖该方法，并根据resultcode寻找视图(而不是从resultmapping里寻找)。一般情况，resultcode可以是业务表单页面的相对路径。

为了使用我们自己的ActionInvocation，就必须覆盖StrutsActionProxyFactory.createActionProxy方法，因为该方法已经指定返回StrutsActionProxy，我们覆盖StrutsActionProxyFactory.createActionProxy方法，返回我们自己的ActionInvocation。

具体实现如下：

public class IcomStrutsActionInvocation extends DefaultActionInvocation {

	public static final String JBPM_PREFIX = "icom:";

	public IcomStrutsActionInvocation(Map<String, Object> extraContext, boolean pushAction) {
		super(extraContext, pushAction);
	}

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public Result createResult() throws Exception {

		if (resultCode != null && resultCode.startsWith(JBPM_PREFIX)) {// 如果是工作流表单(返回代码必须以icom:开头哦)
			Map<String, String> resultParams = new HashMap<String, String>();
			resultParams.put("location", resultCode.replace(JBPM_PREFIX, ""));
			ResultConfig resultConfig = new ResultConfig.Builder(resultCode,
					ServletDispatcherResult.class.getName()).addParams(resultParams)
					.build();

			return objectFactory.buildResult(resultConfig, invocationContext
					.getContextMap());
		} else {
			return super.createResult();
		}

	}

}

public class IcomStrtuts2ActionFactory extends StrutsActionProxyFactory {

	public ActionProxy createActionProxy(String namespace, String actionName,
			String methodName, Map<String, Object> extraContext,
			boolean executeResult, boolean cleanupContext) {
		
		ActionInvocation inv = new IcomStrutsActionInvocation(extraContext, true);
        container.inject(inv);
        
        return super.createActionProxy(inv, namespace, actionName, methodName, executeResult, cleanupContext);
	}
	
	
}

因为struts-default.xml文件是没有配置我们自己的实现类，因此需要在struts的配置文件添加我们自己的相关实现类，配置如下：

<struts>
	<bean class="com.icom.tech.struts2.IcomStrtuts2ActionFactory"
		name="default" type="com.opensymphony.xwork2.ActionProxyFactory" />
...
    </struts>

struts-action返回resultcode例子：

public String forTask() throws Exception {

		TaskService taskService = processEngine.getTaskService();
		task = taskService.getTask(taskId);
		if (null == task)
			throw new NullPointerException("id为：" + taskId + " 的任务已经被处理...");
		taskService.getVariableNames(taskId);
		Map<String, Object> variables = taskService.getVariables(taskId,
				taskService.getVariableNames(taskId));
		if (!(null == variables || variables.isEmpty())) {
			ValueStack stack = ActionContext.getContext().getValueStack();
			Iterator<String> it = variables.keySet().iterator();
			while (it.hasNext()) {
				String key = it.next();
				logger.info("将要压入的参数：" + key + " 值为：" + variables.get(key));
				Object value = variables.get(key);
				stack.set(key, value);
			}
		}
		if(flag){
			// 获取表单页面路径信息
			 return IcomStrutsActionInvocation.JBPM_PREFIX+retriveFormResource();
		}
		

		return IcomStrutsActionInvocation.JBPM_PREFIX
				+ task.getFormResourceName();
	}
	
	

	private String retriveFormResource() throws Exception {

		String formResourceName = task.getFormResourceName();

		String excutionId = task.getExecutionId();

		Execution e = processEngine.getExecutionService().findExecutionById(
				excutionId);

		ProcessDefinition pd = processEngine.getRepositoryService()
				.createProcessDefinitionQuery().processDefinitionId(
						e.getProcessDefinitionId()).uniqueResult();

		DeploymentImpl deployment = (DeploymentImpl) processEngine
				.getRepositoryService().createDeploymentQuery().deploymentId(
						pd.getDeploymentId()).uniqueResult();

		
		String path = deployment.getId() + "/" + pd.getId() + "/"
				+ formResourceName;
		File formFile = new File(formBaseDir, path);
		
		// 首先判断文件是否存在，不存在则创建表单文件
		if (!formFile.exists())
			
			synchronized (processEngine) {
				if(!formFile.getParentFile().exists()){
					formFile.getParentFile().mkdirs();
				}

				byte[] buf = deployment.getBytes(formResourceName);

				// 写入特定存放目录中
				FileOutputStream fos = new FileOutputStream(formFile);
				fos.write(buf);
				fos.close();
			}

		return DEFAULT_FORM_BASE_DIR + path;
	}

以下是jpdl编写的流程定义文件片段：

<task assignee="${user}" name="材料补正" form="printSupplyMaterial.jsp">
		<on event="start">
			<event-listener factory="businessInstanceListener" method="getInstance" />
		</on>
		<on event="timeout">
			<timer duedate="${tc_supplyMaterial_timeout}" />
			<event-listener class="com.icom.cpb.workflow.listener.ChangeColorListener" auto-wire="true" >
				<property name="fontColor">
					<string value="${tc_supplyMaterial_timeout_color}"/>
				</property>
				<property name="businessInstanceService">
					<ref object="businessInstanceService"/>
				</property>
			</event-listener>
		</on>
		<transition name="未补全" to="不受理" >
			<event-listener class="com.icom.cpb.workflow.listener.IncreaseDocNumberListner" >
				<property name="userInfoService">
					<ref object="userInfoService" />
				</property>
				<property name="docNumberService">
					<ref object="docNumberService" />
				</property>
				<property name="docnumberName">
					<string value="不予受理" />
				</property>
				<property name="variableName">
					<string value="recode" />
				</property>
			</event-listener>
			<event-listener class="com.icom.cpb.workflow.listener.ResetCreateTimeListener">
		 		<property name="businessInstanceService">
		 			<ref object="businessInstanceService"/>
		 		</property>
		 	</event-listener>
		</transition>
		<!-- 
		<transition name="已补全" to="受理" >
			<event-listener class="com.icom.cpb.workflow.listener.IncreaseDocNumberListner" >
				<property name="userInfoService">
					<ref object="userInfoService" />
				</property>
				<property name="docNumberService">
					<ref object="docNumberService" />
				</property>
				<property name="docnumberName">
					<string value="受理" />
				</property>
				<property name="variableName">
					<string value="accode" />
				</property>
			</event-listener>
		</transition>
		 -->
		 <transition name="已补全" to="受理" >
	 		<event-listener class="com.icom.cpb.workflow.listener.ClearMaterialsListener" >
	 			<property name="businessInstanceService">
		 			<ref object="businessInstanceService"/>
		 		</property>
		 		<property name="receivedDocInfoService">
		 			<ref object="receivedDocInfoService"/>
		 		</property>
	 		</event-listener>
		 	<event-listener class="com.icom.cpb.workflow.listener.ResetCreateTimeListener">
		 		<property name="businessInstanceService">
		 			<ref object="businessInstanceService"/>
		 		</property>
		 	</event-listener>
		 	<event-listener class="com.icom.cpb.workflow.listener.IncreaseDocNumberListner" >
				<property name="userInfoService">
					<ref object="userInfoService" />
				</property>
				<property name="docNumberService">
					<ref object="docNumberService" />
				</property>
				<property name="docnumberName">
					<string value="受理" />
				</property>
				<property name="variableName">
					<string value="accode" />
				</property>
			</event-listener>
		 </transition>
	</task>