要了解拒收，看懂源代码，至少要先看几次作者的原文档说明，他对拒收的定义以及约束在哪里。
拒收的含义是：当前操作者因为某种原因拒绝接收工作项，将已经发生的流转退回到前
驱环节。
可以实现拒收的场景是：
/**
*拒收工单
*/
public void rejectWorkItem(IWorkItem workItem, String comments)
throws EngineException, KernelException {
//取到工单对应的Activity
Activity thisActivity = workItem.getTaskInstance().getActivity();
//取到TaskInstance
TaskInstance thisTaskInstance = (TaskInstance) workItem
.getTaskInstance();
//如果工单处于非活动状态,或者被挂起,则不允许reject
if (workItem.getState() > 5 || workItem.getTaskInstance().isSuspended()) {
throw new EngineException(
thisTaskInstance.getProcessInstanceId(),
thisTaskInstance.getWorkflowProcess(),
thisTaskInstance.getTaskId(),
"Reject operation refused!Current work item is completed or the correspond task instance is suspended!!");
}
// 拒收操作环节只可以含有一个task
if (thisActivity.getTasks().size() > 1) {
throw new EngineException(thisTaskInstance.getProcessInstanceId(),
thisTaskInstance.getWorkflowProcess(), thisTaskInstance
.getTaskId(),
"Reject operation refused!The correspond activity has more than 1 tasks");
}
// 汇签Task不允许Reject,因为你不确定其它的人是否完成。。。
if (FormTask.ALL.equals(thisTaskInstance.getAssignmentStrategy())) {
throw new EngineException(thisTaskInstance.getProcessInstanceId(),
thisTaskInstance.getWorkflowProcess(), thisTaskInstance
.getTaskId(),
"Reject operation refused!The assignment strategy is 'ALL'");
}
//处理拒收的边界问题,不能退回到开始节点
if(thisTaskInstance.getFromActivityId().equals(IToken.FROM_START_NODE)){
throw new EngineException(
thisTaskInstance.getProcessInstanceId(),
thisTaskInstance.getWorkflowProcess(),
thisTaskInstance.getTaskId(),
"Reject operation refused!Because the from activityId equals "+IToken.FROM_START_NODE );
}
//取到持久化处理器
IPersistenceService persistenceService = this.rtCtx
.getPersistenceService();
List<ITaskInstance> siblingTaskInstancesList = null;
siblingTaskInstancesList = persistenceService
.findTaskInstancesForProcessInstanceByStepNumber(workItem
.getTaskInstance().getProcessInstanceId(),
thisTaskInstance.getStepNumber());
// split情况下，每个分支上的环节不可以执行拒收操作
if (siblingTaskInstancesList.size() > 1) {
throw new EngineException(
thisTaskInstance.getProcessInstanceId(),
thisTaskInstance.getWorkflowProcess(),
thisTaskInstance.getTaskId(),
"Reject operation refused!Because the process instance has taken a split operation.");
}
// 检查From Activity中是否有ToolTask和SubflowTask,如果有tool或subflow也不允许拒收
//注意这里，为什么可以从fromActivityID得到它的多个前驱activity,这个要看之后的synchroinizerInstance之汇聚算法
List<String> fromActivityIdList = new ArrayList<String>();
StringTokenizer tokenizer = new StringTokenizer(thisTaskInstance
.getFromActivityId(), IToken.FROM_ACTIVITY_ID_SEPARATOR);
while (tokenizer.hasMoreTokens()) {
fromActivityIdList.add(tokenizer.nextToken());
}
WorkflowProcess workflowProcess = workItem.getTaskInstance()
.getWorkflowProcess();
for (int i = 0; i < fromActivityIdList.size(); i++) {
String fromActivityId = (String) fromActivityIdList.get(i);
Activity fromActivity = (Activity) workflowProcess
.findWFElementById(fromActivityId);
List<Task> fromTaskList = fromActivity.getTasks();
for (int j = 0; j < fromTaskList.size(); j++) {
Task task = fromTaskList.get(j);
//前驱环节的task类型是tool或subflow,则不可能拒收
if (Task.TOOL.equals(task.getType())
|| Task.SUBFLOW.equals(task.getType())) {
throw new EngineException(
thisTaskInstance.getProcessInstanceId(),
thisTaskInstance.getWorkflowProcess(),
thisTaskInstance.getTaskId(),
"Reject operation refused!The previous activity contains tool-task or subflow-task");
}
}
}
// 取到工个流网实例
INetInstance netInstance = rtCtx.getKernelManager().getNetInstance(
workflowProcess.getId(),
workItem.getTaskInstance().getVersion());
if (netInstance == null) {
throw new EngineException(thisTaskInstance.getProcessInstanceId(),
thisTaskInstance.getWorkflowProcess(), thisTaskInstance
.getTaskId(),
"Not find the net instance for workflow process [id="
+ workflowProcess.getId() + ", version="
+ workItem.getTaskInstance().getVersion() + "]");
}
// 执行reject操作。
//取到当前流程会话session
IWorkflowSession session = ((IWorkflowSessionAware) workItem)
.getCurrentWorkflowSession();
//设置作了退回动作
session.setWithdrawOrRejectOperationFlag(true);
//当前步骤加1
int newStepNumber = thisTaskInstance.getStepNumber() + 1;
try {
// 首先将本WorkItem和TaskInstance cancel掉。
workItem.setComments(comments);
((WorkItem) workItem).setState(IWorkItem.CANCELED);
((WorkItem) workItem).setEndTime(rtCtx.getCalendarService()
.getSysDate());
rtCtx.getPersistenceService().saveOrUpdateWorkItem(workItem);
//终止本任务
persistenceService.abortTaskInstance(thisTaskInstance);
// 删除本环节的token
persistenceService.deleteTokensForNode(thisTaskInstance
.getProcessInstanceId(), thisTaskInstance.getActivityId());
IActivityInstance fromActivityInstance = null;
for (int i = 0; i < fromActivityIdList.size(); i++) {
String fromActivityId = (String) fromActivityIdList.get(i);
Object obj = netInstance.getWFElementInstance(fromActivityId);
fromActivityInstance = (IActivityInstance) obj;
//生成一个新的token
Token newToken = new Token();
//设置状态
((Token) newToken).setAlive(true);
//设置当前节点id
((Token) newToken).setNodeId(fromActivityId);
//设置流程实例id
newToken.setProcessInstanceId(thisTaskInstance
.getProcessInstanceId());
newToken.setProcessInstance(((TaskInstance) thisTaskInstance)
.getAliveProcessInstance());
newToken.setFromActivityId(thisTaskInstance.getActivityId());
newToken.setStepNumber(newStepNumber);
newToken.setValue(0);
persistenceService.saveOrUpdateToken(newToken);
//生成一个新的任务
this.createTaskInstances(newToken, fromActivityInstance);
//如果需要打印trance
if (rtCtx.isEnableTrace()) {
ProcessInstanceTrace trace = new ProcessInstanceTrace();
trace.setProcessInstanceId(thisTaskInstance
.getProcessInstanceId());
trace.setStepNumber(newStepNumber);
trace.setType(ProcessInstanceTrace.REJECT_TYPE);
trace.setFromNodeId(thisActivity.getId());
trace.setToNodeId(fromActivityId);
trace.setEdgeId("");
rtCtx.getPersistenceService()
.saveOrUpdateProcessInstanceTrace(trace);
}
}
//下面的这些代码我认为是没有意义的.
//得到前一个activity的一条输出边
ITransitionInstance theLeavingTransitionInstance = (ITransitionInstance) fromActivityInstance
.getLeavingTransitionInstances().get(0);
//得到前一个同步器
ISynchronizerInstance synchronizerInstance = (ISynchronizerInstance) theLeavingTransitionInstance
.getLeavingNodeInstance();
//if语句永远为真的，不会执行的。
if (synchronizerInstance.getEnteringTransitionInstances().size() > fromActivityIdList
.size()) {
Token supplementToken = new Token();
((Token) supplementToken).setAlive(false);
((Token) supplementToken).setNodeId(synchronizerInstance
.getSynchronizer().getId());
supplementToken.setProcessInstanceId(thisTaskInstance
.getProcessInstanceId());
supplementToken
.setProcessInstance(((TaskInstance) thisTaskInstance)
.getAliveProcessInstance());
supplementToken.setFromActivityId("EMPTY(created by reject)");
supplementToken
.setStepNumber(thisTaskInstance.getStepNumber() + 1);
supplementToken.setValue(synchronizerInstance.getVolume()
- theLeavingTransitionInstance.getWeight()
* fromActivityIdList.size());
persistenceService.saveOrUpdateToken(supplementToken);
}
} finally {
session.setWithdrawOrRejectOperationFlag(false);
}
}