使用Flowable，退回到历史某一个节点，退回场景有：
1.目标节点和当前节点都不在并行网关上，或者目标节点和当前节点在同一个并行网关的同一个分支
2.退回到并行网关分支中的某一个节点上
3.并行网关中的某一个分支节点上发起退回，退回到并行网关前面的某一个节点上
4.流程内部子流程(SubProcess)，子流程中退回到主干流程中某一个节点
5.流程内部子流程(SubProcess)，主干流程退回到子流程中某一个节点
6.流程外部子流程(CallActivity)，子流程中退回到主干流程中某一个节点、主干流程退回到子流程中某一个节点
我的思路，目前已实现 1~4 ，其中 5 可以退回到让子流程重新开始，但不是子流程中的某一个节点，完整源码详见：
springboot：https://gitee.com/zjm16/zjmzxfzhl
springcloud：https://gitee.com/zjm16/zjmzxfzhl-cloud
详细流程图可参见完整源码路径 zjmzxfzhl/src/main/resources/processes_test 下的流程文件
具体实现的java文件BackUserTaskCmd.java
package com.zjmzxfzhl.modules.flowable.common.cmd;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import org.flowable.bpmn.model.FlowNode;
import org.flowable.bpmn.model.Process;
import org.flowable.bpmn.model.UserTask;
import org.flowable.common.engine.api.FlowableException;
import org.flowable.common.engine.api.FlowableObjectNotFoundException;
import org.flowable.common.engine.impl.interceptor.Command;
import org.flowable.common.engine.impl.interceptor.CommandContext;
import org.flowable.engine.RuntimeService;
import org.flowable.engine.impl.delegate.ActivityBehavior;
import org.flowable.engine.impl.persistence.entity.ExecutionEntity;
import org.flowable.engine.impl.persistence.entity.ExecutionEntityManager;
import org.flowable.engine.impl.util.CommandContextUtil;
import org.flowable.engine.impl.util.ProcessDefinitionUtil;
import org.flowable.task.api.Task;
import org.flowable.task.service.impl.persistence.entity.TaskEntity;
import com.google.common.collect.Sets;
import com.zjmzxfzhl.modules.flowable.constant.FlowableConstant;
import com.zjmzxfzhl.modules.flowable.util.FlowableUtils;
/**
* @author 庄金明
* @date 2020年3月23日
*/
public class BackUserTaskCmd implements Command<String>, Serializable {
public static final long serialVersionUID = 1L;
protected RuntimeService runtimeService;
protected String taskId;
protected String targetActivityId;
public BackUserTaskCmd(RuntimeService runtimeService, String taskId, String targetActivityId) {
this.runtimeService = runtimeService;
this.taskId = taskId;
this.targetActivityId = targetActivityId;
}
@Override
public String execute(CommandContext commandContext) {
if (targetActivityId == null || targetActivityId.length() == 0) {
throw new FlowableException("TargetActivityId cannot be empty");
}
TaskEntity task = CommandContextUtil.getTaskService().getTask(taskId);
if (task == null) {
throw new FlowableObjectNotFoundException("task " + taskId + " doesn't exist", Task.class);
}
String sourceActivityId = task.getTaskDefinitionKey();
String processInstanceId = task.getProcessInstanceId();
String processDefinitionId = task.getProcessDefinitionId();
Process process = ProcessDefinitionUtil.getProcess(processDefinitionId);
FlowNode sourceFlowElement = (FlowNode) process.getFlowElement(sourceActivityId, true);
// 只支持从用户任务退回
if (!(sourceFlowElement instanceof UserTask)) {
throw new FlowableException("Task with id:" + taskId + " is not a UserTask");
}
FlowNode targetFlowElement = (FlowNode) process.getFlowElement(targetActivityId, true);
// 退回节点到当前节点不可达到，不允许退回
if (!FlowableUtils.isReachable(process, targetFlowElement, sourceFlowElement)) {
throw new FlowableException("Cannot back to [" + targetActivityId + "]");
}
// ps:目标节点如果相对当前节点是在子流程内部，则无法直接退回，目前处理是只能退回到子流程开始节点
String[] sourceAndTargetRealActivityId = FlowableUtils.getSourceAndTargetRealActivityId(sourceFlowElement, targetFlowElement);
// 实际应操作的当前节点ID
String sourceRealActivityId = sourceAndTargetRealActivityId[0];
// 实际应操作的目标节点ID
String targetRealActivityId = sourceAndTargetRealActivityId[1];
Map<String, Set<String>> specialGatewayNodes = FlowableUtils.getSpecialGatewayElements(process);
// 当前节点处在的并行网关list
List<String> sourceInSpecialGatewayList = new ArrayList<>();
// 目标节点处在的并行网关list
List<String> targetInSpecialGatewayList = new ArrayList<>();
setSpecialGatewayList(sourceRealActivityId, targetRealActivityId, specialGatewayNodes, sourceInSpecialGatewayList,
targetInSpecialGatewayList);
// 实际应筛选的节点ID
Set<String> sourceRealAcitivtyIds = null;
// 若退回目标节点相对当前节点在并行网关中，则要找到相对当前节点最近的这个并行网关，后续做特殊处理
String targetRealSpecialGateway = null;
// 1.目标节点和当前节点都不在并行网关中
if (targetInSpecialGatewayList.isEmpty() && sourceInSpecialGatewayList.isEmpty()) {
sourceRealAcitivtyIds = Sets.newHashSet(sourceRealActivityId);
}
// 2.目标节点不在并行网关中、当前节点在并行网关中
else if (targetInSpecialGatewayList.isEmpty() && !sourceInSpecialGatewayList.isEmpty()) {
sourceRealAcitivtyIds = specialGatewayNodes.get(sourceInSpecialGatewayList.get(0));
}
// 3.目标节点在并行网关中、当前节点不在并行网关中
else if (!targetInSpecialGatewayList.isEmpty() && sourceInSpecialGatewayList.isEmpty()) {
sourceRealAcitivtyIds = Sets.newHashSet(sourceRealActivityId);
targetRealSpecialGateway = targetInSpecialGatewayList.get(0);
}
// 4.目标节点和当前节点都在并行网关中
else {
int diffSpecialGatewayLevel = FlowableUtils.getDiffLevel(sourceInSpecialGatewayList, targetInSpecialGatewayList);
// 在并行网关同一层且在同一分支
if (diffSpecialGatewayLevel == -1) {
sourceRealAcitivtyIds = Sets.newHashSet(sourceRealActivityId);
} else {
// 当前节点最内层并行网关不被目标节点最内层并行网关包含
// 或理解为当前节点相对目标节点在并行网关外
// 只筛选当前节点的execution
if (sourceInSpecialGatewayList.size() == diffSpecialGatewayLevel) {
sourceRealAcitivtyIds = Sets.newHashSet(sourceRealActivityId);
}
// 当前节点相对目标节点在并行网关内，应筛选相对目标节点最近的并行网关的所有节点的execution
else {
sourceRealAcitivtyIds = specialGatewayNodes.get(sourceInSpecialGatewayList.get(diffSpecialGatewayLevel));
}
// 目标节点最内层并行网关包含当前节点最内层并行网关
// 或理解为目标节点相对当前节点在并行网关外
// 不做处理
if (targetInSpecialGatewayList.size() == diffSpecialGatewayLevel) {
}
// 目标节点相对当前节点在并行网关内
else {
targetRealSpecialGateway = targetInSpecialGatewayList.get(diffSpecialGatewayLevel);
}
}
}
// 筛选需要处理的execution
List<ExecutionEntity> realExecutions = this.getRealExecutions(commandContext, processInstanceId, task.getExecutionId(), sourceRealActivityId,
sourceRealAcitivtyIds);
// 执行退回，直接跳转到实际的 targetRealActivityId
List<String> realExecutionIds = realExecutions.stream().map(ExecutionEntity::getId).collect(Collectors.toList());
runtimeService.createChangeActivityStateBuilder().processInstanceId(processInstanceId)
.moveExecutionsToSingleActivityId(realExecutionIds, targetRealActivityId).changeState();
// 目标节点相对当前节点处于并行网关内，需要特殊处理，需要手动生成并行网关汇聚节点(_end)的execution数据
if (targetRealSpecialGateway != null) {
createTargetInSpecialGatewayEndExecutions(commandContext, realExecutions, process, targetInSpecialGatewayList, targetRealSpecialGateway);
}
return targetRealActivityId;
}
private void setSpecialGatewayList(String sourceActivityId, String targetActivityId, Map<String, Set<String>> specialGatewayNodes,
List<String> sourceInSpecialGatewayList, List<String> targetInSpecialGatewayList) {
for (Map.Entry<String, Set<String>> entry : specialGatewayNodes.entrySet()) {
if (entry.getValue().contains(sourceActivityId)) {
sourceInSpecialGatewayList.add(entry.getKey());
}
if (entry.getValue().contains(targetActivityId)) {
targetInSpecialGatewayList.add(entry.getKey());
}
}
}
private void createTargetInSpecialGatewayEndExecutions(CommandContext commandContext, List<ExecutionEntity> excutionEntitys, Process process,
List<String> targetInSpecialGatewayList, String targetRealSpecialGateway) {
// 目标节点相对当前节点处于并行网关，需要手动生成并行网关汇聚节点(_end)的execution数据
String parentExecutionId = excutionEntitys.iterator().next().getParentId();
ExecutionEntityManager executionEntityManager = CommandContextUtil.getExecutionEntityManager(commandContext);
ExecutionEntity parentExecutionEntity = executionEntityManager.findById(parentExecutionId);
int index = targetInSpecialGatewayList.indexOf(targetRealSpecialGateway);
for (; index < targetInSpecialGatewayList.size(); index++) {
String targetInSpecialGateway = targetInSpecialGatewayList.get(index);
String targetInSpecialGatewayEndId = targetInSpecialGateway + FlowableConstant.SPECIAL_GATEWAY_END_SUFFIX;
FlowNode targetInSpecialGatewayEnd = (FlowNode) process.getFlowElement(targetInSpecialGatewayEndId, true);
int nbrOfExecutionsToJoin = targetInSpecialGatewayEnd.getIncomingFlows().size();
// 处理目标节点所处的分支以外的分支,即 总分枝数-1 = nbrOfExecutionsToJoin - 1
for (int i = 0; i < nbrOfExecutionsToJoin - 1; i++) {
ExecutionEntity childExecution = executionEntityManager.createChildExecution(parentExecutionEntity);
childExecution.setCurrentFlowElement(targetInSpecialGatewayEnd);
ActivityBehavior activityBehavior = (ActivityBehavior) targetInSpecialGatewayEnd.getBehavior();
activityBehavior.execute(childExecution);
}
}
}
private List<ExecutionEntity> getRealExecutions(CommandContext commandContext, String processInstanceId, String taskExecutionId,
String sourceRealActivityId, Set<String> activityIds) {
ExecutionEntityManager executionEntityManager = CommandContextUtil.getExecutionEntityManager(commandContext);
ExecutionEntity taskExecution = executionEntityManager.findById(taskExecutionId);
List<ExecutionEntity> executions = executionEntityManager.findChildExecutionsByProcessInstanceId(processInstanceId);
Set<String> parentExecutionIds = FlowableUtils.getParentExecutionIdsByActivityId(executions, sourceRealActivityId);
String realParentExecutionId = FlowableUtils.getParentExecutionIdFromParentIds(taskExecution, parentExecutionIds);
List<ExecutionEntity> childExecutions = executionEntityManager.findExecutionsByParentExecutionAndActivityIds(realParentExecutionId,
activityIds);
return childExecutions;
}
}
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