关于java:Flowable退回任意历史用户节点

应用 Flowable，退回到历史某一个节点，退回场景有：

1. 指标节点和以后节点都不在并行网关上，或者指标节点和以后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动退回，退回到并行网关后面的某一个节点上
4. 流程外部子流程(SubProcess)，子流程中退回到骨干流程中某一个节点
5. 流程外部子流程(SubProcess)，骨干流程退回到子流程中某一个节点
6. 流程内部子流程(CallActivity)，子流程中退回到骨干流程中某一个节点、骨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 能够退回到让子流程从新开始，但不是子流程中的某一个节点，残缺源码详见：
springboot：https://gitee.com/zjm16/zjmzx…
springcloud：https://gitee.com/zjm16/zjmzx…
具体流程图可参见残缺源码门路 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);
        // 只反对从用户工作退回
        if (!(sourceFlowElement instanceof UserTask)) {throw new FlowableException("Task with id:" + taskId + "is not a UserTask");
        }

        FlowNode targetFlowElement = (FlowNode) process.getFlowElement(targetActivityId, true);
        // 退回节点到以后节点不可达到，不容许退回
        if (!FlowableUtils.isReachable(process, targetFlowElement, sourceFlowElement)) {throw new FlowableException("Cannot back to [" + targetActivityId + "]");
        }

        // ps: 指标节点如果绝对以后节点是在子流程外部，则无奈间接退回，目前解决是只能退回到子流程开始节点
        String[] sourceAndTargetRealActivityId = FlowableUtils.getSourceAndTargetRealActivityId(sourceFlowElement, targetFlowElement);
        // 理论应操作的以后节点 ID
        String sourceRealActivityId = sourceAndTargetRealActivityId[0];
        // 理论应操作的指标节点 ID
        String targetRealActivityId = sourceAndTargetRealActivityId[1];

        Map<String, Set<String>> specialGatewayNodes = FlowableUtils.getSpecialGatewayElements(process);
        // 以后节点处在的并行网关 list
        List<String> sourceInSpecialGatewayList = new ArrayList<>();
        // 指标节点处在的并行网关 list
        List<String> targetInSpecialGatewayList = new ArrayList<>();
        setSpecialGatewayList(sourceRealActivityId, targetRealActivityId, specialGatewayNodes, sourceInSpecialGatewayList,
                targetInSpecialGatewayList);

        // 理论应筛选的节点 ID
        Set<String> sourceRealAcitivtyIds = null;
        // 若退回指标节点绝对以后节点在并行网关中，则要找到绝对以后节点最近的这个并行网关，后续做非凡解决
        String targetRealSpecialGateway = null;

        // 1. 指标节点和以后节点都不在并行网关中
        if (targetInSpecialGatewayList.isEmpty() && sourceInSpecialGatewayList.isEmpty()) {sourceRealAcitivtyIds = Sets.newHashSet(sourceRealActivityId);
        }
        // 2. 指标节点不在并行网关中、以后节点在并行网关中
        else if (targetInSpecialGatewayList.isEmpty() && !sourceInSpecialGatewayList.isEmpty()) {sourceRealAcitivtyIds = specialGatewayNodes.get(sourceInSpecialGatewayList.get(0));
        }
        // 3. 指标节点在并行网关中、以后节点不在并行网关中
        else if (!targetInSpecialGatewayList.isEmpty() && sourceInSpecialGatewayList.isEmpty()) {sourceRealAcitivtyIds = Sets.newHashSet(sourceRealActivityId);
            targetRealSpecialGateway = targetInSpecialGatewayList.get(0);
        }
        // 4. 指标节点和以后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 {
                // 以后节点最内层并行网关不被指标节点最内层并行网关蕴含
                // 或了解为以后节点绝对指标节点在并行网关外
                // 只筛选以后节点的 execution
                if (sourceInSpecialGatewayList.size() == diffSpecialGatewayLevel) {sourceRealAcitivtyIds = Sets.newHashSet(sourceRealActivityId);
                }
                // 以后节点绝对指标节点在并行网关内，应筛选绝对指标节点最近的并行网关的所有节点的 execution
                else {sourceRealAcitivtyIds = specialGatewayNodes.get(sourceInSpecialGatewayList.get(diffSpecialGatewayLevel));
                }
                // 指标节点最内层并行网关蕴含以后节点最内层并行网关
                // 或了解为指标节点绝对以后节点在并行网关外
                // 不做解决
                if (targetInSpecialGatewayList.size() == diffSpecialGatewayLevel) { }
                // 指标节点绝对以后节点在并行网关内
                else {targetRealSpecialGateway = targetInSpecialGatewayList.get(diffSpecialGatewayLevel);
                }
            }
        }

        // 筛选须要解决的 execution
        List<ExecutionEntity> realExecutions = this.getRealExecutions(commandContext, processInstanceId, task.getExecutionId(), sourceRealActivityId,
                sourceRealAcitivtyIds);
        // 执行退回，间接跳转到理论的 targetRealActivityId
        List<String> realExecutionIds = realExecutions.stream().map(ExecutionEntity::getId).collect(Collectors.toList());
        runtimeService.createChangeActivityStateBuilder().processInstanceId(processInstanceId)
                .moveExecutionsToSingleActivityId(realExecutionIds, targetRealActivityId).changeState();
        // 指标节点绝对以后节点处于并行网关内，须要非凡解决，须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) {// 指标节点绝对以后节点处于并行网关，须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();
            // 解决指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;
    }
}