Flowable 實現【選擇下一步流程審覈人】

原理：

1. 在流程表單數據正式提交審覈前，將流程表單數據 formData 及流程執行實例 ExecutionEntity 傳遞給接口
2. 接口在流程定義取得當前節點信息並循環查找出線 SequenceFlow 還須要注意遇到網關時應該怎樣處理
3. 使用變量執行出線 SequenceFlow 條件（相似完成提交任務操做）
4. 找出第一個用戶任務UserTask 根據這個UserTask中信息，咱們就能拿到流程審覈人了
5. 最重要的一點，在第三點中使用變量去執行條件的時候，變量會被持久化至數據庫中，因此咱們必定要在事務中進行操做，操做完成後回滾清空當前事務，避免數據紊亂

項目完整源碼連接

如下是所有代碼，此邏輯僅供參考

package com.nutzfw.core.plugin.flowable.cmd;

import org.apache.commons.collections.CollectionUtils;
import org.flowable.bpmn.model.*;
import org.flowable.common.engine.impl.interceptor.Command;
import org.flowable.common.engine.impl.interceptor.CommandContext;
import org.flowable.engine.impl.persistence.entity.ExecutionEntity;
import org.flowable.engine.impl.util.condition.ConditionUtil;

import java.util.List;
import java.util.Map;

/**
 * @author huchuc@vip.qq.com
 * @date: 2019/7/9
 * 使用示例，必定要放到事務中，不然變量會入庫，致使數據紊亂
 * try {
 * Trans.begin();
 * UserTask userTask = managementService.executeCommand(new FindNextUserTaskNodeCmd(execution, bpmnModel, vars));
 * System.out.println(userTask.getId());
 * } finally {
 * Trans.clear(true);
 * }
 */
public class FindNextUserTaskNodeCmd implements Command<UserTask> {

    private final ExecutionEntity execution;
    private final BpmnModel bpmnModel;
    private Map<String, Object> vars;
    /**
     * 返回下一用戶節點
     */
    private UserTask nextUserTask;

    /**
     * @param execution 當前執行實例
     * @param bpmnModel 當前執行實例的模型
     * @param vars      參與計算流程條件的變量
     */
    public FindNextUserTaskNodeCmd(ExecutionEntity execution, BpmnModel bpmnModel, Map<String, Object> vars) {
        this.execution = execution;
        this.bpmnModel = bpmnModel;
        this.vars = vars;
    }

    /**
     * @param execution 當前執行實例
     * @param bpmnModel 當前執行實例的模型
     */
    public FindNextUserTaskNodeCmd(ExecutionEntity execution, BpmnModel bpmnModel) {
        this.execution = execution;
        this.bpmnModel = bpmnModel;
    }

    @Override
    public UserTask execute(CommandContext commandContext) {
        execution.setVariables(vars);
        FlowElement currentNode = bpmnModel.getFlowElement(execution.getActivityId());
        List<SequenceFlow> outgoingFlows = ((FlowNode) currentNode).getOutgoingFlows();
        if (CollectionUtils.isNotEmpty(outgoingFlows)) {
            this.findNextUserTaskNode(outgoingFlows, execution);
        }
        return nextUserTask;
    }


    void findNextUserTaskNode(List<SequenceFlow> outgoingFlows, ExecutionEntity execution) {
        sw:
        for (SequenceFlow outgoingFlow : outgoingFlows) {
            if (ConditionUtil.hasTrueCondition(outgoingFlow, execution)) {
                if (outgoingFlow.getTargetFlowElement() instanceof ExclusiveGateway) {
                    //只有排他網關才繼續
                    ExclusiveGateway exclusiveGateway = (ExclusiveGateway) outgoingFlow.getTargetFlowElement();
                    findNextUserTaskNode(exclusiveGateway.getOutgoingFlows(), execution);
                } else if (outgoingFlow.getTargetFlowElement() instanceof UserTask) {
                    nextUserTask = (UserTask) outgoingFlow.getTargetFlowElement();
                    //找到第一個符合條件的userTask就跳出循環
                    break sw;
                }
            }
        }
    }
}