在实际的业务中，可能存在存在这么一种情况，当流程运行到某一个环节时，可能需要同时多个人的参与，才可以完成此环节。此时就可以用到activiti的多实例来解决此问题。

一、将一个节点设置成多实例的方法：

要把一个节点设置为多实例，节点xml元素必须设置一个multiInstanceLoopCharacteristics子元素。

    当isSequential=true时，表示的顺序执行，即虽然该节点有多条任务，但只有上一条执行完，才可以执行下一条。

当isSequential=false时，表示的并行执行，即该节点下的多条任务可以同时执行。

二、设置会签环节的参与者：

<strong>activiti:collection：用于执行该会签环节的参与参与的人，此处是使用的一个名叫pers的流程变量
</strong>

<strong>activiti:elementVariable：此处表示的是每一个分支都有一个名叫per的流程变量，和上方的activiti:assignee结合使用就可以执行该分支应该由谁来处理。</strong>

三.指定会签环节的结束条件：

     当画红线的部分返回一个true的时候，该会签环节结束。进入下一个流程执行的环节.

completionCondition中写的是juel表达式。其中的mulitiInstance如果是和spring整合了，就是spring管理的bean的id，否则就是流程变量的key.

四、会签环节中涉及的几个默认的流程变量

1.nrOfInstances 该会签环节中总共有多少个实例

2.nrOfActiveInstances 当前活动的实例的数量，即还没有 完成的实例数量。

3.nrOfCompletedInstances 已经完成的实例的数量

五、代码如下：

1.分配会签环节的人：

/**
 * 分配下一环节会签的人
 *
 * @author huan
 *
 */
public class AssgineeMultiInstancePer implements JavaDelegate {
    @Override
    public void execute(DelegateExecution execution) throws Exception {
        System.out.println("设置会签环节的人员.");
        execution.setVariable("pers", Arrays.asList("张三", "李四", "王五", "赵六"));
    }
}

2.多实例判断完成的条件：（注意：有于我没有和spring整合，所以此类要实现Serializable接口）

/**
 * 多实例完成的条件判断
 * @author huan
 */
public class MulitiInstanceCompleteTask implements Serializable {
    private static final long serialVersionUID = 1L;
    public boolean completeTask(DelegateExecution execution) {
        System.out.println("总的会签任务数量：" + execution.getVariable("nrOfInstances") + "当前获取的会签任务数量：" + execution.getVariable("nrOfActiveInstances") + " - " + "已经完成的会签任务数量：" + execution.getVariable("nrOfCompletedInstances"));
        System.out.println("I am invoked.");
        return false;
    }
}

3.会签环节中的一个监听器：

/**
 * 测试会签过程中监听器的执行情况
 * @author huan
 */
public class TestLinstener implements TaskListener {
    private static final long serialVersionUID = -5754522101489239675L;
    @Override
    public void notify(DelegateTask delegateTask) {
        System.out.print(delegateTask.getId() + " - " + delegateTask.getProcessInstanceId() + " - " + delegateTask.getEventName() + " - " + delegateTask.getTaskDefinitionKey());
    }
}

4.测试代码：

/**
 * 测试会签
 * @author huan
 */
public class TestMultiInstance {
    @Test
    public void testProcess() {
        ProcessEngine processEngine = ProcessEngines.getDefaultProcessEngine();
        RepositoryService repositoryService = processEngine.getRepositoryService();
        RuntimeService runtimeService = processEngine.getRuntimeService();
        TaskService taskService = processEngine.getTaskService();
        Deployment deploy = repositoryService.createDeployment()//
                .name("会签流程测试")//
                .addInputStream("multiInstances.bpmn", this.getClass().getResourceAsStream("multiInstances.bpmn"))//
                .addInputStream("multiInstances.png", this.getClass().getResourceAsStream("multiInstances.png"))//
                .deploy();
        System.out.println(deploy.getId() + " " + deploy.getName());
        Map<String, Object> variables = new HashMap<String, Object>();
        variables.put("mulitiInstance", new MulitiInstanceCompleteTask());
        ProcessInstance pi = runtimeService.startProcessInstanceByKey("multiInstances",variables);
        System.out.println(pi.getId() + "  " + pi.getActivityId());
        Task task1 = taskService.createTaskQuery().processInstanceId(pi.getId()).taskAssignee("张三").singleResult();
        System.out.println(task1.getId() + " - " + task1.getAssignee() + " - " + task1.getProcessInstanceId() + " - " + task1.getProcessDefinitionId());
        Task task2 = taskService.createTaskQuery().processInstanceId(pi.getId()).taskAssignee("李四").singleResult();
        System.out.println(task2.getId() + " - " + task2.getAssignee() + " - " + task2.getProcessInstanceId() + " - " + task2.getProcessDefinitionId());
        Task task3 = taskService.createTaskQuery().processInstanceId(pi.getId()).taskAssignee("王五").singleResult();
        System.out.println(task3.getId() + " - " + task3.getAssignee() + " - " + task3.getProcessInstanceId() + " - " + task3.getProcessDefinitionId());
        Task task4 = taskService.createTaskQuery().processInstanceId(pi.getId()).taskAssignee("赵六").singleResult();
        if (task4 != null) {
            System.out.println(task4.getId() + " - " + task4.getAssignee() + " - " + task4.getProcessInstanceId() + " - " + task4.getProcessDefinitionId());
        }
        Task task5 = taskService.createTaskQuery().processInstanceId(pi.getId()).taskAssignee("钱七").singleResult();
        System.out.println(task5);
        taskService.complete(task1.getId());
        taskService.complete(task2.getId());
        taskService.complete(task3.getId());
        Task task6 = taskService.createTaskQuery().processInstanceId(pi.getId()).taskAssignee("钱七").singleResult();
        System.out.println(task6);
        taskService.complete(task4.getId());
        Task task7 = taskService.createTaskQuery().processInstanceId(pi.getId()).taskAssignee("钱七").singleResult();
        System.out.println(task7);
        taskService.complete(task7.getId());
        ProcessInstance processInstance = runtimeService.createProcessInstanceQuery().processInstanceId(pi.getId()).singleResult();
        if (null == processInstance) {
            System.out.println("流程完成.");
        }
    }
}

5.流程文件：

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:activiti="http://activiti.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC" xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://www.activiti.org/test">
  <process id="multiInstances" name="流程会签测试" isExecutable="true">
    <startEvent id="startevent1" name="Start"></startEvent>
    <sequenceFlow id="flow1" sourceRef="startevent1" targetRef="A001"></sequenceFlow>
    <serviceTask id="A001" name="设置下一环节的人" activiti:class="com.huan.activiti.liuyang.会签.AssgineeMultiInstancePer"></serviceTask>
    <userTask id="B001" name="会签环节" activiti:assignee="${per}">
      <extensionElements>
        <activiti:taskListener event="complete" class="com.huan.activiti.liuyang.会签.TestLinstener"></activiti:taskListener>
      </extensionElements>
      <multiInstanceLoopCharacteristics isSequential="false" activiti:collection="pers" activiti:elementVariable="per">
        <completionCondition>${mulitiInstance.completeTask(execution)}</completionCondition>
      </multiInstanceLoopCharacteristics>
    </userTask>
    <sequenceFlow id="flow2" sourceRef="A001" targetRef="B001"></sequenceFlow>
    <userTask id="C001" name="会签后的环节" activiti:assignee="钱七"></userTask>
    <sequenceFlow id="flow3" sourceRef="B001" targetRef="C001"></sequenceFlow>
    <endEvent id="endevent1" name="End"></endEvent>
    <sequenceFlow id="flow4" sourceRef="C001" targetRef="endevent1"></sequenceFlow>
  </process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_multiInstances">
    <bpmndi:BPMNPlane bpmnElement="multiInstances" id="BPMNPlane_multiInstances">
      <bpmndi:BPMNShape bpmnElement="startevent1" id="BPMNShape_startevent1">
        <omgdc:Bounds height="35.0" width="35.0" x="100.0" y="240.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="A001" id="BPMNShape_A001">
        <omgdc:Bounds height="71.0" width="117.0" x="190.0" y="222.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="B001" id="BPMNShape_B001">
        <omgdc:Bounds height="55.0" width="105.0" x="380.0" y="230.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="C001" id="BPMNShape_C001">
        <omgdc:Bounds height="55.0" width="105.0" x="561.0" y="230.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="endevent1" id="BPMNShape_endevent1">
        <omgdc:Bounds height="35.0" width="35.0" x="740.0" y="240.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge bpmnElement="flow1" id="BPMNEdge_flow1">
        <omgdi:waypoint x="135.0" y="257.0"></omgdi:waypoint>
        <omgdi:waypoint x="190.0" y="257.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="flow2" id="BPMNEdge_flow2">
        <omgdi:waypoint x="307.0" y="257.0"></omgdi:waypoint>
        <omgdi:waypoint x="380.0" y="257.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="flow3" id="BPMNEdge_flow3">
        <omgdi:waypoint x="485.0" y="257.0"></omgdi:waypoint>
        <omgdi:waypoint x="561.0" y="257.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="flow4" id="BPMNEdge_flow4">
        <omgdi:waypoint x="666.0" y="257.0"></omgdi:waypoint>
        <omgdi:waypoint x="740.0" y="257.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</definitions>

7.流程图：

  如若那个地方写的不对，欢迎指出。