1. 执行监听器的使用场景

1.1 人员动态分配

• 节点审批人员需要在流程运行过程中动态分配
• 当前任务节点完成的时候，指定需要指定下一个节点的处理人(比如，一个请假流程，a员工请假，需要指定下一步需要处理请假流程的领导。)。

1.2 任务节点调取业务

任务节点完成的时候，需要一些复杂业务，(比如当前节点完成的时候，需要调用我们的jms消息系统发送消息)。

任务流转到当前的节点的时候，需要监控当前任务节点的一些信息或者其他的业务信息。

当前的任务节点分配处理人的时候，需要触发自定义的一些业务。

1.3 流程上处理业务

流程开始结束的时候，需要处理业务信息。

1.4 连线上处理业务

经过任务节点的出线，也就是连线的时候，需要触发自定义的业务。

1.5 等等...

2. 执行监听器的监听事件

源码中如下：

/** Callback interface to be notified of execution events like starting a process instance,
 * ending an activity instance or taking a transition.
 *  
 * @author Tom Baeyens
 * @author Joram Barrez
 */
public interface ExecutionListener extends Serializable {

  String EVENTNAME_START = "start";//作用在流程实例的开始事件
  String EVENTNAME_END = "end";//作用在流程实例的结束事件
  String EVENTNAME_TAKE = "take";//作用在流程实例的连线上

  void notify(DelegateExecution execution) throws Exception;
}

3.流程监听器实现方式——类class

3.1 实现ExecutionListener方式

3.1.1 xml文件

流程定义文件：

<process id="process_id_or_key" name="企业信息完善审批流程模型" isExecutable="true">
    定义在流程上的监听器
    <extensionElements>
      <activiti:executionListener event="start" class="org.jeecg.modules.activiti.ext.listener.SiteReportExecutionListener"></activiti:executionListener>
    </extensionElements>
    <startEvent id="sid-2C00B4D7-2746-4AFB-904E-A2B17C071EC7"></startEvent>
    <userTask id="sid-4BDFBF55-11C2-465E-A90E-8D926ABD2D90" name="办事处审批"></userTask>
    <userTask id="sid-D3C34D06-9E4D-4EA3-BF9C-20CF9BFB0F71" name="县区审批">
    定义在任务节点上的监听
      <extensionElements>
        <activiti:executionListener event="start" class="org.jeecg.modules.activiti.ext.listener.SiteReportExecutionListener"></activiti:executionListener>
      </extensionElements>
    </userTask>
    <userTask id="sid-BCAA6507-465C-4B7D-9319-3E92909BA897" name="市审批"></userTask>
    <sequenceFlow id="sid-B010604D-1D3F-4296-8FD4-136F18A08A61" sourceRef="sid-D3C34D06-9E4D-4EA3-BF9C-20CF9BFB0F71" targetRef="sid-BCAA6507-465C-4B7D-9319-3E92909BA897"></sequenceFlow>
    <endEvent id="sid-70082386-CA2C-4B0C-BC20-40642ACBA994"></endEvent>
    <sequenceFlow id="sid-F7AD426E-DE89-42AB-8EB5-0E9873DEEA71" sourceRef="sid-BCAA6507-465C-4B7D-9319-3E92909BA897" targetRef="sid-70082386-CA2C-4B0C-BC20-40642ACBA994"></sequenceFlow>
    <sequenceFlow id="sid-9F804DC4-CBC3-455F-B11F-D82C405E93F3" sourceRef="sid-2C00B4D7-2746-4AFB-904E-A2B17C071EC7" targetRef="sid-4BDFBF55-11C2-465E-A90E-8D926ABD2D90"></sequenceFlow>
定义在流转连线上的监听器
    <sequenceFlow id="sid-9B00C62D-3355-4FEE-95B8-04C7C157D8BB" sourceRef="sid-4BDFBF55-11C2-465E-A90E-8D926ABD2D90" targetRef="sid-D3C34D06-9E4D-4EA3-BF9C-20CF9BFB0F71">
      <extensionElements>
        <activiti:executionListener event="start" class="org.jeecg.modules.activiti.ext.listener.SiteReportExecutionListener"></activiti:executionListener>
      </extensionElements>
    </sequenceFlow>
  </process>

3.1.2 监听器代码

/**
 * 执行监听器可以在流程执行中发生特定的事件时，执行外部Java代码或计算表达式。可以被捕获的事件有
 *
 * >> 流程实例的start（启动）和end（结束）。
 * >> take（进行）转移（transition）。（这里是指顺序流线 上监听事件只有take）
 * >> 活动的start和end。
 * >> 网关的start和end。
 * >> 中间事件的start和end。
 * >> 启动事件的end，和结束事件的start。
 *

 */
public class SiteReportExecutionListener implements ExecutionListener {
    private static final long serialVersionUID = 8282921521567009453L;

    @Override
    public void notify(DelegateExecution execution) throws Exception {

        //【1】监听的时间
        String eventName = execution.getEventName();//监听的事件名称
        if(EVENTNAME_START.equals(eventName)){//start

        }else if(EVENTNAME_END.equals(eventName)){//end

        }else if(EVENTNAME_TAKE.equals(eventName)){//序流线 上监听事件只有take

        }


        //【2】流程定义 以及 当前活动节点
        String currentExecutionId = execution.getId();//正在执行的流程对象的执行id
        String currentActivityId = execution.getCurrentActivityId();//正在执行的流程对象的活动节点id 获取当前的.Activityid
        String currentActivityName = execution.getCurrentActivityName();//正在执行的流程对象的活动节点名称
        String processInstanceId = execution.getProcessInstanceId();//当前流程实例id
        String processDefinitionId = execution.getProcessDefinitionId();//流程定义id
        String parentExecutionId = execution.getParentId();//获取父id，并发的时候有用

        String tenantId = execution.getTenantId();//获取TenantId 当有多个TenantId 有用

        String businessKey = execution.getBusinessKey();//业务id已经废弃
        String processBusinessKey = execution.getProcessBusinessKey();//业务id


        /**
         * 这个非常有用吧。当拿到EngineServices 对象所有的xxxService都可以拿到
         */
        EngineServices engineServices = execution.getEngineServices();
        TaskService taskService = engineServices.getTaskService();
        RuntimeService runtimeService = engineServices.getRuntimeService();

        //【3】流程变量的获取与设置,删除 增晒改查
        execution.getVariable("");
        execution.setVariable("","");
    }

 

3.2 委托类DelegateExecution介绍

/* Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.activiti.engine.delegate;

import org.activiti.engine.EngineServices;



/**
 * Execution used in {@link JavaDelegate}s and {@link ExecutionListener}s.
 * 
 * @author Tom Baeyens
 */
public interface DelegateExecution extends VariableScope {

  /** Unique id of this path of execution that can be used as a handle to provide external signals back into the engine after wait states. */
  String getId();

  /** Reference to the overall process instance */
  String getProcessInstanceId();

  /** The {@link ExecutionListener#EVENTNAME_START event name} in case this execution is passed in for an {@link ExecutionListener}  */
  String getEventName();
  
  /** The business key for this execution. Only returns a value if the delegate execution
   * is a process instance.
   *  
   * @deprecated use {@link #getProcessBusinessKey()} to get the business key for the process
   *             associated with this execution, regardless whether or not this execution is a 
   *             process-instance. 
   */
  String getBusinessKey();
  
  /**
   * The business key for the process instance this execution is associated with.
   */
  String getProcessBusinessKey();
  
  /**
   * The process definition key for the process instance this execution is associated with.
   */
  String getProcessDefinitionId();
  
  /**
   * Gets the id of the parent of this execution. If null, the execution represents a process-instance.
   */
  String getParentId();
  
  /**
   * Gets the id of the calling execution. If not null, the execution is part of a subprocess. 
   */
  String getSuperExecutionId();
  
  /**
   * Gets the id of the current activity.
   */
  String getCurrentActivityId();
  
  /**
   * Gets the name of the current activity.
   */
  String getCurrentActivityName();
  
  /**
   * Returns the tenant id, if any is set before on the process definition or process instance.
   */
  String getTenantId();
  
  /**
   * All Activiti services can be accessed through this interface.
   */
  EngineServices getEngineServices();
  
}

4. 流程监听器实现方式——表达式

同5.2 activiti任务监听器TaskListener_青苔猿猿的博客-CSDN博客

5. 流程监听器实现方式——委托表达式

 同5.2 activiti任务监听器TaskListener_青苔猿猿的博客-CSDN博客

6. 实现JavaDelegate方式

实现了接口JavaDelegate

6.1 实现代码

package org.jeecg.modules.activiti.ext.listener;

import org.activiti.engine.EngineServices;
import org.activiti.engine.RuntimeService;
import org.activiti.engine.TaskService;
import org.activiti.engine.delegate.DelegateExecution;
import org.activiti.engine.delegate.ExecutionListener;
import org.activiti.engine.delegate.JavaDelegate;

/**
 * 委托类的实现方式
 *

 */
public class SiteReportJavaDelegate implements JavaDelegate {

    /**
     * 自定义方法
     */
    public void test1(){
        System.out.println("coming_2");
    }
    @Override
    public void execute(DelegateExecution execution) throws Exception {
 

        //【1】监听的时间
        String eventName = execution.getEventName();//监听的事件名称
        if(ExecutionListener.EVENTNAME_START.equals(eventName)){//start

        }else if(ExecutionListener.EVENTNAME_END.equals(eventName)){//end

        }else if(ExecutionListener.EVENTNAME_TAKE.equals(eventName)){//序流线 上监听事件只有take

        }


        //【2】流程定义 以及 当前活动节点
        String currentExecutionId = execution.getId();//正在执行的流程对象的执行id
        String currentActivityId = execution.getCurrentActivityId();//正在执行的流程对象的活动节点id 获取当前的.Activityid
        String currentActivityName = execution.getCurrentActivityName();//正在执行的流程对象的活动节点名称
        String processInstanceId = execution.getProcessInstanceId();//当前流程实例id
        String processDefinitionId = execution.getProcessDefinitionId();//流程定义id
        String parentExecutionId = execution.getParentId();//获取父id，并发的时候有用

        String tenantId = execution.getTenantId();//获取TenantId 当有多个TenantId 有用

        String businessKey = execution.getBusinessKey();//业务id已经废弃
        String processBusinessKey = execution.getProcessBusinessKey();//业务id


        /**
         * 这个非常有用吧。当拿到EngineServices 对象所有的xxxService都可以拿到
         */
        EngineServices engineServices = execution.getEngineServices();
        TaskService taskService = engineServices.getTaskService();
        RuntimeService runtimeService = engineServices.getRuntimeService();

        //【3】流程变量的获取与设置,删除 增晒改查
        execution.getVariable("");
        execution.setVariable("","");
    }
}

6.2 xml定义三种实现方式

6.2.1  xml定义在类上

<extensionElements>
      <activiti:executionListener event="start" class="org.jeecg.modules.activiti.ext.listener.SiteReportJavaDelegate"></activiti:executionListener>
</extensionElements>

6.2.2 xml定义在表达式上

 

 

表达式处:${siteReportJavaDelegate.test1()}会执行test1方法

6.2.2 xml定义在委托表达式上

 

委托表达式:${siteReportJavaDelegate} 直接执行execute方法。