1. 任务监听器定义

任务监听器用于在特定的任务相关事件发生时，执行自定义的Java逻辑或表达式

2.监听器监听的事件

String EVENTNAME_CREATE = "create";创建）：当任务已经创建，并且所有任务参数都已经设置时触发
String EVENTNAME_ASSIGNMENT = "assignment";（指派）：当任务已经指派给某人时触发。请注意：当流程执行到达用户任务时，create事件触发前，首先触发assignment事件。这看起来不是自然顺序，但是有实际原因的：当收到create事件时，我们通常希望查看任务的所有参数，包括办理人。
String EVENTNAME_COMPLETE = "complete"（完成）：当任务已经完成，从运行时数据中删除前触发。
String EVENTNAME_DELETE = "delete"（删除）：在任务即将被删除前触发。请注意当任务通过completeTask正常完成时也会触发

注意：assignment事件比create先执行。

3. 任务监听实现方式——类class

实现接口org.activiti.engine.delegate.TaskListener

在流程定义文件中用class属性来指定该监听器

3.1 TaskListener源码

/*** @author Tom Baeyens*/
public interface TaskListener extends Serializable {//create（创建）：当任务已经创建，并且所有任务参数都已经设置时触发String EVENTNAME_CREATE = "create";/**assignment（指派）：当任务已经指派给某人时触发。请注意：当流程执行到达用户任务时，
create事件触发前，首先触发assignment事件。这看起来不是自然顺序，
但是有实际原因的：当收到create事件时，我们通常希望查看任务的所有参数，包括办理人。**/String EVENTNAME_ASSIGNMENT = "assignment";//（完成）：当任务已经完成，从运行时数据中删除前触发String EVENTNAME_COMPLETE = "complete";//（删除）：在任务即将被删除前触发。请注意当任务通过completeTask正常完成时也会触发String EVENTNAME_DELETE = "delete";/*** Not an actual event, used as a marker-value for {@link TaskListener}s that should be called for all events,* including {@link #EVENTNAME_CREATE}, {@link #EVENTNAME_ASSIGNMENT} and {@link #EVENTNAME_COMPLETE} and {@link #EVENTNAME_DELETE}.*/String EVENTNAME_ALL_EVENTS = "all";void notify(DelegateTask delegateTask);
}

xml文件中定义

<userTask id="usertask2" name="User Task" activiti:assignee="c"><extensionElements><activiti:taskListener event="all" class="com.daling.ch1.listener.MyExecutionListener"></activiti:taskListener></extensionElements>
</userTask>

3.2 类的定义

任务监听器中我们可以拿到DelegateTask对象，这个对象可以让我们操作activiti引擎中的一些东西，下面看一下DelegateTask类中的定义主要访法。

import lombok.extern.slf4j.Slf4j;
import org.activiti.engine.delegate.DelegateTask;
import org.activiti.engine.delegate.TaskListener;/*** 任务监听器用于在特定的任务相关事件发生时，执行自定义的Java逻辑或表达式** 任务监听器支持下列属性：*  event（事件）（必填）：任务监听器将被调用的任务事件类型。可用的事件有：*         create（创建）：当任务已经创建，并且所有任务参数都已经设置时触发。*         assignment（指派）：当任务已经指派给某人时触发。请注意：当流程执行到达用户任务时，create事件触发前，首先触发*         assignment事件。这看起来不是自然顺序，但是有实际原因的：当收到create事件时，我们通常希望查看任务的所有参数，包括*         办理人。*         complete（完成）：当任务已经完成，从运行时数据中删除前触发。*         delete（删除）：在任务即将被删除前触发。请注意当任务通过completeTask正常完成时也会触发**   class：需要调用的代理类。这个类必须实现 org.activiti.engine.delegate.TaskListener 接口***   expression：（不能与class属性一起使用）：指定在事件发生时要执行的表达式。可以为被调用的对象传递 DelegateTask 对象与事件名（使用 task.eventName ）作为参数****   delegateExpression：可以指定一个能够解析为 TaskListener 接口实现类对象的表达式。与服务任务类似***/
@Slf4j
public class SiteReportUserTask implements TaskListener {private static final long serialVersionUID = 3654543511891213996L;@Overridepublic void notify(DelegateTask delegateTask) {log.info("creattime: {}",delegateTask.getCreateTime());log.info("getProcessInstanceId: {}",delegateTask.getProcessInstanceId());log.info("数据库中的taskId主键: {}",delegateTask.getId());log.info("任务名称: {}",delegateTask.getName());delegateTask.setName("修改任务名称");log.info("获取任务的描述信息: {}",delegateTask.getDescription());delegateTask.setDescription("修改任务的描述信息");/*** lower priority: [0..19] lowest, [20..39] low, [40..59] normal, [60..79] high* [80..100] highest任务处理的优先级范围是0-100*/log.info("任务处理的优先级范围是0-100: {}",delegateTask.getPriority());delegateTask.setPriority(1); /** 修改优先级*/log.info("获取流程实例id: {}",delegateTask.getProcessInstanceId());log.info("获取流程获取执行id: {}",delegateTask.getExecutionId());log.info("获取流程定义id: {}",delegateTask.getProcessDefinitionId());/** 添一个加候选人 *///void addCandidateUser(String userId);/** 添加候选人集合 *///void addCandidateUsers(Collection<String> candidateUsers);/** 添加候选组 *///void addCandidateGroup(String groupId);String eventName = delegateTask.getEventName();if (EVENTNAME_CREATE.endsWith(eventName)) {System.out.println("create=========");}else if (EVENTNAME_ASSIGNMENT.endsWith(eventName)) {System.out.println("assignment========");}else if (EVENTNAME_COMPLETE.endsWith(eventName)) {System.out.println("complete===========");}else if (EVENTNAME_DELETE.endsWith(eventName)) {System.out.println("delete=============");}}
}

3.3 监听器委托类DelegateTask

/* 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 java.util.Collection;
import java.util.Date;
import java.util.Set;import org.activiti.engine.ActivitiObjectNotFoundException;
import org.activiti.engine.task.DelegationState;
import org.activiti.engine.task.IdentityLink;
import org.activiti.engine.task.IdentityLinkType;/*** @author Joram Barrez*/
public interface DelegateTask extends VariableScope {/** DB id of the task. */String getId();/** Name or title of the task. */String getName();/** Change the name of the task. */void setName(String name);/** Free text description of the task. */String getDescription();/** Change the description of the task */void setDescription(String description);/** indication of how important/urgent this task is with a number between * 0 and 100 where higher values mean a higher priority and lower values mean * lower priority: [0..19] lowest, [20..39] low, [40..59] normal, [60..79] high * [80..100] highest */int getPriority();/** indication of how important/urgent this task is with a number between * 0 and 100 where higher values mean a higher priority and lower values mean * lower priority: [0..19] lowest, [20..39] low, [40..59] normal, [60..79] high * [80..100] highest */void setPriority(int priority);/** Reference to the process instance or null if it is not related to a process instance. */String getProcessInstanceId();/** Reference to the path of execution or null if it is not related to a process instance. */String getExecutionId();/** Reference to the process definition or null if it is not related to a process. */String getProcessDefinitionId();/** The date/time when this task was created */Date getCreateTime();/** The id of the activity in the process defining this task or null if this is not related to a process */String getTaskDefinitionKey();/** Indicated whether this task is suspended or not. */boolean isSuspended();/** The tenant identifier of this task */String getTenantId();/** The form key for the user task */String getFormKey();/** Change the form key of the task */void setFormKey(String formKey);/** Returns the execution currently at the task. */DelegateExecution getExecution();/** Returns the event name which triggered the task listener to fire for this task. */String getEventName();/** The current {@link org.activiti.engine.task.DelegationState} for this task. */DelegationState getDelegationState();/** Adds the given user as a candidate user to this task. */void addCandidateUser(String userId);/** Adds multiple users as candidate user to this task. */void addCandidateUsers(Collection<String> candidateUsers);/** Adds the given group as candidate group to this task */void addCandidateGroup(String groupId);/** Adds multiple groups as candidate group to this task. */void addCandidateGroups(Collection<String> candidateGroups);/** The {@link User.getId() userId} of the person responsible for this task. */String getOwner();/** The {@link User.getId() userId} of the person responsible for this task.*/void setOwner(String owner);/** The {@link User.getId() userId} of the person to which this task is delegated. */String getAssignee();/** The {@link User.getId() userId} of the person to which this task is delegated. */void setAssignee(String assignee);/** Due date of the task. */Date getDueDate();/** Change due date of the task. */void setDueDate(Date dueDate);/** The category of the task. This is an optional field and allows to 'tag' tasks as belonging to a certain category. */String getCategory();/** Change the category of the task. This is an optional field and allows to 'tag' tasks as belonging to a certain category. */void setCategory(String category);/*** Involves a user with a task. The type of identity link is defined by the given identityLinkType.* @param userId id of the user involve, cannot be null.* @param identityLinkType type of identityLink, cannot be null (@see {@link IdentityLinkType}).* @throws ActivitiObjectNotFoundException when the task or user doesn't exist.*/void addUserIdentityLink(String userId, String identityLinkType);/*** Involves a group with group task. The type of identityLink is defined by the given identityLink.* @param groupId id of the group to involve, cannot be null.* @param identityLinkType type of identity, cannot be null (@see {@link IdentityLinkType}).* @throws ActivitiObjectNotFoundException when the task or group doesn't exist.*/void addGroupIdentityLink(String groupId, String identityLinkType);/*** Convenience shorthand for {@link #deleteUserIdentityLink(String, String)}; with type {@link IdentityLinkType#CANDIDATE}* @param userId id of the user to use as candidate, cannot be null.* @throws ActivitiObjectNotFoundException when the task or user doesn't exist.*/void deleteCandidateUser(String userId);/*** Convenience shorthand for {@link #deleteGroupIdentityLink(String, String, String)}; with type {@link IdentityLinkType#CANDIDATE}* @param groupId id of the group to use as candidate, cannot be null.* @throws ActivitiObjectNotFoundException when the task or group doesn't exist.*/void deleteCandidateGroup(String groupId);/*** Removes the association between a user and a task for the given identityLinkType.* @param userId id of the user involve, cannot be null.* @param identityLinkType type of identityLink, cannot be null (@see {@link IdentityLinkType}).* @throws ActivitiObjectNotFoundException when the task or user doesn't exist.*/void deleteUserIdentityLink(String userId, String identityLinkType);/*** Removes the association between a group and a task for the given identityLinkType.* @param groupId id of the group to involve, cannot be null.* @param identityLinkType type of identity, cannot be null (@see {@link IdentityLinkType}).* @throws ActivitiObjectNotFoundException when the task or group doesn't exist.*/void deleteGroupIdentityLink(String groupId, String identityLinkType);/*** Retrieves the candidate users and groups associated with the task.* @return set of {@link IdentityLink}s of type {@link IdentityLinkType#CANDIDATE}.*/Set<IdentityLink> getCandidates();
}

4. 监听实现方式——表达式expression

使用activiti:taskListener元素的expression属性来指定监听器

4.1 普通表达式

4.1.1 定义表达式类

package org.jeecg.modules.activiti.ext.expression;import lombok.extern.slf4j.Slf4j;
import org.activiti.engine.delegate.DelegateTask;
import org.activiti.engine.delegate.TaskListener;import java.io.Serializable;@Slf4j
public class TaskListenerExpression implements Serializable {private static final long serialVersionUID = 6880733208262796584L;public void execute(DelegateTask delegateTask) {log.info("creattime: {}", delegateTask.getCreateTime());log.info("getProcessInstanceId: {}", delegateTask.getProcessInstanceId());log.info("数据库中的taskId主键: {}", delegateTask.getId());log.info("任务名称: {}", delegateTask.getName());delegateTask.setName("修改任务名称");log.info("获取任务的描述信息: {}", delegateTask.getDescription());delegateTask.setDescription("修改任务的描述信息");/*** lower priority: [0..19] lowest, [20..39] low, [40..59] normal, [60..79] high* [80..100] highest任务处理的优先级范围是0-100*/log.info("任务处理的优先级范围是0-100: {}", delegateTask.getPriority());delegateTask.setPriority(1); /** 修改优先级*/log.info("获取流程实例id: {}", delegateTask.getProcessInstanceId());log.info("获取流程获取执行id: {}", delegateTask.getExecutionId());log.info("获取流程定义id: {}", delegateTask.getProcessDefinitionId());/** 添一个加候选人 *///void addCandidateUser(String userId);/** 添加候选人集合 *///void addCandidateUsers(Collection<String> candidateUsers);/** 添加候选组 *///void addCandidateGroup(String groupId);String eventName = delegateTask.getEventName();if (TaskListener.EVENTNAME_CREATE.endsWith(eventName)) {System.out.println("create=========");} else if (TaskListener.EVENTNAME_ASSIGNMENT.endsWith(eventName)) {System.out.println("assignment========");} else if (TaskListener.EVENTNAME_COMPLETE.endsWith(eventName)) {System.out.println("complete===========");} else if (TaskListener.EVENTNAME_DELETE.endsWith(eventName)) {System.out.println("delete=============");}}
}

4.1.2 xml定义

4.1.3 如何调用

在流程执行到某个阶段，或者启动流程实例的时候，用下面代码调用

Map<String,Object> map=new HashMap<>();
map.put("taskListenerExpression",new TaskListenerExpression());
runtimeService.startProcessInstanceByKey("taskListener_study2",map);

4.2 spring表达式

spring表达式只是对4.1的优化处理，我们只需要在自己定义的TaskListenerExpression类上加注解管理该bean。在表达式中直接调用。如下其他都不用改表：


@Slf4j
@Service("listenerSpringExpression")
public class TaskListenerExpression implements Serializable {private static final long serialVersionUID = 6880733208262796584L;public void execute(DelegateTask delegateTask) {log.info("creattime: {}", delegateTask.getCreateTime());log.info("getProcessInstanceId: {}", delegateTask.getProcessInstanceId());

xml处的调用也不需要改变。当任务执行到该节点的时候，会直接调用该spring管理的bean。

5. 监听器实现方式——委托表达式delegateExpression

委托表达式和表达式区别：

（1）委托表达式需要实现TaskListener和序列化接口

（2）xml中直接写实现类的变量名，不用写方法名称，默认调取接口方法名

5.1 表达式类的实现

package org.jeecg.modules.activiti.ext.expression;import lombok.extern.slf4j.Slf4j;
import org.activiti.engine.delegate.DelegateTask;
import org.activiti.engine.delegate.TaskListener;import java.io.Serializable;/*** 监听器 委托表达式的实现*/
@Slf4j
public class TaskListenerDelegateExpression implements TaskListener,Serializable {private static final long serialVersionUID = 6880733208262796584L;public void notify(DelegateTask delegateTask) {log.info("creattime: {}", delegateTask.getCreateTime());log.info("getProcessInstanceId: {}", delegateTask.getProcessInstanceId());log.info("数据库中的taskId主键: {}", delegateTask.getId());log.info("任务名称: {}", delegateTask.getName());delegateTask.setName("修改任务名称");log.info("获取任务的描述信息: {}", delegateTask.getDescription());delegateTask.setDescription("修改任务的描述信息");/*** lower priority: [0..19] lowest, [20..39] low, [40..59] normal, [60..79] high* [80..100] highest任务处理的优先级范围是0-100*/log.info("任务处理的优先级范围是0-100: {}", delegateTask.getPriority());delegateTask.setPriority(1); /** 修改优先级*/log.info("获取流程实例id: {}", delegateTask.getProcessInstanceId());log.info("获取流程获取执行id: {}", delegateTask.getExecutionId());log.info("获取流程定义id: {}", delegateTask.getProcessDefinitionId());/** 添一个加候选人 *///void addCandidateUser(String userId);/** 添加候选人集合 *///void addCandidateUsers(Collection<String> candidateUsers);/** 添加候选组 *///void addCandidateGroup(String groupId);String eventName = delegateTask.getEventName();if (TaskListener.EVENTNAME_CREATE.endsWith(eventName)) {System.out.println("create=========");} else if (TaskListener.EVENTNAME_ASSIGNMENT.endsWith(eventName)) {System.out.println("assignment========");} else if (TaskListener.EVENTNAME_COMPLETE.endsWith(eventName)) {System.out.println("complete===========");} else if (TaskListener.EVENTNAME_DELETE.endsWith(eventName)) {System.out.println("delete=============");}}
}

5.2 xml流程文件的定义

<userTask id="sid-11585CC1-BD05-4589-8379-78A6EFA8DCCC" name="县区控尘办审批"><extensionElements><activiti:taskListener event="create" delegateExpression="${taskListenerDelegateExpression}"></activiti:taskListener></extensionElements>
</userTask>

5.3 监听器的使用

在流程到达该任务节点时，就会从流程变量中获取taskListenerDelegateExpression,并执行notify方法

Map<String,Object> map=new HashMap<>();
map.put("taskListenerDelegateExpression",new TaskListenerDelegateExpression());
runtimeService.startProcessInstanceByKey("taskListener_study2",map);

6. 字段属性使用

6.1 xml文件定义

<userTask id="sid-D92E1931-D96E-41EF-AF34-5FC059076F1D" name="办事处审批"><extensionElements><activiti:taskListener event="complete" class="org.jeecg.modules.activiti.ext.listener.SiteReportUserTask"><activiti:field name="fieldNameA"><activiti:string><![CDATA[我是字符串内容666]]></activiti:string></activiti:field></activiti:taskListener></extensionElements>
</userTask>

通过多次设置字段的值可以得知：

fieldNameA取值优先级：第1个字符串>第3个字符串> 第二个表达式

6.2 类中使用

@Slf4j
public class SiteReportUserTask implements TaskListener {private static final long serialVersionUID = 3654543511891213996L;private Expression fieldNameA;@Overridepublic void notify(DelegateTask delegateTask) {Object o=fieldNameA.getValue(delegateTask);String str=fieldNameA.getExpressionText();... ...

若在表达式中输入:${1==1},则上述代码输出是：o:true；str:${1==1}。自己体会，一个是值，一个是内容字符串。

7. 总结

一个用户任务节点可以创建多个监听器
class类方式实现监听器，不需要在流程变量中加入监听器对象
expression方式,监听器可以是一个普通的java类，但要实现序列化接口,需要在流程变量中加入监听器类的对象，或者加入spring容器中
delegateExpression,监听器要同时实现TaskListener和序列化接口，需要在流程变量中加入监听器类的对象

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