activiti(7)：监听器之流程监听及spring注入

这篇文章主要记录流程监听器的部分用法，整个环境实在集成在spring下，ssm环境：

三个监听器：

A:普通javaBean：

package com.abc.activiti.listenner;import org.activiti.engine.delegate.DelegateExecution;public class JavaExpressionActivitiListenner {public void expression(DelegateExecution execution) throws Exception {System.out.println("executionId：" + execution.getId() + " ActivitiListenner" + this.toString());}}

B:实现ExecutionListener接口：

package com.abc.activiti.listenner;import org.activiti.engine.delegate.DelegateExecution;import org.activiti.engine.delegate.DelegateTask;import org.activiti.engine.delegate.ExecutionListener;import org.activiti.engine.delegate.TaskListener;public class ActivitiListenner implements TaskListener, ExecutionListener {/** *  */private static final long serialVersionUID = -3759054058055401826L;@Overridepublic void notify(DelegateExecution execution) throws Exception {System.out.println("xml流程：" + execution.getId() + " ActivitiListenner" + this.toString());}@Overridepublic void notify(DelegateTask delegateTask) {System.out.println("xml任务：" + delegateTask.getId() + " ActivitiListenner" + this.toString());}}

C:实现JavaDelegate接口

package com.abc.activiti.listenner;import org.activiti.engine.delegate.DelegateExecution;import org.activiti.engine.delegate.JavaDelegate;public class JavaDelegateActivitiListenner implements JavaDelegate {@Overridepublic void execute(DelegateExecution execution) throws Exception {System.out.println("executionId：" + execution.getId() + " ActivitiListenner" + this.toString());}}

第一种尝试：javaClass配置实现监听

流程设计：

流程非常短：启动-办理-结束，并配置了三个监听器

监听器配置：

<process id="abc" name="流程监听注入" isExecutable="true"><extensionElements><activiti:executionListener event="start"class="com.abc.activiti.listenner.xxxListenner"></activiti:executionListener><activiti:executionListener event="end"class="com.abc.activiti.listenner.xxxListenner"></activiti:executionListener></extensionElements><startEvent id="startevent1" name="Start"></startEvent><userTask id="usertask1" name="User Task"></userTask><sequenceFlow id="flow1" sourceRef="startevent1"targetRef="usertask1"></sequenceFlow><endEvent id="endevent1" name="End"></endEvent><sequenceFlow id="flow2" sourceRef="usertask1" targetRef="endevent1"><extensionElements><activiti:executionListener event="take"class="com.abc.activiti.listenner.xxxListenner"></activiti:executionListener></extensionElements></sequenceFlow></process>

A类监听测试：

2017-09-16 10:36:25.816 [http-nio-8080-exec-3] ERROR c.a.a.controller.ActivitiController.exception - 处理请求http://localhost:8080/abc-master/activiti/start?null 时出错。完整异常栈堆信息org.activiti.engine.ActivitiIllegalArgumentException: com.abc.activiti.listenner.JavaExpressionActivitiListenner doesn't implement interface org.activiti.engine.delegate.ExecutionListener nor interface org.activiti.engine.delegate.JavaDelegate

启动流程时报错，说明通过javaClass配置activiti的流程监听器必须实现org.activiti.engine.delegate.ExecutionListener或者org.activiti.engine.delegate.JavaDelegate接口

B类监听测试：

流程启动-办理-结束，三个监听器的方法分别被执行：执行结果如下：

xml流程：7f7aa2be-9a89-11e7-9d02-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@39ca6dcdxml流程：7f7aa2be-9a89-11e7-9d02-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@306a75c6xml流程：7f7aa2be-9a89-11e7-9d02-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@342664da

测试表明，通过加载java class的方式去加载实现了ExecutionListener接口的bean，可以顺利实现流程监听，但是每次获取的监听器都是一个新对象；

C类监听测试：

执行结果如下：

executionId：eebefb34-9a89-11e7-b1f2-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@26d8afc4executionId：eebefb34-9a89-11e7-b1f2-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@38835b92executionId：eebefb34-9a89-11e7-b1f2-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@21dcaa6e

不出所料，其结果与B类监听一致；

进一步测试：spring容器注入bean：

可以设想一下，javaClass加载监听器的时，每次都是activitiEngine通过反射产生新的对象，因此此种方式下通过spring管理去注入可能会失败：

对实现了JavaDelegate的监听器进行改造：

package com.abc.activiti.listenner;import org.activiti.engine.delegate.DelegateExecution;import org.activiti.engine.delegate.JavaDelegate;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import com.abc.activiti.service.ActivitiService;@Servicepublic class JavaDelegateActivitiListenner implements JavaDelegate {@Autowiredprivate ActivitiService activitiService;@Overridepublic void execute(DelegateExecution execution) throws Exception {System.out.println("executionId：" + execution.getId() + " ActivitiListenner" + this.toString()+ "  spring容器注入bean：" + activitiService.toString());}}

测试结果：

妥妥的空指针，注入失败：

2017-09-16 10:57:01.760 [http-nio-8080-exec-3] ERROR c.a.a.controller.ActivitiController.exception - 处理请求http://localhost:8080/abc-master/activiti/start?null 时出错。完整异常栈堆信息java.lang.NullPointerException: nullat com.abc.activiti.listenner.JavaDelegateActivitiListenner.execute(JavaDelegateActivitiListenner.java:19) ~[JavaDelegateActivitiListenner.class:na]at org.activiti.engine.impl.delegate.JavaDelegateInvocation.invoke(JavaDelegateInvocation.java:34) ~[activiti-engine-5.20.0.jar:na]

对实现了ExecutionListener的监听器进行改造：

package com.abc.activiti.listenner;import org.activiti.engine.delegate.DelegateExecution;import org.activiti.engine.delegate.DelegateTask;import org.activiti.engine.delegate.ExecutionListener;import org.activiti.engine.delegate.TaskListener;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import com.abc.activiti.service.ActivitiService;@Servicepublic class ActivitiListenner implements TaskListener, ExecutionListener {/** *  */private static final long serialVersionUID = -3759054058055401826L;@Autowiredprivate ActivitiService activitiService;@Overridepublic void notify(DelegateExecution execution) throws Exception {System.out.println("xml流程：" + execution.getId() + " ActivitiListenner" + this.toString());System.out.println("activitiService: " + activitiService.toString());}@Overridepublic void notify(DelegateTask delegateTask) {System.out.println("xml任务：" + delegateTask.getId() + " ActivitiListenner" + this.toString());}}

测试结果：

xml流程：03ec2a11-9a8b-11e7-903c-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@5de11ac22017-09-16 10:59:11.541 [http-nio-8080-exec-3] ERROR c.a.a.controller.ActivitiController.exception - 处理请求http://localhost:8080/abc-master/activiti/start?null 时出错。完整异常栈堆信息java.lang.NullPointerException: nullat com.abc.activiti.listenner.ActivitiListenner.notify(ActivitiListenner.java:26) ~[ActivitiListenner.class:na]at org.activiti.engine.impl.delegate.ExecutionListenerInvocation.invoke(ExecutionListenerInvocation.java:34) ~[activiti-engine-5.20.0.jar:na]

以上两组结果表明，spring只是将其纳入管理，但并成功注入到activitiEngine中。

第二种尝试：expression配置实现监听

监听器配置：

<process id="abc" name="流程监听注入" isExecutable="true"><extensionElements><activiti:executionListener event="start"expression="${javaExpressionActivitiListenner.expression(execution)}"></activiti:executionListener><activiti:executionListener event="end"expression="${javaExpressionActivitiListenner.expression(execution)}"></activiti:executionListener></extensionElements><startEvent id="startevent1" name="Start"></startEvent><userTask id="usertask1" name="User Task"></userTask><sequenceFlow id="flow1" sourceRef="startevent1"targetRef="usertask1"></sequenceFlow><endEvent id="endevent1" name="End"></endEvent><sequenceFlow id="flow2" sourceRef="usertask1" targetRef="endevent1"><extensionElements><activiti:executionListener event="take"expression="${javaExpressionActivitiListenner.expression(execution)}"></activiti:executionListener></extensionElements></sequenceFlow></process>

A类监听测试：

需要注意的是，此时通过expression表达式注入时，是的

2017-09-16 11:27:29.420 [http-nio-8080-exec-3] ERROR c.a.a.controller.ActivitiController.exception - 处理请求http://localhost:8080/abc-master/activiti/start?null 时出错。完整异常栈堆信息org.activiti.engine.ActivitiException: Unknown property used in expression: ${javaExpressionActivitiListenner.expression(execution)}at org.activiti.engine.impl.el.JuelExpression.getValue(JuelExpression.java:53) ~[activiti-engine-5.20.0.jar:na]......Caused by: org.activiti.engine.impl.javax.el.PropertyNotFoundException: Cannot resolve identifier 'javaExpressionActivitiListenner'at org.activiti.engine.impl.juel.AstIdentifier.eval(AstIdentifier.java:83) ~[activiti-engine-5.20.0.jar:5.20.0]

监听器改造：

package com.abc.activiti.listenner;import org.activiti.engine.delegate.DelegateExecution;import org.springframework.stereotype.Component;@Componentpublic class JavaExpressionActivitiListenner {public void expression(DelegateExecution execution) throws Exception {System.out.println("executionId：" + execution.getId() + " ActivitiListenner" + this.toString());}}

测试结果如下：

executionId：ddd3f07e-9a8d-11e7-9fc5-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaExpressionActivitiListenner@420a38c6executionId：ddd3f07e-9a8d-11e7-9fc5-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaExpressionActivitiListenner@420a38c6executionId：ddd3f07e-9a8d-11e7-9fc5-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaExpressionActivitiListenner@420a38c6

B类监听测试：

测试结果：

xml流程：2175ef09-9a8e-11e7-9af4-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@2f68610cxml流程：2175ef09-9a8e-11e7-9af4-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@2f68610cxml流程：2175ef09-9a8e-11e7-9af4-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@2f68610c

C类监听测试：

测试结果：

executionId：719dc30a-9a8d-11e7-9ac9-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@7374d21eexecutionId：719dc30a-9a8d-11e7-9ac9-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@7374d21eexecutionId：719dc30a-9a8d-11e7-9ac9-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@7374d21e

进一步测试：spring注入bean：

测试结果：

xml流程：2b882f40-9a91-11e7-9325-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@42e9857eactivitiService: com.abc.activiti.service.ActivitiService@2f9b021fxml流程：2b882f40-9a91-11e7-9325-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@42e9857eactivitiService: com.abc.activiti.service.ActivitiService@2f9b021fxml流程：2b882f40-9a91-11e7-9325-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@42e9857eactivitiService: com.abc.activiti.service.ActivitiService@2f9b021f

此处仅提供A类监听测试结果，其余测试结果均一致，以上测试结果表明，使用expression表达式江容器中的bean作为监听器注入到activitiEngine中是一种非常灵活强大的方式。

第三种尝试：delegate expression配置实现监听

监听器配置：

<process id="abc" name="流程监听注入" isExecutable="true"><extensionElements><activiti:executionListener event="start"delegateExpression="${activitiListenner}"></activiti:executionListener><activiti:executionListener event="end"delegateExpression="${activitiListenner}"></activiti:executionListener></extensionElements><startEvent id="startevent1" name="Start"></startEvent><userTask id="usertask1" name="User Task"></userTask><sequenceFlow id="flow1" sourceRef="startevent1"targetRef="usertask1"></sequenceFlow><endEvent id="endevent1" name="End"></endEvent><sequenceFlow id="flow2" sourceRef="usertask1" targetRef="endevent1"><extensionElements><activiti:executionListener event="take"delegateExpression="${activitiListenner}"></activiti:executionListener></extensionElements></sequenceFlow></process>

A类监听测试：

2017-09-16 12:21:54.134 [http-nio-8080-exec-3] ERROR c.a.a.controller.ActivitiController.exception - 处理请求http://localhost:8080/abc-master/activiti/start?null 时出错。完整异常栈堆信息org.activiti.engine.ActivitiIllegalArgumentException: Delegate expression ${javaExpressionActivitiListenner} did not resolve to an implementation of interface org.activiti.engine.delegate.ExecutionListener nor interface org.activiti.engine.delegate.JavaDelegateat org.activiti.engine.impl.bpmn.listener.DelegateExpressionExecutionListener.notify(DelegateExpressionExecutionListener.java:57) ~[activiti-engine-5.20.0.jar:5.20.0]at org.activiti.engine.impl.pvm.runtime.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:42) ~[activiti-engine-5.20.0.jar:na]

B类监听测试：

xml流程：fcc6c8ba-9a95-11e7-826d-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@71425d05activitiService: com.abc.activiti.service.ActivitiService@72a765d5xml流程：fcc6c8ba-9a95-11e7-826d-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@71425d05activitiService: com.abc.activiti.service.ActivitiService@72a765d5xml流程：fcc6c8ba-9a95-11e7-826d-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@71425d05activitiService: com.abc.activiti.service.ActivitiService@72a765d5

C类监听测试：

executionId：c96567e2-9a95-11e7-b7e3-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@6f660921  spring容器注入bean：com.abc.activiti.service.ActivitiService@1dc6b66aexecutionId：c96567e2-9a95-11e7-b7e3-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@6f660921  spring容器注入bean：com.abc.activiti.service.ActivitiService@1dc6b66aexecutionId：c96567e2-9a95-11e7-b7e3-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@6f660921  spring容器注入bean：com.abc.activiti.service.ActivitiService@1dc6b66a

以上测试结果表明：

通过delegate expression配置容器中的监听器时，仍然需要实现ExecutionListener或者JavaDelegate接口

总结：

1通过javaClass加载指定类，这种硬编码的形式管理监听器，是将class字节码文件交由activitiEngine处理，每次需要的时候则由engine通过反射构建实例对象，spring无法管理；

2通过delegate expression配置容器中的bean作为监听器，${类名}；需要bean自身实现org.activiti.engine.delegate.ExecutionListener或者

org.activiti.engine.delegate.JavaDelegate接口，并重写对应的方法，在改监听器被调用时，会默认制定重写方法中的逻辑，此时，bean对象是由spring管理，可以与容器无缝对接；

3通过expression配置容器中的bean作为监听器，${类名.方法名(参数名)}；这是最为灵活也最为强大的方法，可以使用任意的bean，也可以自定义将要执行的方法，与spring容器无缝对接，与业务逻辑完美契合。