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;
@Override
public void notify(DelegateExecution execution) throws Exception {
System.out.println("xml流程：" + execution.getId() + " ActivitiListenner" + this.toString());
}
@Override
public 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 {
@Override
public 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：
class="com.abc.activiti.listenner.xxxListenner">
class="com.abc.activiti.listenner.xxxListenner">
targetRef="usertask1">
class="com.abc.activiti.listenner.xxxListenner">
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.JavaDelegateB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@39ca6dcd
xml流程：7f7aa2be-9a89-11e7-9d02-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@306a75c6
xml流程：7f7aa2be-9a89-11e7-9d02-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@342664daC类监听测试：
执行结果如下：
executionId：eebefb34-9a89-11e7-b1f2-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@26d8afc4
executionId：eebefb34-9a89-11e7-b1f2-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@38835b92
executionId：eebefb34-9a89-11e7-b1f2-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@21dcaa6e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;
@Service
public class JavaDelegateActivitiListenner implements JavaDelegate {
@Autowired
private ActivitiService activitiService;
@Override
public 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: null
at 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;
@Service
public class ActivitiListenner implements TaskListener, ExecutionListener {
/**
*
*/
private static final long serialVersionUID = -3759054058055401826L;
@Autowired
private ActivitiService activitiService;
@Override
public void notify(DelegateExecution execution) throws Exception {
System.out.println("xml流程：" + execution.getId() + " ActivitiListenner" + this.toString());
System.out.println("activitiService: " + activitiService.toString());
}
@Override
public 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@5de11ac2
2017-09-16 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: null
at 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]第二种尝试：expression配置实现监听
监听器配置：
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;
@Component
public class JavaExpressionActivitiListenner {
public void expression(DelegateExecution execution) throws Exception {
System.out.println("executionId：" + execution.getId() + " ActivitiListenner" + this.toString());
}
}
executionId：ddd3f07e-9a8d-11e7-9fc5-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaExpressionActivitiListenner@420a38c6
executionId：ddd3f07e-9a8d-11e7-9fc5-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaExpressionActivitiListenner@420a38c6
executionId：ddd3f07e-9a8d-11e7-9fc5-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaExpressionActivitiListenner@420a38c6B类监听测试：
测试结果：
xml流程：2175ef09-9a8e-11e7-9af4-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@2f68610c
xml流程：2175ef09-9a8e-11e7-9af4-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@2f68610c
xml流程：2175ef09-9a8e-11e7-9af4-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@2f68610cC类监听测试：
测试结果：
executionId：719dc30a-9a8d-11e7-9ac9-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@7374d21e
executionId：719dc30a-9a8d-11e7-9ac9-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@7374d21e
executionId：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@42e9857e
activitiService: com.abc.activiti.service.ActivitiService@2f9b021f
xml流程：2b882f40-9a91-11e7-9325-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@42e9857e
activitiService: com.abc.activiti.service.ActivitiService@2f9b021f
xml流程：2b882f40-9a91-11e7-9325-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@42e9857e
activitiService: com.abc.activiti.service.ActivitiService@2f9b021f第三种尝试：delegate expression配置实现监听
监听器配置：
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 ${javaExpressionActivitiListenner} did not resolve to an implementation of interface org.activiti.engine.delegate.ExecutionListener nor interface org.activiti.engine.delegate.JavaDelegate
at org.activiti.engine.impl.bpmn.listener.DelegateExpressionExecutionListener.notify(DelegateExpressionExecutionListener.java:57) ~[activiti-engine-5.20.0.jar:5.20.0]
at org.activiti.engine.impl.pvm.runtime.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:42) ~[activiti-engine-5.20.0.jar:na]xml流程：fcc6c8ba-9a95-11e7-826d-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@71425d05
activitiService: com.abc.activiti.service.ActivitiService@72a765d5
xml流程：fcc6c8ba-9a95-11e7-826d-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@71425d05
activitiService: com.abc.activiti.service.ActivitiService@72a765d5
xml流程：fcc6c8ba-9a95-11e7-826d-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.ActivitiListenner@71425d05
activitiService: com.abc.activiti.service.ActivitiService@72a765d5executionId：c96567e2-9a95-11e7-b7e3-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@6f660921 spring容器注入bean：com.abc.activiti.service.ActivitiService@1dc6b66a
executionId：c96567e2-9a95-11e7-b7e3-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@6f660921 spring容器注入bean：com.abc.activiti.service.ActivitiService@1dc6b66a
executionId：c96567e2-9a95-11e7-b7e3-b4b6761cb4ac ActivitiListennercom.abc.activiti.listenner.JavaDelegateActivitiListenner@6f660921 spring容器注入bean：com.abc.activiti.service.ActivitiService@1dc6b66a
通过delegate expression配置容器中的监听器时，仍然需要实现ExecutionListener或者JavaDelegate接口
总结：
1 通过javaClass加载指定类，这种硬编码的形式管理监听器，是将class字节码文件交由activitiEngine处理，每次需要的时候则由engine通过反射构建实例对象，spring无法管理；
2 通过delegate expression配置容器中的bean作为监听器，${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。