Activiti 自定义事件监听和邮件通知

骑猪看日落 2022-07-13 13:39 332阅读 0赞

# Activiti 自定义事件监听和邮件通知 #

参照Activiti官方文档[https://www.activiti.org/userguide/\#eventDispatcher][https_www.activiti.org_userguide_eventDispatcher]

首先，建立我们的需求。即当有任务创建、分配、完成时，邮件通知对应用户。

完成步骤如下：

1.  Activiti为我们提供了事件监听接口– ActivitiEventListener
2.  org.activiti.engine.delegate.event.ActivitiEventType提供了各种可以监听到的事件类型
3.  通过对应事件，获取有关联的用户，任务名称等。

public class OwnEventListener implements ActivitiEventListener { 
    
        @Override
        public void onEvent(ActivitiEvent event) {
            System.out.println("Event received: " + event.getType());
    
            if (event.getType() == ActivitiEventType.TASK_CREATED
                    || event.getType() == ActivitiEventType.TASK_ASSIGNED
                    || event.getType() == ActivitiEventType.TASK_COMPLETED) {
                ActivitiEntityEvent entityEvent = (ActivitiEntityEvent) event;
                TaskEntity taskEntity = (TaskEntity) entityEvent.getEntity();
                MailWrapper.getInstance().sendTaskMail(taskEntity.getOwner(), taskEntity.getAssignee(), taskEntity.getName(), event.getType());
            }
        }

> 最重要的一步就是强制将ActivitiEvent转换为其sub-interface(ActivitiEntityEvent)，再将获取的Entity强制转换为具体的Entity，最终获取相应信息。

在邮件发送模块，需要构建邮件模版，单例化邮件组件。

public class MailWrapper { 
        private final Logger log = LoggerFactory.getLogger(MailWrapper.class);
    
        @Autowired
        private MailSender mailSender;
    
        private MailWrapper() {
        Velocity.init(PropertiesUtil.readPropertiesInEnv("vm.properties"));
        }
    
        private static class WrapperSingleton { 
            static final MailWrapper mv = new MailWrapper();
        }
    
        public static MailWrapper getInstance() {
            return WrapperSingleton.mv;
        }
    
        public void sendTaskMail(String owner, String assignee, String taskName, ActivitiEventType eventType) {
            SimpleMailMessage msg = new SimpleMailMessage();
            String toEmailAddress = KeystoneClient.getInstance().findEmailByUserId(assignee);
            String ownerName = KeystoneClient.getInstance().findNameByUserId(owner);
            String assigneeName = KeystoneClient.getInstance().findNameByUserId(assignee);
    
            TaskMail tMail = new TaskMail(ownerName, assigneeName, taskName, eventType);
            VelocityContext model = new VelocityContext();
            model.put("task", tMail);
    
            Template template = Velocity.getTemplate("template/task_email.vm", "utf8");
    
            StringWriter w = new StringWriter();
            template.merge(model, w);
    
            msg.setSubject("hello world");
            msg.setTo(toEmailAddress);
            msg.setText(w.toString());
    
            try {
                mailSender.send(msg);
    
                log.info("mail has been sent to " + toEmailAddress);
            } catch (MailException e) {
                System.err.println(e.getMessage());
            }
        }
    }

在构建模版时，使用的是org.apache.velocity组件，其资源配置文件如下：

resource.loader = class
    class.resource.loader.description = Velocity Classpath Resource Loader
    class.resource.loader.class = org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader

告诉velocity，加载我们定义的模版文件时，使用classloader资源路径。当然，也可以配置物理路径，具体请参照官网，这里不加赘述。

[https_www.activiti.org_userguide_eventDispatcher]: https://www.activiti.org/userguide/#eventDispatcher