春天的自定义事件

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📜 春天的自定义事件

📅 最后修改于: 2020-11-11 07:05:40 🧑 作者: Mango

编写和发布自己的自定义事件需要采取许多步骤。请按照本章中的说明编写，发布和处理Custom Spring Events。

Steps	Description
1	Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project. All the classes will be created under this package.
2	Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
3	Create an event class, CustomEvent by extending ApplicationEvent. This class must define a default constructor which should inherit constructor from ApplicationEvent class.
4	Once your event class is defined, you can publish it from any class, let us say EventClassPublisher which implements ApplicationEventPublisherAware. You will also need to declare this class in XML configuration file as a bean so that the container can identify the bean as an event publisher because it implements the ApplicationEventPublisherAware interface.
5	A published event can be handled in a class, let us say EventClassHandler which implements ApplicationListener interface and implements onApplicationEvent method for the custom event.
6	Create beans configuration file Beans.xml under the src folder and a MainApp class which will work as Spring application.
7	The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.

这是CustomEvent.java文件的内容

package com.tutorialspoint;

import org.springframework.context.ApplicationEvent;

public class CustomEvent extends ApplicationEvent{
   public CustomEvent(Object source) {
      super(source);
   }
   public String toString(){
      return "My Custom Event";
   }
}

以下是CustomEventPublisher.java文件的内容

package com.tutorialspoint;

import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;

public class CustomEventPublisher implements ApplicationEventPublisherAware {
   private ApplicationEventPublisher publisher;
   
   public void setApplicationEventPublisher (ApplicationEventPublisher publisher) {
      this.publisher = publisher;
   }
   public void publish() {
      CustomEvent ce = new CustomEvent(this);
      publisher.publishEvent(ce);
   }
}

以下是CustomEventHandler.java文件的内容

package com.tutorialspoint;

import org.springframework.context.ApplicationListener;

public class CustomEventHandler implements ApplicationListener {
   public void onApplicationEvent(CustomEvent event) {
      System.out.println(event.toString());
   }
}

以下是MainApp.java文件的内容

package com.tutorialspoint;

import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
   public static void main(String[] args) {
      ConfigurableApplicationContext context = 
         new ClassPathXmlApplicationContext("Beans.xml");
      
      CustomEventPublisher cvp = 
         (CustomEventPublisher) context.getBean("customEventPublisher");
      
      cvp.publish();  
      cvp.publish();
   }
}

以下是配置文件Beans.xml

完成创建源和Bean配置文件后，让我们运行该应用程序。如果您的应用程序一切正常，它将打印以下消息：

y Custom Event
y Custom Event