Spring 简明教程

Custom Events in Spring

编写和发布自定义事件需要进行很多步骤。遵循本章提供的指导编写、发布和处理 Custom Spring 事件。

There are number of steps to be taken to write and publish your own custom events. Follow the instructions given in this chapter to write, publish and handle 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.

下面是 CustomEvent.java 文件的内容

Here is the content of CustomEvent.java file

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";
   }
}

下面是 CustomEventPublisher.java 文件的内容

Following is the content of the CustomEventPublisher.java file

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);
   }
}

下面是 CustomEventHandler.java 文件的内容

Following is the content of the CustomEventHandler.java file

package com.tutorialspoint;

import org.springframework.context.ApplicationListener;

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

以下是 MainApp.java 文件的内容

Following is the content of the MainApp.java file

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

Following is the configuration file Beans.xml

<?xml version = "1.0" encoding = "UTF-8"?>

<beans xmlns = "http://www.springframework.org/schema/beans"
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation = "http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

   <bean id = "customEventHandler" class = "com.tutorialspoint.CustomEventHandler"/>
   <bean id = "customEventPublisher" class = "com.tutorialspoint.CustomEventPublisher"/>

</beans>

完成源文件和 Bean 配置文件创建后，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−

Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message −

y Custom Event
y Custom Event