春のカスタムイベント

独自のカスタムイベントを作成して公開するには、いくつかの手順を実行する必要があります。この章の指示に従って、カスタムSpringイベントを作成、公開、および処理します。

Steps	Description
1	Create a project with a name SpringExample and create a package com.finddevguides 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.

*CustomEvent.java* ファイルの内容は次のとおりです。

package com.finddevguides;

import org.springframework.context.ApplicationEvent;

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

以下は CustomEventPublisher.java ファイルの内容です

package com.finddevguides;

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);
   }
}

以下は、 CustomEventHandler.java ファイルの内容です。

package com.finddevguides;

import org.springframework.context.ApplicationListener;

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

以下は MainApp.java ファイルの内容です

package com.finddevguides;

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();
   }
}

以下は設定ファイル Beans.xml です

<?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.finddevguides.CustomEventHandler"/>
   <bean id = "customEventPublisher" class = "com.finddevguides.CustomEventPublisher"/>

</beans>

ソースおよびBean構成ファイルの作成が完了したら、アプリケーションを実行しましょう。すべてがあなたのアプリケーションでうまくいけば、それは次のメッセージを印刷します-

y Custom Event
y Custom Event

Spring-custom-events-in-spring

春のカスタムイベント