Spring自定义事件

也有将要采取的编写和发布自己的自定义事件的步骤。按照本章编写，发布和处理自定义Spring 动作说明。

步骤	描述
1	Create a project with a name SpringExample and create a package com.manongjc 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 sayEventClassPublisher 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 implementsApplicationListener 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.

这里是CustomEvent.java文件的内容：

package com.manongjc;

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.manongjc;

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.manongjc;

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：

package com.manongjc;

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文件：

<?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.manongjc.CustomEventHandler"/>

   <bean id="customEventPublisher" 
      class="com.manongjc.CustomEventPublisher"/>

</beans>

创建源程序和bean配置文件完成后，让我们运行应用程序。如果一切顺利，这将打印以下信息：

My Custom Event
My Custom Event