最近在做公司的业务需要用到事件通知，比如启动成功打印日志，通知其他业务做相应的操作，就用到了Spring的事件通知机制。
Spring的事件通知本质上就是发布-订阅，即生产者-消费者；体现了观察者设计模式或者回调通知，那么Spring的事件是如何使用的？
有3要素：发布者-->事件-->监听者
Spring的事件必须依赖Spring容器，所以我在写demo的时候，需要Spring-boot-starter。
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<version>2.1.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.4</version>
</dependency>
</dependencies>
Spring的事件定义在ApplicationEvent类中，我们可以根据自己的需要自定义事件实体javabean。
@Data
public class TestSpringEvent extends ApplicationEvent {
/**
* Create a new ApplicationEvent.
*
* @param source the object on which the event initially occurred (never {@code null})
*/
public TestSpringEvent(Object source) {
super(source);
}
private Integer code;
private String message;
}
跟踪源码：
public abstract class ApplicationEvent extends EventObject {
/** use serialVersionUID from Spring 1.2 for interoperability. */
private static final long serialVersionUID = 7099057708183571937L;
/** System time when the event happened. */
private final long timestamp;
/**
* Create a new ApplicationEvent.
* @param source the object on which the event initially occurred (never {@code null})
*/
public ApplicationEvent(Object source) {
super(source);
this.timestamp = System.currentTimeMillis();
}
/**
* Return the system time in milliseconds when the event happened.
*/
public final long getTimestamp() {
return this.timestamp;
}
}
可以看出ApplicationEvent有属性时间戳，即事件的产生的时间，并有Object source属性，这个source是有特定意义的，官方的doc是The object on which the Event initially occurred.即发布事件的实体类。
进一步跟踪
public class EventObject implements java.io.Serializable {
private static final long serialVersionUID = 5516075349620653480L;
/**
* The object on which the Event initially occurred.
*/
protected transient Object source;
/**
* Constructs a prototypical Event.
*
* @param source The object on which the Event initially occurred.
* @exception IllegalArgumentException if source is null.
*/
public EventObject(Object source) {
if (source == null)
throw new IllegalArgumentException("null source");
this.source = source;
}
/**
* The object on which the Event initially occurred.
*
* @return The object on which the Event initially occurred.
*/
public Object getSource() {
return source;
}
/**
* Returns a String representation of this EventObject.
*
* @return A a String representation of this EventObject.
*/
public String toString() {
return getClass().getName() + "[source=" + source + "]";
}
}
定义了一个事件发生的不能序列化的对象
Spring事件的监听由ApplicationListener定义，我们写2个，来测试监听它执行的顺序
@Component
public class TestApplicationListener implements ApplicationListener<TestSpringEvent> {
//@Async
public void onApplicationEvent(TestSpringEvent event) {
System.out.println("code is:\t" + event.getCode() + ",\tmessage is:\t" + event.getMessage());
}
}
@Component
public class TestApplicationListenerCopy implements ApplicationListener<TestSpringEvent> {
//@Async
public void onApplicationEvent(TestSpringEvent event) {
System.out.println("2：code is:\t" + event.getCode() + ",\tmessage is:\t" + event.getMessage());
}
}
跟踪代码，可以看出ApplicationListener是一个函数式接口
@FunctionalInterface
public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {
/**
* Handle an application event.
* @param event the event to respond to
*/
void onApplicationEvent(E event);
}
Spring事件监听器的默认是单线程同步执行，异步执行需要加上Spring的@Async注解，或者自定义线程池实现.
也可以使用@EventListener
package com.feng.spring.listener;
import com.feng.spring.event.TestSpringEvent;
import org.springframework.context.event.EventListener;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Component;
@Component
public class TestApplicationListener2{
//@Async
@EventListener
public void onApplicationEvent(TestSpringEvent event) {
System.out.println("step2：code is:\t" + event.getCode() + ",\tmessage is:\t" + event.getMessage());
}
}
@Component
public class TestApplicationListener2Copy {
//@Async
@EventListener
public void onApplicationEvent(TestSpringEvent event) {
System.out.println("step3:code is:\t" + event.getCode() + ",\tmessage is:\t" + event.getMessage());
}
}
同理写2个实现
Spring的事件的发布定义在ApplicationEventPublisher类中，而ApplicationContext继承了这个类，因此ApplicationContext具有发布事件的能力，而且已经注入Spring的bean容器中，可直接获取。
public class SpringEventMain {
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
context.scan(SpringEventMain.class.getCanonicalName());
context.refresh();
TestSpringEvent testSpringEvent = new TestSpringEvent(new SpringEventMain());
testSpringEvent.setCode(10000);
testSpringEvent.setMessage("---------My Spring task event------------");
context.publishEvent(testSpringEvent);
}
}
注意：
new TestSpringEvent(new SpringEventMain())
这里的source是传入发布事件的实例对象。
运行后打印如下日志：
/software/jdk1.8.0_191/bin/java -javaagent:/software/ideaIde/lib/idea_rt.jar=36631:/software/ideaIde/bin -Dfile.encoding=UTF-8 -classpath /software/jdk1.8.0_191/jre/lib/charsets.jar:/software/jdk1.8.0_191/jre/lib/deploy.jar:/software/jdk1.8.0_191/jre/lib/ext/cldrdata.jar:/software/jdk1.8.0_191/jre/lib/ext/dnsns.jar:/software/jdk1.8.0_191/jre/lib/ext/jaccess.jar:/software/jdk1.8.0_191/jre/lib/ext/jfxrt.jar:/software/jdk1.8.0_191/jre/lib/ext/localedata.jar:/software/jdk1.8.0_191/jre/lib/ext/nashorn.jar:/software/jdk1.8.0_191/jre/lib/ext/sunec.jar:/software/jdk1.8.0_191/jre/lib/ext/sunjce_provider.jar:/software/jdk1.8.0_191/jre/lib/ext/sunpkcs11.jar:/software/jdk1.8.0_191/jre/lib/ext/zipfs.jar:/software/jdk1.8.0_191/jre/lib/javaws.jar:/software/jdk1.8.0_191/jre/lib/jce.jar:/software/jdk1.8.0_191/jre/lib/jfr.jar:/software/jdk1.8.0_191/jre/lib/jfxswt.jar:/software/jdk1.8.0_191/jre/lib/jsse.jar:/software/jdk1.8.0_191/jre/lib/management-agent.jar:/software/jdk1.8.0_191/jre/lib/plugin.jar:/software/jdk1.8.0_191/jre/lib/resources.jar:/software/jdk1.8.0_191/jre/lib/rt.jar:/home/huahua/IdeaProjects/feng/spring-event/target/classes:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-starter/2.1.1.RELEASE/spring-boot-starter-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot/2.1.1.RELEASE/spring-boot-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-context/5.1.3.RELEASE/spring-context-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-aop/5.1.3.RELEASE/spring-aop-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-beans/5.1.3.RELEASE/spring-beans-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-expression/5.1.3.RELEASE/spring-expression-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/2.1.1.RELEASE/spring-boot-autoconfigure-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-starter-logging/2.1.1.RELEASE/spring-boot-starter-logging-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar:/home/huahua/.m2/repository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar:/home/huahua/.m2/repository/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar:/home/huahua/.m2/repository/org/apache/logging/log4j/log4j-to-slf4j/2.11.1/log4j-to-slf4j-2.11.1.jar:/home/huahua/.m2/repository/org/apache/logging/log4j/log4j-api/2.11.1/log4j-api-2.11.1.jar:/home/huahua/.m2/repository/org/slf4j/jul-to-slf4j/1.7.25/jul-to-slf4j-1.7.25.jar:/home/huahua/.m2/repository/javax/annotation/javax.annotation-api/1.3.2/javax.annotation-api-1.3.2.jar:/home/huahua/.m2/repository/org/springframework/spring-core/5.1.3.RELEASE/spring-core-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-jcl/5.1.3.RELEASE/spring-jcl-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/yaml/snakeyaml/1.23/snakeyaml-1.23.jar:/home/huahua/.m2/repository/org/projectlombok/lombok/1.18.4/lombok-1.18.4.jar com.feng.spring.SpringEventMain
17:54:05.347 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/listener/TestApplicationListener.class]
17:54:05.352 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/listener/TestApplicationListener2.class]
17:54:05.353 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/listener/TestApplicationListener3.class]
17:54:05.353 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/listener/TestApplicationListenerCopy.class]
17:54:05.358 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@64b8f8f4
17:54:05.380 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
17:54:05.438 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
17:54:05.440 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
17:54:05.443 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
17:54:05.444 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
17:54:05.451 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testApplicationListener'
17:54:05.466 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testApplicationListener2'
17:54:05.470 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testApplicationListener3'
17:54:05.471 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testApplicationListenerCopy'
17:54:05.490 [main] DEBUG org.springframework.context.event.EventListenerMethodProcessor - 1 @EventListener methods processed on bean 'testApplicationListener2': {public void com.feng.spring.listener.TestApplicationListener2.onApplicationEvent(com.feng.spring.event.TestSpringEvent)=@org.springframework.context.event.EventListener(condition=, value=[], classes=[])}
17:54:05.491 [main] DEBUG org.springframework.context.event.EventListenerMethodProcessor - 1 @EventListener methods processed on bean 'testApplicationListener3': {public void com.feng.spring.listener.TestApplicationListener3.onApplicationEvent(com.feng.spring.event.TestSpringEvent)=@org.springframework.context.event.EventListener(condition=, value=[], classes=[])}
step2:code is: 10000, message is: ---------My Spring task event------------
step3:code is: 10000, message is: ---------My Spring task event------------
code is: 10000, message is: ---------My Spring task event------------
2：code is: 10000, message is: ---------My Spring task event------------
Process finished with exit code 0
说明Spring事件发布订阅成功。同时使用注解的监听比实现类监听先监听，如果我们需要监听的执行顺序怎么办？比如某些监听器先执行？
上面的示例，其实都是注解或者都是实现类，监听器是没有顺序的。如果我们要实现顺序监听呢？我么需要Ordered接口的实现，Spring提供的实现或者暴露的实现接口如下
如果需要执行顺序，Spring提供SmartApplicationListener与GenericApplicationListener可供选择。
其中GenericApplicationListener，Spring官方推荐我们提供adapter实现
/**
* Extended variant of the standard {@link ApplicationListener} interface,
* exposing further metadata such as the supported event and source type.
*
* <p>As of Spring Framework 4.2, this interface supersedes the Class-based
* {@link SmartApplicationListener} with full handling of generic event types.
*
* @author Stephane Nicoll
* @since 4.2
* @see SmartApplicationListener
* @see GenericApplicationListenerAdapter
*/
/**
* Extended variant of the standard {@link ApplicationListener} interface,
* exposing further metadata such as the supported event and source type.
*
* <p>As of Spring Framework 4.2, this interface supersedes the Class-based
* {@link SmartApplicationListener} with full handling of generic event types.
*
* @author Stephane Nicoll
* @since 4.2
* @see SmartApplicationListener
* @see GenericApplicationListenerAdapter
*/
public interface GenericApplicationListener extends ApplicationListener<ApplicationEvent>, Ordered {
/**
* Determine whether this listener actually supports the given event type.
* @param eventType the event type (never {@code null})
*/
boolean supportsEventType(ResolvableType eventType);
/**
* Determine whether this listener actually supports the given source type.
* <p>The default implementation always returns {@code true}.
* @param sourceType the source type, or {@code null} if no source
*/
default boolean supportsSourceType(@Nullable Class<?> sourceType) {
return true;
}
/**
* Determine this listener's order in a set of listeners for the same event.
* <p>The default implementation returns {@link #LOWEST_PRECEDENCE}.
*/
@Override
default int getOrder() {
return LOWEST_PRECEDENCE;
}
}
其实ApplicationListener在Spring中提供了很多默认实现，其中就有SmartApplicationListener，智能监听器。
下面来试试
*/
public interface SmartApplicationListener extends ApplicationListener<ApplicationEvent>, Ordered {
/**
* Determine whether this listener actually supports the given event type.
* @param eventType the event type (never {@code null})
*/
//supportsEventType与supportsSourceType同时true，监听器才会执行
//监听器支持的事件类型
boolean supportsEventType(Class<? extends ApplicationEvent> eventType);
/**
* Determine whether this listener actually supports the given source type.
* <p>The default implementation always returns {@code true}.
* @param sourceType the source type, or {@code null} if no source
*/
//supportsEventType与supportsSourceType同时true，监听器才会执行
//监听事件发布的类
default boolean supportsSourceType(@Nullable Class<?> sourceType) {
return true;
}
/**
* Determine this listener's order in a set of listeners for the same event.
* <p>The default implementation returns {@link #LOWEST_PRECEDENCE}.
*/
@Override
default int getOrder() {
return LOWEST_PRECEDENCE;
}
}
3个实现方法。支持的类型，支持的事件类，执行顺序
package com.feng.spring.listener;
import com.feng.spring.SpringEventMain;
import com.feng.spring.event.TestSpringEvent;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.event.SmartApplicationListener;
import org.springframework.stereotype.Component;
@Component
public class OrderedListener implements SmartApplicationListener {
public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
return eventType== TestSpringEvent.class;
}
public boolean supportsSourceType(Class<?> sourceType) {
return SpringEventMain.class==sourceType;
}
public int getOrder() {
return 5;
}
public void onApplicationEvent(ApplicationEvent event) {
System.out.println("my execute step is 555555555555555555555555555");
}
}
@Component
public class OrderedListenerCopy implements SmartApplicationListener {
public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
return eventType== TestSpringEvent.class;
}
public boolean supportsSourceType(Class<?> sourceType) {
return SpringEventMain.class==sourceType;
}
public int getOrder() {
return 6;
}
public void onApplicationEvent(ApplicationEvent event) {
System.out.println("my execute step is 6666666666666666666666666666");
}
}
同理写2个，执行结果如下：
/software/jdk1.8.0_191/bin/java -agentlib:jdwp=transport=dt_socket,address=127.0.0.1:46603,suspend=y,server=n -javaagent:/software/ideaIde/lib/rt/debugger-agent.jar -Dfile.encoding=UTF-8 -classpath /software/jdk1.8.0_191/jre/lib/charsets.jar:/software/jdk1.8.0_191/jre/lib/deploy.jar:/software/jdk1.8.0_191/jre/lib/ext/cldrdata.jar:/software/jdk1.8.0_191/jre/lib/ext/dnsns.jar:/software/jdk1.8.0_191/jre/lib/ext/jaccess.jar:/software/jdk1.8.0_191/jre/lib/ext/jfxrt.jar:/software/jdk1.8.0_191/jre/lib/ext/localedata.jar:/software/jdk1.8.0_191/jre/lib/ext/nashorn.jar:/software/jdk1.8.0_191/jre/lib/ext/sunec.jar:/software/jdk1.8.0_191/jre/lib/ext/sunjce_provider.jar:/software/jdk1.8.0_191/jre/lib/ext/sunpkcs11.jar:/software/jdk1.8.0_191/jre/lib/ext/zipfs.jar:/software/jdk1.8.0_191/jre/lib/javaws.jar:/software/jdk1.8.0_191/jre/lib/jce.jar:/software/jdk1.8.0_191/jre/lib/jfr.jar:/software/jdk1.8.0_191/jre/lib/jfxswt.jar:/software/jdk1.8.0_191/jre/lib/jsse.jar:/software/jdk1.8.0_191/jre/lib/management-agent.jar:/software/jdk1.8.0_191/jre/lib/plugin.jar:/software/jdk1.8.0_191/jre/lib/resources.jar:/software/jdk1.8.0_191/jre/lib/rt.jar:/home/huahua/IdeaProjects/feng/spring-event/target/classes:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-starter/2.1.1.RELEASE/spring-boot-starter-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot/2.1.1.RELEASE/spring-boot-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-context/5.1.3.RELEASE/spring-context-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-aop/5.1.3.RELEASE/spring-aop-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-beans/5.1.3.RELEASE/spring-beans-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-expression/5.1.3.RELEASE/spring-expression-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/2.1.1.RELEASE/spring-boot-autoconfigure-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-starter-logging/2.1.1.RELEASE/spring-boot-starter-logging-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar:/home/huahua/.m2/repository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar:/home/huahua/.m2/repository/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar:/home/huahua/.m2/repository/org/apache/logging/log4j/log4j-to-slf4j/2.11.1/log4j-to-slf4j-2.11.1.jar:/home/huahua/.m2/repository/org/apache/logging/log4j/log4j-api/2.11.1/log4j-api-2.11.1.jar:/home/huahua/.m2/repository/org/slf4j/jul-to-slf4j/1.7.25/jul-to-slf4j-1.7.25.jar:/home/huahua/.m2/repository/javax/annotation/javax.annotation-api/1.3.2/javax.annotation-api-1.3.2.jar:/home/huahua/.m2/repository/org/springframework/spring-core/5.1.3.RELEASE/spring-core-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-jcl/5.1.3.RELEASE/spring-jcl-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/yaml/snakeyaml/1.23/snakeyaml-1.23.jar:/home/huahua/.m2/repository/org/projectlombok/lombok/1.18.4/lombok-1.18.4.jar:/software/ideaIde/lib/idea_rt.jar com.feng.spring.SpringEventMain
Connected to the target VM, address: '127.0.0.1:46603', transport: 'socket'
18:37:51.002 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/listener/OrderedListener.class]
18:37:51.009 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/listener/OrderedListenerCopy.class]
18:37:51.017 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@37d31475
18:37:51.055 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
18:37:51.129 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
18:37:51.132 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
18:37:51.135 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
18:37:51.136 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
18:37:51.145 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'orderedListener'
18:37:51.154 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'orderedListenerCopy'
my execute step is 555555555555555555555555555
my execute step is 6666666666666666666666666666
Disconnected from the target VM, address: '127.0.0.1:46603', transport: 'socket'
Process finished with exit code 0
实现了顺序的监听。
Spring使用ThreadPoolTaskExecutor来执行异步任务，其实就是SchedulingTaskExecutor，使用@EnableAsync注解@Async注解实现异步监听事件的调用
我们来试试
package com.feng.spring.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import java.util.concurrent.Executor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
@Configuration
public class AsyncConfig {
@Bean
public Executor initExecutor(){
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
//定制线程名称，还可以定制线程group
executor.setThreadFactory(new ThreadFactory() {
private final AtomicInteger threadNumber = new AtomicInteger(1);
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(Thread.currentThread().getThreadGroup(), r,
"async-eventListener-" + threadNumber.getAndIncrement(),
0);
return t;
}
});
executor.setCorePoolSize(10);
executor.setMaxPoolSize(20);
executor.setKeepAliveSeconds(5);
executor.setQueueCapacity(100);
// executor.setRejectedExecutionHandler(null);
return executor;
}
}
@EnableAsync
@Component
public class TestApplicationListener implements ApplicationListener<TestSpringEvent> {
@Async
public void onApplicationEvent(TestSpringEvent event) {
System.out.println("code is:\t" + event.getCode() + ",\tmessage is:\t" + event.getMessage());
//通过线程group/名称区别
System.out.println(Thread.currentThread().getThreadGroup()+ "/" +Thread.currentThread().getName());
}
}
执行结果：
/software/jdk1.8.0_191/bin/java -agentlib:jdwp=transport=dt_socket,address=127.0.0.1:44287,suspend=y,server=n -javaagent:/software/ideaIde/lib/rt/debugger-agent.jar -Dfile.encoding=UTF-8 -classpath /software/jdk1.8.0_191/jre/lib/charsets.jar:/software/jdk1.8.0_191/jre/lib/deploy.jar:/software/jdk1.8.0_191/jre/lib/ext/cldrdata.jar:/software/jdk1.8.0_191/jre/lib/ext/dnsns.jar:/software/jdk1.8.0_191/jre/lib/ext/jaccess.jar:/software/jdk1.8.0_191/jre/lib/ext/jfxrt.jar:/software/jdk1.8.0_191/jre/lib/ext/localedata.jar:/software/jdk1.8.0_191/jre/lib/ext/nashorn.jar:/software/jdk1.8.0_191/jre/lib/ext/sunec.jar:/software/jdk1.8.0_191/jre/lib/ext/sunjce_provider.jar:/software/jdk1.8.0_191/jre/lib/ext/sunpkcs11.jar:/software/jdk1.8.0_191/jre/lib/ext/zipfs.jar:/software/jdk1.8.0_191/jre/lib/javaws.jar:/software/jdk1.8.0_191/jre/lib/jce.jar:/software/jdk1.8.0_191/jre/lib/jfr.jar:/software/jdk1.8.0_191/jre/lib/jfxswt.jar:/software/jdk1.8.0_191/jre/lib/jsse.jar:/software/jdk1.8.0_191/jre/lib/management-agent.jar:/software/jdk1.8.0_191/jre/lib/plugin.jar:/software/jdk1.8.0_191/jre/lib/resources.jar:/software/jdk1.8.0_191/jre/lib/rt.jar:/home/huahua/IdeaProjects/feng/spring-event/target/classes:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-starter/2.1.1.RELEASE/spring-boot-starter-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot/2.1.1.RELEASE/spring-boot-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-context/5.1.3.RELEASE/spring-context-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-aop/5.1.3.RELEASE/spring-aop-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-beans/5.1.3.RELEASE/spring-beans-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-expression/5.1.3.RELEASE/spring-expression-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/2.1.1.RELEASE/spring-boot-autoconfigure-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/boot/spring-boot-starter-logging/2.1.1.RELEASE/spring-boot-starter-logging-2.1.1.RELEASE.jar:/home/huahua/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar:/home/huahua/.m2/repository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar:/home/huahua/.m2/repository/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar:/home/huahua/.m2/repository/org/apache/logging/log4j/log4j-to-slf4j/2.11.1/log4j-to-slf4j-2.11.1.jar:/home/huahua/.m2/repository/org/apache/logging/log4j/log4j-api/2.11.1/log4j-api-2.11.1.jar:/home/huahua/.m2/repository/org/slf4j/jul-to-slf4j/1.7.25/jul-to-slf4j-1.7.25.jar:/home/huahua/.m2/repository/javax/annotation/javax.annotation-api/1.3.2/javax.annotation-api-1.3.2.jar:/home/huahua/.m2/repository/org/springframework/spring-core/5.1.3.RELEASE/spring-core-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/springframework/spring-jcl/5.1.3.RELEASE/spring-jcl-5.1.3.RELEASE.jar:/home/huahua/.m2/repository/org/yaml/snakeyaml/1.23/snakeyaml-1.23.jar:/home/huahua/.m2/repository/org/projectlombok/lombok/1.18.4/lombok-1.18.4.jar:/software/ideaIde/lib/idea_rt.jar com.feng.spring.SpringEventMain
Connected to the target VM, address: '127.0.0.1:44287', transport: 'socket'
19:08:24.692 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/config/AsyncConfig.class]
19:08:24.730 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/home/huahua/IdeaProjects/feng/spring-event/target/classes/com/feng/spring/listener/TestApplicationListener.class]
19:08:24.741 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@37d31475
19:08:24.782 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
19:08:25.091 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
19:08:25.094 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
19:08:25.099 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
19:08:25.100 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
19:08:25.106 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAsyncAnnotationProcessor'
19:08:25.109 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.scheduling.annotation.ProxyAsyncConfiguration'
19:08:25.252 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'asyncConfig'
19:08:25.261 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testApplicationListener'
19:08:25.299 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'initExecutor'
19:08:25.330 [main] INFO org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor - Initializing ExecutorService 'initExecutor'
code is: 10000, message is: ---------My Spring task event------------
java.lang.ThreadGroup[name=main,maxpri=10]/async-eventListener-1
看线程名称，已经异步执行了
[name=main,maxpri=10]/async-eventListener-1
Spring的事件通知demo已经完成，如果需要详细的Spring事件从发布到订阅的过程，需要跟踪Spring的ApplicationContext的publishEvent的过程，其实Spring的ApplicationContext的启动的过程中也定义了很详细的事件，使用intellij idea分析，如下：
Spring事件通知的本质：生产者-消费者，体现了设计模式的观察者模式。
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
