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mercyblitzmercyblitz
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Polish Stage 7 Lesson 2
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‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/pom.xml

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<name>「一入 Java 深似海 」系列 :: 第七期</name>
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<modules>
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<module>stage-7-lesson-1</module>
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<module>stage-7-lesson-2</module>
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</modules>
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</project>

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<parent>
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<artifactId>stage-7</artifactId>
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<groupId>com.segmentfault</groupId>
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<version>1.0-SNAPSHOT</version>
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</parent>
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<modelVersion>4.0.0</modelVersion>
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<artifactId>stage-7-lesson-2</artifactId>
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<name>「一入 Java 深似海 」系列 :: 第七期 :: 第二节</name>
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</project>

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/customization/IdPropertyEditor.java

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package com.segmentfault.deep.in.java.beans.customization;
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import java.beans.PropertyEditor;
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import java.beans.PropertyEditorSupport;
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import static com.segmentfault.deep.in.java.beans.properties.Person.isNumeric;
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/**
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* Person id 属性编辑器
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* Id String -> Long
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*/
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public class IdPropertyEditor extends PropertyEditorSupport {
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public void setAsText(String text) {
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if (isNumeric(text)) {
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setValue(Long.valueOf(text));
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}
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}
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/**
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* 覆盖父类方法
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*
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* @return
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*/
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@Override
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public Long getValue() {
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return (Long) super.getValue();
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/customization/PersonBeanCustomization.java

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package com.segmentfault.deep.in.java.beans.customization;
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import com.segmentfault.deep.in.java.beans.properties.Person;
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import java.beans.BeanInfo;
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import java.beans.IntrospectionException;
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import java.beans.Introspector;
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import java.beans.PropertyEditor;
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import java.util.Date;
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import java.util.stream.Stream;
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public class PersonBeanCustomization {
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public static void main(String[] args) throws IntrospectionException {
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// 排除 java.lang.Object.class 类定义的干扰
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BeanInfo beanInfo = Introspector.getBeanInfo(Person.class, Object.class);
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Person personBean = new Person();
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Stream.of(beanInfo.getPropertyDescriptors())
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.filter(propertyDescriptor -> "id".equals(propertyDescriptor.getName())) // 过滤 "id" 属性
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.findFirst()
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.ifPresent(idPropertyDescriptor -> {
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// 为 "id" 属性描述注册属性修改器
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idPropertyDescriptor.setPropertyEditorClass(IdPropertyEditor.class);
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PropertyEditor propertyEditor = idPropertyDescriptor.createPropertyEditor(personBean);
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// 添加属性变化事件
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propertyEditor.addPropertyChangeListener(event -> {
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personBean.setId((Long) propertyEditor.getValue());
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});
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// 通过 setAsText(String) 方法模拟 <property name="id">1</property>
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propertyEditor.setAsText("1");
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}
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);
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Stream.of(beanInfo.getPropertyDescriptors())
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.filter(propertyDescriptor -> "updateTime".equals(propertyDescriptor.getName())) // 过滤 "updateTime" 属性
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.findFirst()
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.ifPresent(propertyDescriptor -> {
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// 为 "updateTime" 属性描述注册属性修改器
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propertyDescriptor.setPropertyEditorClass(UpdateTimePropertyEditor.class);
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PropertyEditor propertyEditor = propertyDescriptor.createPropertyEditor(personBean);
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// 添加属性变化事件
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propertyEditor.addPropertyChangeListener(event -> {
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personBean.setUpdateTime((Date) propertyEditor.getValue());
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});
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// 通过 setAsText(String) 方法模拟 <property name="updateTime">2019-10-23 23:16:00</property>
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propertyEditor.setAsText("2019-10-23 23:16:00");
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}
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);
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System.out.println("当前 person = " + personBean);
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/customization/PersonBeanDemo.java

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package com.segmentfault.deep.in.java.beans.customization;
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public class PersonBeanDemo {
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public static void main(String[] args) {
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/**
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* <bean id="person" class="com.segmentfault.deep.in.java.beans.properties.Person" >
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* <property name="id">1</property> <!-- id 类型是 Long (String to Long) -->
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* <property name="name">小马哥</property> <!-- name 类型是 String -->
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* <property name="age">34</property> <!-- age 类型是 int (String to int) -->
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* </bean>
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*/
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/customization/UpdateTimePropertyEditor.java

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package com.segmentfault.deep.in.java.beans.customization;
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import java.beans.PropertyEditorSupport;
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import java.text.ParseException;
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import java.text.SimpleDateFormat;
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public class UpdateTimePropertyEditor extends PropertyEditorSupport {
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public void setAsText(String text) {
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SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
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try {
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setValue(format.parse(text));
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} catch (ParseException e) {
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e.printStackTrace();
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}
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/event/ApplicationEvent.java

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package com.segmentfault.deep.in.java.beans.event;
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import java.util.EventObject;
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public class ApplicationEvent extends EventObject {
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private final long timestamp;
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/**
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* Constructs a prototypical Event.
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*
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* @param source the object on which the Event initially occurred
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* @throws IllegalArgumentException if source is null
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*/
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public ApplicationEvent(Object source) {
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super(source);
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this.timestamp = System.currentTimeMillis();
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}
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public long getTimestamp() {
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return timestamp;
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}
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@Override
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public String toString() {
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return "ApplicationEvent{" +
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"timestamp=" + timestamp +
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", source=" + source +
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'}';
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/event/ApplicationEventListener.java

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package com.segmentfault.deep.in.java.beans.event;
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import java.util.EventListener;
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/**
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* 应用事件监听器
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*
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* @see EventListener
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* @param <E> ApplicationEvent 以及它的子类型
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*/
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public interface ApplicationEventListener<E extends ApplicationEvent> extends EventListener {
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/**
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* 处理事件
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* @param event
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*/
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void onEvent(E event);
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/event/ApplicationEventListenerRegistry.java

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package com.segmentfault.deep.in.java.beans.event;
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public interface ApplicationEventListenerRegistry {
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void addApplicationEventListener(ApplicationEventListener<?> listener);
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void removeApplicationEventListener(ApplicationEventListener<?> listener);
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ApplicationEventListener[] getApplicationEventListeners();
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ApplicationEventListener[] getApplicationEventListeners(Class<? extends ApplicationEvent> eventType);
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-7/stage-7-lesson-2/src/main/java/com/segmentfault/deep/in/java/beans/event/ApplicationEventMulticaster.java

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package com.segmentfault.deep.in.java.beans.event;
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/**
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* {@link ApplicationEvent} 广播器
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*/
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public class ApplicationEventMulticaster {
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private final ApplicationEventListenerRegistry registry;
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public ApplicationEventMulticaster() {
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this.registry = new SimpleApplicationEventListenerRegistry();
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}
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public ApplicationEventMulticaster(ApplicationEventListenerRegistry registry) {
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this.registry = registry;
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}
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public void addApplicationEventListener(ApplicationEventListener<?> listener) {
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registry.addApplicationEventListener(listener);
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}
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public void removeApplicationEventListener(ApplicationEventListener<?> listener) {
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registry.removeApplicationEventListener(listener);
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}
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public ApplicationEventListener[] getApplicationEventListeners() {
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return registry.getApplicationEventListeners();
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}
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public ApplicationEventListener[] getApplicationEventListeners(Class<? extends ApplicationEvent> eventType) {
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return registry.getApplicationEventListeners(eventType);
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}
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public void multicastEvent(ApplicationEvent event) {
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// 逐一传递
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Class<? extends ApplicationEvent> eventType = event.getClass();
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for (ApplicationEventListener listener : getApplicationEventListeners(eventType)) {
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listener.onEvent(event);
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}
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}
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public static void main(String[] args) {
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// displaySimpleEvent();
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displayGenericEvent();
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}
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private static void displayGenericEvent() {
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ApplicationEventMulticaster multicaster =
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new ApplicationEventMulticaster(new GenericApplicationEventListenerRegistry());
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multicaster.addApplicationEventListener(new MyEventListener());
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multicaster.addApplicationEventListener(new MyEventListener2());
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// 传播的是 ApplicationEvent，MyEventListener 需要 MyEvent 类型，属于前者子类
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multicaster.multicastEvent(new MyEvent("2019"));
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}
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private static void displaySimpleEvent() {
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ApplicationEventMulticaster multicaster = new ApplicationEventMulticaster();
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// 注册一个事件监听器
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multicaster.addApplicationEventListener(event -> {
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System.out.println("处理事件-1 : " + event);
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});
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multicaster.addApplicationEventListener(event -> {
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System.out.println("处理事件-2 : " + event);
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});
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multicaster.addApplicationEventListener(event -> {
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System.out.println("处理事件-3 : " + event);
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});
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// 广播事件
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multicaster.multicastEvent(new ApplicationEvent("Hello,World"));
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}
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}

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