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#### What type of PR is this? /kind feature /area core /area plugin #### What this PR does / why we need it: This PR enhance usage of SharedEvent annotation to add support for publishing events among plugins. #### How to test? 1. Clone repository https://github.com/halo-dev/plugin-starter 2. Change build.gradle as following: ```gradle dependencies { implementation platform('run.halo.tools.platform:plugin:2.17.0-SNAPSHOT') ``` 3. Change StarterPlugin as following: ```java @Component public class StarterPlugin extends BasePlugin { private final ApplicationContext appContext; public StarterPlugin(PluginContext pluginContext, ApplicationContext appContext) { super(pluginContext); this.appContext = appContext; } @Override public void start() { appContext.publishEvent(new PostDeletedEvent(this, "fake-plugin")); } @Override public void stop() { } @EventListener(PostDeletedEvent.class) public void onApplicationEvent(PostDeletedEvent event) { System.out.println("Post deleted event received in plugin: " + event.getName()); } } ``` 4. Add a listener to Halo core ```java @EventListener(PostDeletedEvent.class) public void onApplicationEvent(PostDeletedEvent event) { System.out.println("Post deleted event received in core: " + event.getName()); } ``` 5. Build plugin and install plugin 6. Enable the plugin and see the result #### Does this PR introduce a user-facing change? ```release-note None ```
84 lines
2.1 KiB
Markdown
84 lines
2.1 KiB
Markdown
# 插件中如何发送共享事件（SharedEvent）
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在插件中，可以通过共享事件（SharedEvent）来发送消息。 共享事件是一种特殊的事件，它可以被核心和所有插件订阅。
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## 订阅共享事件
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目前，核心中已经提供了不少的共享事件，例如 `run.halo.app.event.post.PostPublishedEvent`、`run.halo.app.event.post.PostUpdatedEvent`
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，这些事件由核心发布，核心和插件均可订阅。请看下面的示例：
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```java
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@Component
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public class PostPublishedEventListener implements ApplicationListener<PostPublishedEvent> {
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@Override
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public void onApplicationEvent(PostPublishedEvent event) {
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// Do something
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}
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}
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```
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或者通过 `@EventListener` 注解实现，
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```java
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@Component
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public class PostPublishedEventListener {
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@EventListener
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// @Async // 如果需要异步处理，可以添加此注解
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public void onPostPublished(PostPublishedEvent event) {
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// Do something
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}
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}
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```
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> 需要注意的是，只有被 `@SharedEvent` 注解标记的事件才能够被其他插件或者核心订阅。
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## 发送共享事件
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在插件中，我们可以通过 `ApplicationEventPublisher` 来发送共享事件，请看下面的示例：
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```java
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@Service
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public class PostService {
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private final ApplicationEventPublisher eventPublisher;
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public PostService(ApplicationEventPublisher eventPublisher) {
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this.eventPublisher = eventPublisher;
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}
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public void publishPost(Post post) {
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// Do something
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eventPublisher.publishEvent(new PostPublishedEvent(post));
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}
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}
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```
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## 创建共享事件
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在插件中，我们可以创建自定义的共享事件，供其他插件订阅，示例如下：
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```java
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@SharedEvent
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public class MySharedEvent extends ApplicationEvent {
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public MySharedEvent(Object source) {
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super(source);
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}
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}
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```
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> 需要注意的是：
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> 1. 共享事件必须继承 `ApplicationEvent`。
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> 2. 共享事件必须被 `@SharedEvent` 注解标记。
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> 3. 如果想要被其他插件订阅，则需要将该事件类发布到 Maven 仓库中，供其他插件引用。
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