feat: plugin class is registered as a bean at startup (#2255)

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#### What type of PR is this?
/kind feature
/milestone 2.0
/area core
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/kind cleanup
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#### What this PR does / why we need it:
插件 plugin.yaml 中不用在写 pluginClass 属性，插件的生命周期类通过标注 `@Component` 注解在启动时通过 PluginApplicationContext 依赖注入并创建实例，这得益于每个插件都有一个单独的 PluginApplicationContext 插件启动时可以将PluginWrapper 放到 Context 以支撑 pluginClass 实例的创建
```yaml
apiVersion: plugin.halo.run/v1alpha1
kind: Plugin
metadata:
  # The name defines how the plugin is invoked,A unique name
  name: PluginTemplate
spec:
  pluginClass: run.halo.template.TemplatePlugin
```
现在只需要如下方式即可无需配置 pluginClass
```java
@Component
public class TemplatePlugin extends BasePlugin {}
```
#### Which issue(s) this PR fixes:

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Fixes #

#### Special notes for your reviewer:
/cc @halo-dev/sig-halo 
#### Does this PR introduce a user-facing change?

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src/main/java/run/halo/app/core/extension/Plugin.java

@@ -16,7 +16,6 @@ import org.pf4j.PluginState;
 import org.springframework.lang.NonNull;
 import run.halo.app.extension.AbstractExtension;
 import run.halo.app.extension.GVK;
-import run.halo.app.plugin.BasePlugin;
 
 /**
  * A custom resource for Plugin.
@@ -74,7 +73,8 @@ public class Plugin extends AbstractExtension {
          */
         private String requires = "*";
 
-        private String pluginClass = BasePlugin.class.getName();
+        @Deprecated
+        private String pluginClass;
 
         private Boolean enabled = false;
 

src/main/java/run/halo/app/core/extension/reconciler/PluginReconciler.java

@@ -173,7 +173,7 @@ public class PluginReconciler implements Reconciler {
 
     private void ensureSpecUpToDateWhenDevelopmentMode(PluginWrapper pluginWrapper,
         Plugin oldPlugin) {
-        if (!RuntimeMode.DEPLOYMENT.equals(pluginWrapper.getRuntimeMode())) {
+        if (RuntimeMode.DEPLOYMENT.equals(pluginWrapper.getRuntimeMode())) {
             return;
         }
         YamlPluginFinder yamlPluginFinder = new YamlPluginFinder();

src/main/java/run/halo/app/plugin/BasePlugin.java

@@ -35,7 +35,7 @@ public class BasePlugin extends Plugin {
         return applicationContext;
     }
 
-    public HaloPluginManager getPluginManager() {
+    private HaloPluginManager getPluginManager() {
         return (HaloPluginManager) getWrapper().getPluginManager();
     }
 }

src/main/java/run/halo/app/plugin/BasePluginFactory.java

@@ -0,0 +1,48 @@
+package run.halo.app.plugin;
+
+import java.util.Optional;
+import lombok.extern.slf4j.Slf4j;
+import org.pf4j.Plugin;
+import org.pf4j.PluginFactory;
+import org.pf4j.PluginWrapper;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+
+/**
+ * The default implementation for PluginFactory.
+ * <p>Get a {@link BasePlugin} instance from the {@link PluginApplicationContext}.</p>
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Slf4j
+public class BasePluginFactory implements PluginFactory {
+
+    @Override
+    public Plugin create(PluginWrapper pluginWrapper) {
+        return getPluginContext(pluginWrapper)
+            .map(context -> {
+                try {
+                    return context.getBean(BasePlugin.class);
+                } catch (NoSuchBeanDefinitionException e) {
+                    log.info(
+                        "No bean named 'basePlugin' found in the context create default instance");
+                    DefaultListableBeanFactory beanFactory =
+                        context.getDefaultListableBeanFactory();
+                    BasePlugin pluginInstance = new BasePlugin(pluginWrapper);
+                    beanFactory.registerSingleton(Plugin.class.getName(), pluginInstance);
+                    return pluginInstance;
+                }
+            })
+            .orElse(null);
+    }
+
+    private Optional<PluginApplicationContext> getPluginContext(PluginWrapper pluginWrapper) {
+        try {
+            return Optional.of(ExtensionContextRegistry.getInstance())
+                .map(registry -> registry.getByPluginId(pluginWrapper.getPluginId()));
+        } catch (IllegalArgumentException e) {
+            return Optional.empty();
+        }
+    }
+}

src/main/java/run/halo/app/plugin/HaloPluginManager.java

@@ -14,6 +14,7 @@ import org.pf4j.ExtensionFinder;
 import org.pf4j.PluginDependency;
 import org.pf4j.PluginDescriptor;
 import org.pf4j.PluginDescriptorFinder;
+import org.pf4j.PluginFactory;
 import org.pf4j.PluginRepository;
 import org.pf4j.PluginRuntimeException;
 import org.pf4j.PluginState;
@@ -80,6 +81,11 @@ public class HaloPluginManager extends DefaultPluginManager
         return pluginApplicationInitializer.getPluginApplicationContext(pluginId);
     }
 
+    @Override
+    protected PluginFactory createPluginFactory() {
+        return new BasePluginFactory();
+    }
+
     @Override
     public void afterPropertiesSet() {
         this.pluginApplicationInitializer = new PluginApplicationInitializer(this);

src/main/java/run/halo/app/plugin/PluginApplicationInitializer.java

@@ -66,6 +66,8 @@ public class PluginApplicationInitializer {
         AnnotationConfigUtils.registerAnnotationConfigProcessors(beanFactory);
         stopWatch.stop();
 
+        beanFactory.registerSingleton("pluginWrapper", haloPluginManager.getPlugin(pluginId));
+
         populateSettingFetcher(pluginId, beanFactory);
 
         log.debug("Total millis: {} ms -> {}", stopWatch.getTotalTimeMillis(),

src/main/java/run/halo/app/plugin/YamlPluginDescriptorFinder.java

@@ -50,7 +50,7 @@ public class YamlPluginDescriptorFinder implements PluginDescriptorFinder {
         DefaultPluginDescriptor defaultPluginDescriptor =
             new DefaultPluginDescriptor(pluginId,
                 spec.getDescription(),
-                spec.getPluginClass(),
+                BasePlugin.class.getName(),
                 spec.getVersion(),
                 spec.getRequires(),
                 spec.getAuthor(),

src/test/java/run/halo/app/core/extension/reconciler/PluginReconcilerTest.java

@@ -19,6 +19,7 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.pf4j.PluginState;
 import org.pf4j.PluginWrapper;
+import org.pf4j.RuntimeMode;
 import run.halo.app.core.extension.Plugin;
 import run.halo.app.extension.ExtensionClient;
 import run.halo.app.extension.controller.Reconciler;
@@ -53,6 +54,7 @@ class PluginReconcilerTest {
         pluginReconciler = new PluginReconciler(extensionClient, haloPluginManager, jsBundleRule);
 
         when(haloPluginManager.getPlugin(any())).thenReturn(pluginWrapper);
+        when(pluginWrapper.getRuntimeMode()).thenReturn(RuntimeMode.DEPLOYMENT);
         when(haloPluginManager.getUnresolvedPlugins()).thenReturn(List.of());
     }
 

src/test/java/run/halo/app/plugin/YamlPluginFinderTest.java

@@ -92,7 +92,7 @@ class YamlPluginFinderTest {
                             }
                         ],
                         "requires": ">=2.0.0",
-                        "pluginClass": "run.halo.app.plugin.BasePlugin",
+                        "pluginClass": null,
                         "enabled": false,
                         "extensionLocations": null,
                         settingName: null,