feat: support fixed plugin path for development mode (#2321)

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#### What type of PR is this?
/kind feature
/milestone 2.0
/area core
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#### What this PR does / why we need it:
目前插件开发模式允许配置项目目录，但必须配置到项目目录的上一级，并不友好
此 PR 提供了 fixedPluginPath 选项允许在开发模式时配置它为插件项目目录
在开发 gradle 插件时更易于通过配置此选项来加载插件
#### 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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```release-note
None
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src/main/java/run/halo/app/plugin/DefaultDevelopmentPluginRepository.java

@@ -0,0 +1,42 @@
+package run.halo.app.plugin;
+
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import org.pf4j.DevelopmentPluginRepository;
+import org.springframework.util.CollectionUtils;
+
+/**
+ * @author guqing
+ * @since 2.0.0
+ */
+public class DefaultDevelopmentPluginRepository extends DevelopmentPluginRepository {
+    private final List<Path> fixedPaths = new ArrayList<>();
+
+    public DefaultDevelopmentPluginRepository(Path... pluginsRoots) {
+        super(pluginsRoots);
+    }
+
+    public DefaultDevelopmentPluginRepository(List<Path> pluginsRoots) {
+        super(pluginsRoots);
+    }
+
+    public void addFixedPath(Path path) {
+        fixedPaths.add(path);
+    }
+
+    public void setFixedPaths(List<Path> paths) {
+        if (CollectionUtils.isEmpty(paths)) {
+            return;
+        }
+        fixedPaths.clear();
+        fixedPaths.addAll(paths);
+    }
+
+    @Override
+    public List<Path> getPluginPaths() {
+        List<Path> paths = new ArrayList<>(fixedPaths);
+        paths.addAll(super.getPluginPaths());
+        return paths;
+    }
+}

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

@@ -6,12 +6,16 @@ import java.nio.file.Path;
 import lombok.extern.slf4j.Slf4j;
 import org.pf4j.ClassLoadingStrategy;
 import org.pf4j.CompoundPluginLoader;
+import org.pf4j.CompoundPluginRepository;
+import org.pf4j.DefaultPluginRepository;
 import org.pf4j.DevelopmentPluginLoader;
 import org.pf4j.JarPluginLoader;
+import org.pf4j.JarPluginRepository;
 import org.pf4j.PluginClassLoader;
 import org.pf4j.PluginDescriptor;
 import org.pf4j.PluginLoader;
 import org.pf4j.PluginManager;
+import org.pf4j.PluginRepository;
 import org.pf4j.PluginStatusProvider;
 import org.pf4j.RuntimeMode;
 import org.springframework.beans.factory.annotation.Qualifier;
@@ -33,6 +37,7 @@ import org.springframework.web.reactive.accept.RequestedContentTypeResolver;
 public class PluginAutoConfiguration {
 
     private final PluginProperties pluginProperties;
+
     @Qualifier("webFluxContentTypeResolver")
     private final RequestedContentTypeResolver requestedContentTypeResolver;
 
@@ -126,11 +131,23 @@ public class PluginAutoConfiguration {
                     }
                     return super.createPluginStatusProvider();
                 }
+
+                @Override
+                protected PluginRepository createPluginRepository() {
+                    var developmentPluginRepository =
+                        new DefaultDevelopmentPluginRepository(getPluginsRoots());
+                    developmentPluginRepository
+                        .setFixedPaths(pluginProperties.getFixedPluginPath());
+                    return new CompoundPluginRepository()
+                        .add(developmentPluginRepository, this::isDevelopment)
+                        .add(new JarPluginRepository(getPluginsRoots()), this::isNotDevelopment)
+                        .add(new DefaultPluginRepository(getPluginsRoots()),
+                            this::isNotDevelopment);
+                }
             };
 
         pluginManager.setExactVersionAllowed(pluginProperties.isExactVersionAllowed());
         pluginManager.setSystemVersion(pluginProperties.getSystemVersion());
-
         return pluginManager;
     }
 }

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

@@ -0,0 +1,55 @@
+package run.halo.app.plugin;
+
+import java.nio.file.Path;
+import org.pf4j.PluginWrapper;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.context.ApplicationListener;
+import org.springframework.lang.NonNull;
+import org.springframework.stereotype.Component;
+import run.halo.app.core.extension.Plugin;
+import run.halo.app.extension.ExtensionClient;
+
+/**
+ * @author guqing
+ * @since 2.0.0
+ */
+@Component
+public class PluginDevelopmentInitializer implements ApplicationListener<ApplicationReadyEvent> {
+
+    private final HaloPluginManager haloPluginManager;
+
+    private final PluginProperties pluginProperties;
+
+    private final ExtensionClient extensionClient;
+
+    public PluginDevelopmentInitializer(HaloPluginManager haloPluginManager,
+        PluginProperties pluginProperties, ExtensionClient extensionClient) {
+        this.haloPluginManager = haloPluginManager;
+        this.pluginProperties = pluginProperties;
+        this.extensionClient = extensionClient;
+    }
+
+    @Override
+    public void onApplicationEvent(@NonNull ApplicationReadyEvent event) {
+        if (!haloPluginManager.isDevelopment()) {
+            return;
+        }
+        createFixedPluginIfNecessary(haloPluginManager);
+    }
+
+    private void createFixedPluginIfNecessary(HaloPluginManager pluginManager) {
+        for (Path path : pluginProperties.getFixedPluginPath()) {
+            String pluginId = pluginManager.loadPlugin(path);
+            PluginWrapper pluginWrapper = pluginManager.getPlugin(pluginId);
+            if (pluginWrapper == null) {
+                continue;
+            }
+            Plugin plugin = new YamlPluginFinder().find(pluginWrapper.getPluginPath());
+            extensionClient.fetch(Plugin.class, plugin.getMetadata().getName())
+                .ifPresentOrElse(persistent -> {
+                    plugin.getMetadata().setVersion(persistent.getMetadata().getVersion());
+                    extensionClient.update(plugin);
+                }, () -> extensionClient.create(plugin));
+        }
+    }
+}

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

@@ -1,5 +1,6 @@
 package run.halo.app.plugin;
 
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
 import lombok.Data;
@@ -22,6 +23,12 @@ public class PluginProperties {
      */
     private boolean autoStartPlugin = true;
 
+    /**
+     * The default plugin path is obtained through file scanning.
+     * In the development mode, you can specify the plugin path as the project directory.
+     */
+    private List<Path> fixedPluginPath = new ArrayList<>();
+
     /**
      * Plugins disabled by default.
      */

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

@@ -35,6 +35,13 @@ public class PluginRequestMappingHandlerMapping extends RequestMappingHandlerMap
     private final MultiValueMap<String, RequestMappingInfo> pluginMappingInfo =
         new LinkedMultiValueMap<>();
 
+    @Override
+    protected void initHandlerMethods() {
+        // Parent method will scan beans in the ApplicationContext
+        // detect and register handler methods.
+        // but this is superfluous for this class.
+    }
+
     /**
      * Register handler methods according to the plugin id and the controller(annotated
      * {@link Controller}) bean.

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

@@ -6,11 +6,9 @@ import com.fasterxml.jackson.databind.node.JsonNodeFactory;
 import java.util.Collection;
 import java.util.Map;
 import java.util.Optional;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 import org.apache.commons.lang3.StringUtils;
 import org.springframework.lang.NonNull;
-import org.springframework.lang.Nullable;
 import run.halo.app.core.extension.Plugin;
 import run.halo.app.extension.ConfigMap;
 import run.halo.app.extension.ExtensionClient;
@@ -19,17 +17,12 @@ import run.halo.app.infra.utils.JsonUtils;
 
 /**
  * <p>A value fetcher for pPlugin form configuration.</p>
- * <p>The method of obtaining values is lazy,only when it is used for the first time can the real
- * query value be obtained from {@link ConfigMap}.</p>
- * <p>It is thread safe.</p>
  *
  * @author guqing
  * @since 2.0.0
  */
 public class SettingFetcher {
 
-    private final AtomicReference<Map<String, JsonNode>> valueRef = new AtomicReference<>(null);
-
     private final ExtensionClient extensionClient;
 
     private final String pluginName;
@@ -40,13 +33,13 @@ public class SettingFetcher {
         this.pluginName = pluginName;
     }
 
-    @Nullable
+    @NonNull
-    public <T> T getGroupForObject(String group, Class<T> clazz) {
+    public <T> Optional<T> fetch(String group, Class<T> clazz) {
-        return convertValue(getInternal(group), clazz);
+        return Optional.ofNullable(convertValue(getInternal(group), clazz));
     }
 
     @NonNull
-    public JsonNode getGroup(String group) {
+    public JsonNode get(String group) {
         return getInternal(group);
     }
 
@@ -57,13 +50,11 @@ public class SettingFetcher {
      */
     @NonNull
     public Map<String, JsonNode> getValues() {
-        Map<String, JsonNode> values =
+        return Map.copyOf(getValuesInternal());
-            valueRef.updateAndGet(m -> m != null ? m : getValuesInternal());
-        return Map.copyOf(values);
     }
 
     private JsonNode getInternal(String group) {
-        return Optional.ofNullable(getValues().get(group))
+        return Optional.ofNullable(getValuesInternal().get(group))
             .orElse(JsonNodeFactory.instance.missingNode());
     }
 

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

@@ -64,29 +64,28 @@ class SettingFetcherTest {
         // The extensionClient will only be called once
         Map<String, JsonNode> callAgain = settingFetcher.getValues();
         assertThat(callAgain).isNotNull();
-        verify(extensionClient, times(1)).fetch(eq(ConfigMap.class), any());
     }
 
     @Test
     void getGroupForObject() throws JSONException {
-        Sns sns = settingFetcher.getGroupForObject("sns", Sns.class);
+        Optional<Sns> sns = settingFetcher.fetch("sns", Sns.class);
-        assertThat(sns).isNotNull();
+        assertThat(sns.isEmpty()).isFalse();
-        JSONAssert.assertEquals(getSns(), JsonUtils.objectToJson(sns), true);
+        JSONAssert.assertEquals(getSns(), JsonUtils.objectToJson(sns.get()), true);
 
-        Sns missing = settingFetcher.getGroupForObject("sns1", Sns.class);
+        Optional<Sns> missing = settingFetcher.fetch("sns1", Sns.class);
-        assertThat(missing).isNull();
+        assertThat(missing.isEmpty()).isTrue();
     }
 
     @Test
     void getGroup() {
-        JsonNode jsonNode = settingFetcher.getGroup("basic");
+        JsonNode jsonNode = settingFetcher.get("basic");
         assertThat(jsonNode).isNotNull();
         assertThat(jsonNode.isObject()).isTrue();
         assertThat(jsonNode.get("color").asText()).isEqualTo("red");
         assertThat(jsonNode.get("width").asInt()).isEqualTo(100);
 
         // missing key will return empty json node
-        JsonNode emptyNode = settingFetcher.getGroup("basic1");
+        JsonNode emptyNode = settingFetcher.get("basic1");
         assertThat(emptyNode.isEmpty()).isTrue();
     }