Find plugin instance when loaded through PaperPluginClassLoader

inventoryaccess/inventory-access/src/main/java/xyz/xenondevs/inventoryaccess/util/ReflectionRegistry.java

@@ -17,10 +17,12 @@ public class ReflectionRegistry {
     
     // Classes
     public static final Class<?> PLUGIN_CLASS_LOADER_CLASS = getBukkitClass("plugin.java.PluginClassLoader");
+    public static final Class<?> PAPER_PLUGIN_CLASS_LOADER_CLASS = getClassOrNull("io.papermc.paper.plugin.entrypoint.classloader.PaperPluginClassLoader");
     public static final Class<?> CB_CRAFT_META_SKULL_CLASS = getCBClass("inventory.CraftMetaSkull");
     public static final Class<?> CB_CRAFT_META_ITEM_CLASS = getCBClass("inventory.CraftMetaItem");
     
     // Methods
+    public static final Method PAPER_PLUGIN_CLASS_LOADER_GET_LOADED_JAVA_PLUGIN_METHOD;
     public static final Method CB_CRAFT_META_SKULL_SET_PROFILE_METHOD = getMethod(CB_CRAFT_META_SKULL_CLASS, true, "setProfile", GameProfile.class);
     
     // Fields
@@ -28,4 +30,10 @@ public class ReflectionRegistry {
     public static final Field CB_CRAFT_META_ITEM_DISPLAY_NAME_FIELD = getField(CB_CRAFT_META_ITEM_CLASS, true, "displayName");
     public static final Field CB_CRAFT_META_ITEM_LORE_FIELD = getField(CB_CRAFT_META_ITEM_CLASS, true, "lore");
     
+    static {
+        Method getPlugin = getMethodOrNull(PAPER_PLUGIN_CLASS_LOADER_CLASS, false, "getLoadedJavaPlugin");
+        if (getPlugin == null) getPlugin = getMethodOrNull(PAPER_PLUGIN_CLASS_LOADER_CLASS, false, "getPlugin");
+        PAPER_PLUGIN_CLASS_LOADER_GET_LOADED_JAVA_PLUGIN_METHOD = getPlugin;
+    }
+    
 }

inventoryaccess/inventory-access/src/main/java/xyz/xenondevs/inventoryaccess/util/ReflectionUtils.java

@@ -5,7 +5,6 @@ import xyz.xenondevs.inventoryaccess.version.InventoryAccessRevision;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
-import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 
 @SuppressWarnings({"unchecked", "unused"})
@@ -26,11 +25,9 @@ public class ReflectionUtils {
     public static <T> Class<T> getImplClass(String path) {
         try {
             return (Class<T>) Class.forName("xyz.xenondevs.inventoryaccess." + InventoryAccessRevision.REQUIRED_REVISION.getPackageName() + "." + path);
-        } catch (ClassNotFoundException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
-        
-        return null;
     }
     
     public static <T> Class<T> getBukkitClass(String path) {
@@ -44,11 +41,17 @@ public class ReflectionUtils {
     public static <T> Class<T> getClass(String path) {
         try {
             return (Class<T>) Class.forName(path);
-        } catch (ClassNotFoundException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
+        }
+    }
+    
+    public static <T> Class<T> getClassOrNull(String path) {
+        try {
+            return (Class<T>) Class.forName(path);
+        } catch (Throwable t) {
+            return null;
         }
-        
-        return null;
     }
     
     public static Field getField(Class<?> clazz, boolean declared, String name) {
@@ -56,11 +59,9 @@ public class ReflectionUtils {
             Field field = declared ? clazz.getDeclaredField(name) : clazz.getField(name);
             if (declared) field.setAccessible(true);
             return field;
-        } catch (NoSuchFieldException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
-        
-        return null;
     }
     
     public static <T> Constructor<T> getConstructor(Class<T> clazz, boolean declared, Class<?>... parameterTypes) {
@@ -68,31 +69,25 @@ public class ReflectionUtils {
             Constructor<T> constructor = declared ? clazz.getDeclaredConstructor(parameterTypes) : clazz.getConstructor(parameterTypes);
             if (declared) constructor.setAccessible(true);
             return constructor;
-        } catch (NoSuchMethodException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
-        
-        return null;
     }
     
     public static <T> T constructEmpty(Class<?> clazz) {
         try {
             return (T) getConstructor(clazz, true).newInstance();
-        } catch (ReflectiveOperationException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
-        
-        return null;
     }
     
     public static <T> T construct(Constructor<T> constructor, Object... args) {
         try {
             return constructor.newInstance(args);
-        } catch (ReflectiveOperationException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
-        
-        return null;
     }
     
     public static Method getMethod(Class<?> clazz, boolean declared, String name, Class<?>... parameterTypes) {
@@ -100,28 +95,34 @@ public class ReflectionUtils {
             Method method = declared ? clazz.getDeclaredMethod(name, parameterTypes) : clazz.getMethod(name, parameterTypes);
             if (declared) method.setAccessible(true);
             return method;
-        } catch (NoSuchMethodException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
+        }
+    }
+    
+    public static Method getMethodOrNull(Class<?> clazz, boolean declared, String name, Class<?>... parameterTypes) {
+        try {
+            Method method = declared ? clazz.getDeclaredMethod(name, parameterTypes) : clazz.getMethod(name, parameterTypes);
+            if (declared) method.setAccessible(true);
+            return method;
+        } catch (Throwable t) {
+            return null;
         }
-        
-        return null;
     }
     
     public static <T> T invokeMethod(Method method, Object obj, Object... args) {
         try {
             return (T) method.invoke(obj, args);
-        } catch (IllegalAccessException | InvocationTargetException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
-        
-        return null;
     }
     
     public static void setFieldValue(Field field, Object obj, Object value) {
         try {
             field.set(obj, value);
-        } catch (IllegalAccessException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
     }
     
@@ -129,11 +130,9 @@ public class ReflectionUtils {
     public static <T> T getFieldValue(Field field, Object obj) {
         try {
             return (T) field.get(obj);
-        } catch (IllegalAccessException e) {
+        } catch (Throwable t) {
-            e.printStackTrace();
+            throw new RuntimeException(t);
         }
-        
-        return null;
     }
     
 }

invui-core/src/main/java/xyz/xenondevs/invui/InvUI.java

@@ -6,12 +6,15 @@ import org.bukkit.event.Listener;
 import org.bukkit.event.server.PluginDisableEvent;
 import org.bukkit.plugin.Plugin;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import xyz.xenondevs.inventoryaccess.util.ReflectionRegistry;
 import xyz.xenondevs.inventoryaccess.util.ReflectionUtils;
 
 import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Logger;
 
+import static xyz.xenondevs.inventoryaccess.util.ReflectionRegistry.PAPER_PLUGIN_CLASS_LOADER_GET_LOADED_JAVA_PLUGIN_METHOD;
 import static xyz.xenondevs.inventoryaccess.util.ReflectionRegistry.PLUGIN_CLASS_LOADER_PLUGIN_FIELD;
 
 public class InvUI implements Listener {
@@ -30,14 +33,27 @@ public class InvUI implements Listener {
     
     public @NotNull Plugin getPlugin() {
         if (plugin == null) {
-            // get plugin from class loader if it wasn't set manually
+            plugin = tryFindPlugin();
-            plugin = ReflectionUtils.getFieldValue(PLUGIN_CLASS_LOADER_PLUGIN_FIELD, getClass().getClassLoader());
+            
-            Bukkit.getPluginManager().registerEvents(this, plugin);
+            if (plugin == null)
+                throw new IllegalStateException("Plugin is not set. Set it using InvUI.getInstance().setPlugin(plugin);");
         }
         
         return plugin;
     }
     
+    private @Nullable Plugin tryFindPlugin() {
+        ClassLoader loader = getClass().getClassLoader();
+        
+        if (ReflectionRegistry.PLUGIN_CLASS_LOADER_CLASS.isInstance(loader)) {
+            return ReflectionUtils.getFieldValue(PLUGIN_CLASS_LOADER_PLUGIN_FIELD, loader);
+        } else if (ReflectionRegistry.PAPER_PLUGIN_CLASS_LOADER_CLASS.isInstance(loader)) {
+            return ReflectionUtils.invokeMethod(PAPER_PLUGIN_CLASS_LOADER_GET_LOADED_JAVA_PLUGIN_METHOD, loader);
+        }
+        
+        return null;
+    }
+    
     public void setPlugin(@NotNull Plugin plugin) {
         if (this.plugin != null)
             throw new IllegalStateException("Plugin is already set");