- Declared ObjectSerializer interface for json/msgpack encoding/decoding

- Implemented JsonSerializer annotation for better json handling

Author: sacOO7

lib/src/main/java/io/ably/lib/object/serialization/ObjectJsonSerializer.java

@@ -0,0 +1,33 @@
+package io.ably.lib.object.serialization;
+
+import com.google.gson.*;
+import io.ably.lib.util.Log;
+
+import java.lang.reflect.Type;
+
+public class ObjectJsonSerializer implements JsonSerializer<Object[]>, JsonDeserializer<Object[]> {
+    private static final String TAG = ObjectJsonSerializer.class.getName();
+
+    @Override
+    public Object[] deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+        ObjectSerializer serializer = ObjectSerializer.tryGet();
+        if (serializer == null) {
+            Log.w(TAG, "Skipping 'state' field json deserialization because ObjectsSerializer not found.");
+            return null;
+        }
+        if (!json.isJsonArray()) {
+            throw new JsonParseException("Expected a JSON array for 'state' field, but got: " + json);
+        }
+        return serializer.readFromJsonArray(json.getAsJsonArray());
+    }
+
+    @Override
+    public JsonElement serialize(Object[] src, Type typeOfSrc, JsonSerializationContext context) {
+        ObjectSerializer serializer = ObjectSerializer.tryGet();
+        if (serializer == null) {
+            Log.w(TAG, "Skipping 'state' field json serialization because ObjectsSerializer not found.");
+            return JsonNull.INSTANCE;
+        }
+        return serializer.asJsonArray(src);
+    }
+}

lib/src/main/java/io/ably/lib/object/serialization/ObjectSerializer.java

@@ -0,0 +1,98 @@
+package io.ably.lib.object.serialization;
+
+import com.google.gson.JsonArray;
+import io.ably.lib.util.Log;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.msgpack.core.MessagePacker;
+import org.msgpack.core.MessageUnpacker;
+
+import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+
+/**
+ * Serializer interface for converting between objects and their MessagePack or JSON representations.
+ */
+public interface ObjectSerializer {
+
+    /**
+     * Reads a MessagePack array from the given unpacker and deserializes it into an Object array.
+     *
+     * @param unpacker the MessageUnpacker to read from
+     * @return the deserialized Object array
+     * @throws IOException if an I/O error occurs during unpacking
+     */
+    @NotNull
+    Object[] readMsgpackArray(@NotNull MessageUnpacker unpacker) throws IOException;
+
+    /**
+     * Serializes the given Object array as a MessagePack array using the provided packer.
+     *
+     * @param objects the Object array to serialize
+     * @param packer the MessagePacker to write to
+     * @throws IOException if an I/O error occurs during packing
+     */
+    void writeMsgpackArray(@NotNull Object[] objects, @NotNull MessagePacker packer) throws IOException;
+
+    /**
+     * Reads a JSON array from the given {@link JsonArray} and deserializes it into an Object array.
+     *
+     * @param json the {@link JsonArray} representing the array to deserialize
+     * @return the deserialized Object array
+     */
+    @NotNull
+    Object[] readFromJsonArray(@NotNull JsonArray json);
+
+    /**
+     * Serializes the given Object array as a JSON array.
+     *
+     * @param objects the Object array to serialize
+     * @return the resulting JsonArray
+     */
+    @NotNull
+    JsonArray asJsonArray(@NotNull Object[] objects);
+
+    /**
+     * Returns the lazily-initialized, process-wide {@link ObjectSerializer} singleton, reflectively
+     * loaded from the LiveObjects plugin on the classpath. Returns {@code null} if the plugin is not
+     * present; the lookup is retried on subsequent calls until it succeeds.
+     *
+     * @return the shared {@link ObjectSerializer} instance, or {@code null} if the plugin is unavailable.
+     */
+    @Nullable
+    static ObjectSerializer tryGet() {
+        return Holder.getSerializer();
+    }
+
+    /**
+     * Holds the lazily-initialized {@link ObjectSerializer} singleton. Interfaces cannot declare
+     * mutable static fields, so the cache lives here while {@link #tryGet()} delegates to it.
+     */
+    final class Holder {
+        private static final String TAG = ObjectSerializer.Holder.class.getName();
+        private static final String IMPLEMENTATION_CLASS = "io.ably.lib.object.serialization.DefaultObjectsSerializer";
+        private static volatile ObjectSerializer objectsSerializer;
+
+        private Holder() {}
+
+        @Nullable
+        static ObjectSerializer getSerializer() {
+            if (objectsSerializer == null) {
+                synchronized (Holder.class) {
+                    if (objectsSerializer == null) { // Double-Checked Locking (DCL)
+                        try {
+                            Class<?> serializerClass = Class.forName(IMPLEMENTATION_CLASS);
+                            objectsSerializer = (ObjectSerializer) serializerClass.getDeclaredConstructor().newInstance();
+                        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException |
+                                 NoSuchMethodException |
+                                 InvocationTargetException e) {
+                            Log.w(TAG, "Failed to init ObjectsSerializer, LiveObjects plugin not included in the classpath", e);
+                            return null;
+                        }
+                    }
+                }
+            }
+            return objectsSerializer;
+        }
+    }
+}