demo_ar_unity/Assets/FlutterUnityIntegration/UnityMessageManager.cs

using System;
using System.Collections.Generic;
using Newtonsoft.Json.Linq;
using UnityEngine;
using UnityEngine.SceneManagement;

namespace FlutterUnityIntegration
{
    public class MessageHandler
    {
        public int id;
        public string seq;

        public String name;
        private readonly JToken data;

        public static MessageHandler Deserialize(string message)
        {
            var m = JObject.Parse(message);
            var handler = new MessageHandler(
                m.GetValue("id").Value<int>(),
                m.GetValue("seq").Value<string>(),
                m.GetValue("name").Value<string>(),
                m.GetValue("data")
            );
            return handler;
        }

        public T getData<T>()
        {
            return data.Value<T>();
        }

        public MessageHandler(int id, string seq, string name, JToken data)
        {
            this.id = id;
            this.seq = seq;
            this.name = name;
            this.data = data;
        }

        public void send(object data)
        {
            var o = JObject.FromObject(new
            {
                id = id,
                seq = "end",
                name = name,
                data = data
            });
            UnityMessageManager.Instance.SendMessageToFlutter(UnityMessageManager.MessagePrefix + o.ToString());
        }
    }

    public class UnityMessage
    {
        public String name;
        public JObject data;
        public Action<object> callBack;
    }

    public class UnityMessageManager : SingletonMonoBehaviour<UnityMessageManager>
    {

        public const string MessagePrefix = "@UnityMessage@";
        private static int ID = 0;

        private static int generateId()
        {
            ID = ID + 1;
            return ID;
        }

        public delegate void MessageDelegate(string message);
        public event MessageDelegate OnMessage;

        public delegate void MessageHandlerDelegate(MessageHandler handler);
        public event MessageHandlerDelegate OnFlutterMessage;

        private readonly Dictionary<int, UnityMessage> waitCallbackMessageMap = new Dictionary<int, UnityMessage>();

        private void Start()
        {
            SceneManager.sceneLoaded += OnSceneLoaded;
        }

        void OnSceneLoaded(Scene scene, LoadSceneMode mode)
        {
            NativeAPI.OnSceneLoaded(scene, mode);

        }

        public void ShowHostMainWindow()
        {
            NativeAPI.ShowHostMainWindow();
        }

        public void UnloadMainWindow()
        {
            NativeAPI.UnloadMainWindow();
        }


        public void QuitUnityWindow()
        {
            NativeAPI.QuitUnityWindow();
        }


        public void SendMessageToFlutter(string message)
        {
            NativeAPI.SendMessageToFlutter(message);
        }

        public void SendMessageToFlutter(UnityMessage message)
        {
            var id = generateId();
            if (message.callBack != null)
            {
                waitCallbackMessageMap.Add(id, message);
            }

            var o = JObject.FromObject(new
            {
                id = id,
                seq = message.callBack != null ? "start" : "",
                name = message.name,
                data = message.data
            });
            UnityMessageManager.Instance.SendMessageToFlutter(MessagePrefix + o.ToString());
        }

        void onMessage(string message)
        {
            OnMessage?.Invoke(message);
        }

        void onFlutterMessage(string message)
        {
            if (message.StartsWith(MessagePrefix))
            {
                message = message.Replace(MessagePrefix, "");
            }
            else
            {
                return;
            }

            var handler = MessageHandler.Deserialize(message);
            if ("end".Equals(handler.seq))
            {
                // handle callback message
                if (!waitCallbackMessageMap.TryGetValue(handler.id, out var m)) return;
                waitCallbackMessageMap.Remove(handler.id);
                m.callBack?.Invoke(handler.getData<object>()); // todo
                return;
            }

            OnFlutterMessage?.Invoke(handler);
        }
    }
}