KeyboardInput单例模式

using UnityEngine;

namespace Client.Input
{
    public class KeyboardInput : MonoBehaviour
    {
        private static KeyboardInput _instance;

        public static KeyboardInput Instance
        {
            get
            {
                if (_instance) return _instance;
                _instance = FindObjectOfType<KeyboardInput>();
                if (_instance) return _instance;
                var go = new GameObject("KeyboardInput");
                _instance = go.AddComponent<KeyboardInput>();

                return _instance;
            }
        }

        public Vector2 Direction { get; private set; }

        private void Awake()
        {
            if (_instance is not null && _instance != this)
            {
                Destroy(gameObject);
            }
            else
            {
                _instance = this;
            }
        }

        private void Update()
        {
            if (UnityEngine.Input.GetKey(KeyCode.A))
            {
                Direction = new Vector2(-1, Direction.y);
            }

            if (UnityEngine.Input.GetKey(KeyCode.D))
            {
                Direction = new Vector2(1, Direction.y);
            }

            if (UnityEngine.Input.GetKey(KeyCode.W))
            {
                Direction = new Vector2(Direction.x, 1);
            }

            if (UnityEngine.Input.GetKey(KeyCode.S))
            {
                Direction = new Vector2(Direction.x, -1);
            }

            if (UnityEngine.Input.GetKey(KeyCode.A) && UnityEngine.Input.GetKey(KeyCode.D))
            {
                Direction = new Vector2(0, Direction.y);
            }

            if (!UnityEngine.Input.GetKey(KeyCode.A) && !UnityEngine.Input.GetKey(KeyCode.D))
            {
                Direction = new Vector2(0, Direction.y);
            }
            
            if (UnityEngine.Input.GetKey(KeyCode.W) && UnityEngine.Input.GetKey(KeyCode.S))
            {
                Direction = new Vector2(Direction.x, 0);
            }
            
            if (!UnityEngine.Input.GetKey(KeyCode.W) && !UnityEngine.Input.GetKey(KeyCode.S))
            {
                Direction = new Vector2(Direction.x, 0);
            }
            
        }
    }
}

GetKey可能并不完美，但是在后期供玩家修改键位时会有用。但也不推荐，现在我们可以使用Unity新的输入系统，这里不做过多介绍。