Unity通过Attribute代替getComponent获取组件

每次用Unity做了一个界面，写代码时都要为了获取UI的组件或者子物体而写一堆的
Transform.FindChild 和 getComponent 这么做虽然没什么错，但是写出来的代码
太难看了，冗余代码也多，实在受不了了，所以写了一个工具类，通过C#的Attribute
特性来获取组件和子物体

先看效果

这里有一个物体，包含a,b,c 三个子物体

c物体上挂有SpriteRenderer组建

想在我们给GameObject添加一个测试脚本Test
正常情况下我们会这么做：

现在我们不这么写了:

下面是运行结果：

可以看到c和SpriteRenderer都拿到了
如果我们想自动为c附加个Button组件
可以直接这样：

运行后我们就可以看到Button了

很简单省事吧。
下面是代码

---

PathAttr.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;

[AttributeUsage(AttributeTargets.Field)]
public class PathAttr : Attribute {

    public string path = "";
    public int type = 1;
    public PathAttr(string path){
        this.path = path;
    }

    public PathAttr(string path, int type){
        this.path = path;
        this.type = type;
    }
}

PathMono.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using UnityEngine;
using UnityEngine.UI;

public class PathMono : MonoBehaviour
{
    private void InitAdd(string path, FieldInfo fi)
    {
        Type type = fi.FieldType;
        string[] pathes = path.Split('/');
        Transform nowPos = transform;

        if (!string.IsNullOrEmpty(path))
        {
            for (int i = 0; i < pathes.Length; i++)
            {
                string nodeName = pathes[i];
                Transform trans = nowPos.FindChild(nodeName);
                if (trans == null)
                {
                    GameObject newGO = new GameObject(nodeName);
                    newGO.transform.SetParent(nowPos);
                    nowPos = newGO.transform;
                    continue;
                }
                else
                {
                    nowPos = trans;
                    continue;
                }
            }
        }
        if (type.IsSubclassOf(typeof(Component)))
        {
            Component c = nowPos.GetComponent(type);
            if (c == null)
                c = nowPos.gameObject.AddComponent(type);
            fi.SetValue(this, c);
        }
        else if (type == typeof(GameObject))
        {
            fi.SetValue(this, nowPos.gameObject);
        }
    }

    public void Init()
    {
        BindingFlags flag = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public;
        FieldInfo[] fi = this.GetType().GetFields(flag);
        for (int i = 0; i < fi.Length; i++)
        {
            FieldInfo f = fi[i];
            PathAttr mn = Attribute.GetCustomAttribute(f, typeof(PathAttr)) as PathAttr;
            if (mn == null) continue;
            if (mn.type == 2)
            {
                InitAdd(mn.path, f);
                continue;
            }
            string path = mn.path;
            Transform trs = null;
            if (string.IsNullOrEmpty(path))
            {
                trs = transform;
            }
            else
            {
                trs = transform.FindChild(path);
            }

            if (trs == null)
            {
                if (mn.type == 1)
                {
                    continue;
                }
                else if (mn.type == 3)
                {
                    InitAdd(path, f);
                }
            }
            else
            {

                if (f.FieldType.IsSubclassOf(typeof(Component)))
                {
                    Component c = trs.GetComponent(f.FieldType);
                    if(c == null && mn.type == 3){
                        c = trs.gameObject.AddComponent(f.FieldType);
                    }
                    f.SetValue(this, c);
                }
                else if (f.FieldType == typeof(GameObject))
                {
                    f.SetValue(this, trs.gameObject);
                }
                else if (f.FieldType == typeof(Transform))
                {
                    f.SetValue(this, trs);
                }
            }
        }
    }
}