WWW和IO方式加载图片到UGUI的Image上显示出来对比

WWW和IO方式加载图片到UGUI的Image上显示出来对比，后者所用时间较短，速度快，代码如下：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using System.IO;
public class wwwLoadImage : MonoBehaviour {
    public Image image;
    public Image image2;
    // Use this for initialization
    void Start () {
        Debug.Log(Application.dataPath);
        StartCoroutine(GetImage());

        GetImageByIO();

    }
    
    // Update is called once per frame
    void Update () {
        
    }


    IEnumerator GetImage() {

        double startTime = (double)Time.time;
        WWW www = new WWW(@"file://"+ Application.dataPath+"/logo.png");
        yield return www;
        if (www.error!=null)
        {
            yield return null;
        }
        Texture2D texture = www.texture;
        GetImage(texture, image);
        startTime = (double)Time.time - startTime;
        Debug.Log("WWW加载用时:" + startTime);
    }
    /// <summary>
    /// 以IO方式进行加载
    /// </summary>
    void GetImageByIO() {
        double startTime=(double)Time.time;

        //创建文件读取流   路径  创建模式  读取权限
        FileStream fileSteam = new FileStream(Application.dataPath + "/logo.png", FileMode.Open, FileAccess.Read);
      
        fileSteam.Seek(0, SeekOrigin.Begin);

        //创建文件长度缓冲区
        byte[] bytes = new byte[fileSteam.Length];
        //读取文件
        fileSteam.Read(bytes, 0, (int)fileSteam.Length);
        //释放文件读取流
        fileSteam.Close();
        fileSteam.Dispose();
        fileSteam = null;
        Texture2D tex = new Texture2D(200, 100);
        tex.LoadImage(bytes);

        GetImage(tex, image2);
        startTime = (double)Time.time - startTime;
        Debug.Log("IO加载用时:" + startTime);

    }


    private void GetImage(Texture2D tex, Image image) {
        //创建Sprite
        Sprite sprite = Sprite.Create(tex, new Rect(0, 0, tex.width, tex.height), new Vector2(0.5f, 0.5f));
   
        image.sprite = sprite;
        image.SetNativeSize();
    }

}