Unity从网络/本地异步获取图片（微信头像）

系统管理员 2022-09-30 11:46 149阅读 0赞

最近在写获取微信头像的代码, 通过微信开放平台SDK授权登录后, 个人信息请求中会返回一个微信头像的url, 类似于这种形式：

"headimgurl": "http://wx.qlogo.cn/mmopen/g3MonUZtNHkdmzicIlibx6iaFqAc56vxLSUfpb6n5WKSYVY0ChQKkiaJSgQ1dZuTOgvLLrhJbERQQ4eMsv84eavHiaiceqxibJxCfHe/0",

注意,最后的/0代表大头像 /46代表小头像

如何读取这个头像, 首先想到的是协程, 然后通过WWW类,用Http请求来获取它;

当然之后还会考虑去获取所有好友的微信头像, 这就需要将很多图片的URL下载下来保存在本地, 所以百度学习了一下unity本地存取图片的方法.

主要用到了c\#的gethashcode()来区分图片, 下载图片后将Texture压缩成bytes存在本地, www类加协程异步读取本地图片。

using UnityEngine;
    using UnityEngine.UI;
    using System.Collections;
    using System.IO;
    
    public class AsyncImageDownload : MonoBehaviour
    {
        public Sprite myWXPic;
    
        private static AsyncImageDownload _instance = null;
        public static AsyncImageDownload GetInstance() { return Instance; }
        public static AsyncImageDownload Instance
        {
            get
            {
                if (_instance == null)
                {
                    GameObject obj = new GameObject("AsyncImageDownload");
                    _instance = obj.AddComponent<AsyncImageDownload>();
                    DontDestroyOnLoad(obj);
                    _instance.Init();
                }
                return _instance;
            }
        }
    
        public bool Init()
        {
            if (!Directory.Exists(Application.persistentDataPath + "/ImageCache/"))
            {
                Directory.CreateDirectory(Application.persistentDataPath + "/ImageCache/");
            }
            myWXPic = null;
            return true;
    
        }
    
        public void SetAsyncImage(string url, Image image)
        {
            //开始下载图片前，将UITexture的主图片设置为占位图
            if (myWXPic != null)
            {
                image.sprite = myWXPic;
                return;
            }
    
            //判断是否是第一次加载这张图片
            if (!File.Exists(path + url.GetHashCode()))
            {
                //如果之前不存在缓存文件
                StartCoroutine(DownloadImage(url, image));
            }
            else
            {
                StartCoroutine(LoadLocalImage(url, image));
            }
        }
    
        IEnumerator DownloadImage(string url, Image image)
        {
            Debug.Log("downloading new image:" + path + url.GetHashCode());//url转换HD5作为名字
            WWW www = new WWW(url);
            yield return www;
    
            Texture2D tex2d = www.texture;
            //将图片保存至缓存路径
            byte[] pngData = tex2d.EncodeToPNG();                         //将材质压缩成byte流
            File.WriteAllBytes(path + url.GetHashCode(), pngData);        //然后保存到本地
    
            Sprite m_sprite = Sprite.Create(tex2d, new Rect(0, 0, tex2d.width, tex2d.height), new Vector2(0, 0));
            image.sprite = m_sprite;
            myWXPic = m_sprite;
        }
    
        IEnumerator LoadLocalImage(string url, Image image)
        {
            string filePath = "file:///" + path + url.GetHashCode();
    
            Debug.Log("getting local image:" + filePath);
            WWW www = new WWW(filePath);
            yield return www;
    
            Texture2D texture = www.texture;
            Sprite m_sprite = Sprite.Create(texture, new Rect(0, 0, texture.width, texture.height), new Vector2(0, 0));
            image.sprite = m_sprite;
            myWXPic = m_sprite;
        }
    
        public string path
        {
            get
            {
                //pc,ios //android :jar:file//
                return Application.persistentDataPath + "/ImageCache/";
    
            }
        }
    }

本地保存多张微信头像：

using UnityEngine;
    using UnityEngine.UI;
    using System.Collections;
    using System.IO;
    using System.Collections.Generic;
    
    public class AsyncImageDownload : MonoBehaviour
    {
        private Sprite[] wxPic;                              //存在内存中的头像数组
        Dictionary<int, int> code2PicID;                     //url的hashcode -> spriteID
        private static int spriteCnt;
    
        private static AsyncImageDownload _instance = null;
        public static AsyncImageDownload GetInstance() { return Instance; }
        public static AsyncImageDownload Instance
        {
            get
            {
                if (_instance == null)
                {
                    GameObject obj = new GameObject("AsyncImageDownload");
                    _instance = obj.AddComponent<AsyncImageDownload>();
                    DontDestroyOnLoad(obj);
                    _instance.Init();
                }
                return _instance;
            }
        }
    
        public bool Init()
        {
            if (!Directory.Exists(Application.persistentDataPath + "/ImageCache/"))
            {
                Directory.CreateDirectory(Application.persistentDataPath + "/ImageCache/");
            }
            wxPic = new Sprite[55];                  //默认不超过55个url
            spriteCnt = 0;
            code2PicID = new Dictionary<int, int>();
            return true;
        }
    
        public void SetAsyncImage(string url, Image image)
        {
            //开始下载图片前，将UITexture的主图片设置为占位图
            int code = url.GetHashCode();
            if(code2PicID.ContainsKey(code))
            {
                image.sprite = wxPic[ code2PicID[code] ];
            }
            else       //如果之前不存在缓存中  就用WWW类下载
            {
                
                if (spriteCnt >= 54)
                    return;
                StartCoroutine(DownloadImage(url, image, code));
            }    
        }
    
        IEnumerator DownloadImage(string url, Image image, int code)
        {
            WWW www = new WWW(url);
            yield return www;
    
            Texture2D tex2d = www.texture;
            //将图片保存至缓存路径
    //        byte[] pngData = tex2d.EncodeToPNG();                                 不存图片了..
      //      File.WriteAllBytes(path + url.GetHashCode(), pngData);
    
            Sprite m_sprite = Sprite.Create(tex2d, new Rect(0, 0, tex2d.width, tex2d.height), new Vector2(0, 0));
            image.sprite = m_sprite;
            code2PicID[code] = spriteCnt;  
            wxPic[spriteCnt] = m_sprite;
            ++spriteCnt;
    
    
        }
    
        IEnumerator LoadLocalImage(string url, Image image)
        {
            string filePath = "file:///" + path + url.GetHashCode();
       //     Debug.Log("getting local image:" + filePath);
            WWW www = new WWW(filePath);
            yield return www;
    
            Texture2D texture = www.texture;
            Sprite m_sprite = Sprite.Create(texture, new Rect(0, 0, texture.width, texture.height), new Vector2(0, 0));
            image.sprite = m_sprite;
        }
    
        public string path
        {
            get
            {
                //pc,ios //android :jar:file//
                return Application.persistentDataPath + "/ImageCache/";
    
            }
        }
    }