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(); 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(); 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/"; } } }