Unity中使用UnityWebRequest进行网络和本地图片加载 |
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Unity中使用UnityWebRequest进行网络和本地图片加载
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在实际项目中，往往会有一些需求是要从网络上加载图片展示出来。例如玩家的头像，公告大图和一些需要加载的展示的图片，这时就需要用代码实现从网络上加载必要的图片资源。 更新迭代版本的Unity已经在逐步放弃对WWW的支持，推出UnityWebRequest，详见Unity资源存放与加载-本地资源 更新资源。 UnityWebRequest同时也支持AssetsBundle，xml等文件资源的下载。 本文在基于UnityWebRequest的基础上，实现网络图片和本地磁盘图片的加载，并且实现在屏幕上。 先看看使用WWW是怎么完成图片加载的： using (WWW www = new WWW(url)) { yield return www; if (string.IsNullOrEmpty(www.error)) { //获取到链接中的图片 Texture2D texture = www.texture; } }这段代码比较简单，返回的www.texture就是链接图片，这样就完成了简单的图片加载了。 但是，实际上，通常需要将图片加载内存和缓存到本地，以便在下一次可以很快的加载，而不用再次从网络上拉取。 流程：
关键代码：github地址 ///LoadImageMgr.cs using System.Collections; using System.Collections.Generic; using UnityEngine; using System; using System.IO; using UnityEngine.Networking; public class LoadImageMgr { /// /// download from web or hard disk /// /// /// callback /// public IEnumerator LoadImage(string url, Action loadEnd) { Texture2D texture = null; //先从内存加载 if (imageDic.TryGetValue(url,out texture)) { loadEnd.Invoke(texture); yield break; } string savePath = GetLocalPath(); string filePath = string.Format("file://{0}/{1}.png", savePath, UnityUtil.MD5Encrypt(url)); //from hard disk bool hasLoad = false; if (Directory.Exists(filePath)) yield return DownloadImage(filePath, (state, localTexture) => { hasLoad = state; if (state) { loadEnd.Invoke(localTexture); if (!imageDic.ContainsKey(url)) imageDic.Add(url, localTexture); } }); if (hasLoad) yield break; //loaded //from web yield return DownloadImage(url, (state, downloadTexture) => { hasLoad = state; if (state) { loadEnd.Invoke(downloadTexture); if (!imageDic.ContainsKey(url)) imageDic.Add(url, downloadTexture); Save2LocalPath(url, downloadTexture); } }); } public IEnumerator DownloadImage(string url, Action downloadEnd) { using (UnityWebRequest request = new UnityWebRequest(url)) { DownloadHandlerTexture downloadHandlerTexture = new DownloadHandlerTexture(true); request.downloadHandler = downloadHandlerTexture; yield return request.Send(); if (string.IsNullOrEmpty(request.error)) { Texture2D localTexture = downloadHandlerTexture.texture; downloadEnd.Invoke(true, localTexture); } else { downloadEnd.Invoke(false, null); Debug.Log(request.error); } } } /// /// save the picture /// /// /// private void Save2LocalPath(string url, Texture2D texture) { byte[] bytes = texture.EncodeToPNG(); string savePath = GetLocalPath(); try { File.WriteAllBytes( string.Format("{0}/{1}.png", savePath , UnityUtil.MD5Encrypt(url)), bytes); } catch(Exception ex) { Debug.LogError(ex.ToString()); } } /// /// get which path will save /// /// private string GetLocalPath() { string savePath = Application.persistentDataPath + "/pics"; #if UNITY_EDITOR savePath = Application.dataPath + "/pics"; #endif if (!Directory.Exists(savePath)) { Directory.CreateDirectory(savePath); } return savePath; } private Dictionary imageDic = new Dictionary(); public static LoadImageMgr instance { get; private set; } = new LoadImageMgr(); }///LoadImageHelper.cs using System; using System.Collections; using UnityEngine; using UnityEngine.UI; public class LoadImageHelper : MonoBehaviour { string defaultUrl = "http://avatar.csdnimg.cn/1/E/6/2_u013012420.jpg"; /// /// use this to load image /// /// /// public void LoadImage(RawImage rawImage, string url) { if (string.IsNullOrEmpty(url)) { url = defaultUrl; } StartCoroutine(LoadTeture(url, (tex) => { rawImage.texture = tex; })); } IEnumerator LoadTeture(string url, Action cb) { yield return LoadImageMgr.instance.LoadImage(url, cb); } }
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