Unity资源管理——使用UnityWebRequest从云端下载Assetbundle包

1.环境

        基于Unity2018.2

2.思路

        1.使用UnityWebRequest.Get方法去获取AB包

        2.在协程中返回UnityWebRequest实例对象的SendWebRequest方法返回值

        3.当UnityWebRequest实例对象IsDone的时候取得数据流，进行文件写入

3.核心代码

       /// <summary>
        /// 保存AssetBundle文件到本地
        /// </summary>
        IEnumerator SaveAssetBundle(string path)
        {
            while (!Caching.ready)
                yield return null;

            using (UnityWebRequest uwr = UnityWebRequest.Get(path))//路径名（例如"file://worksapce/cube.assetbundle"）
            {

                yield return uwr.SendWebRequest();
                if (uwr.error != null)
                    throw new Exception("www download had an error" + uwr.error);
                LoadProgress = uwr.downloadProgress;
                if (uwr.isDone)
                {
                    byte[] results = uwr.downloadHandler.data;
                    Bundle = AssetBundle.LoadFromMemory(uwr.downloadHandler.data);
                    Bytes = uwr.downloadHandler.data;

                    FileInfo fileInfo = new FileInfo(Application.streamingAssetsPath + "/" + Bundle.name);
                    FileStream fs = fileInfo.Create();

                    //fs.Write(字节数组, 开始位置, 数据长度);
                    fs.Write(uwr.downloadHandler.data, 0, uwr.downloadHandler.data.Length);

                    fs.Flush();     //文件写入存储到硬盘
                    fs.Close();     //关闭文件流对象
                    fs.Dispose();   //销毁文件对象
                }
            }
        }