下载文件

    private string url = "http://....";
    WWW www;
    public Image progressImg;

    private void Update()
    {
        if (www != null)
        {
            if (!www.isDone)
            {
                progressImg.fillAmount = www.progress;//www.progress下载进度
            }
            else
            {
                progressImg.fillAmount = 1;
            }
        }
    }

    /// <summary>
    /// 下载文件
    /// </summary>
    /// <param name="url">下载地址</param>
    /// <param name="file">保存路径</param>
    /// <returns></returns>
    IEnumerator DownLoadTexture(string url, string file)
    {
        
        www = new WWW(url);
        Texture2D tempImage;
        
        yield return www;
        
        if (www.isDone && www.error == null)
        {
            tempImage = www.texture;
            if (tempImage != null)
            {
                byte[] data = tempImage.EncodeToJPG();
                File.WriteAllBytes(file, data);
                isChange = true;
            }
        }
    }