2020-08-17 Unity使用旧版WWW下载图片，音频等

简单封装了一个下载类，记录一下

 /// <summary>
    /// 异步设置图片
    /// </summary>
    private void SetAsyncImage(string url, Image image)
    {
        ////是否第一次加载
        if (!File.Exists(Path + ImagePath + url.GetHashCode()))
        {
            StartCoroutine(LoadWebImage(url, image));
        }
        else
        {
            StartCoroutine(LoadLocalImage(url, image));
        }
    }

 /// <summary>
    /// 加载网图
    /// </summary>
    IEnumerator LoadWebImage(string url, Image image)
    {
        if (url != "" || image != null)
        {
//             UnityEngine.Debug.Log(url);
            WWW www = new WWW(url);
            yield return www;

            if (string.IsNullOrEmpty( www.error))
            {
                try
                {
                    Texture2D tex2d = www.texture;
                    if (tex2d != null)
                    {
                        //保存图片
                        byte[] pngData = tex2d.EncodeToPNG();
                        File.WriteAllBytes(Path + ImagePath + url.GetHashCode(), pngData);
                        Sprite m_sprite = Sprite.Create(tex2d, new Rect(0, 0, tex2d.width, tex2d.height), Vector2.zero);
                        image.sprite = m_sprite;
                    }
                    else
                    {
                         UnityEngine.Debug.LogError("LoadWebImage Texture2D null" + " url=" + url);
                    }
                }
                catch (System.Exception error)
                {
                      UnityEngine.Debug.LogError("LoadWebImage exception:"+error + " url=" + url);
                }
            }
            else
            {
                UnityEngine.Debug.LogError("LoadWebImage error:"+www.error + " url="+ url);
            }
        }
    }

/// <summary>
    /// 从本地加载图片
    /// </summary>
    IEnumerator LoadLocalImage(string url, Image image)
    {
        string filePath = "file:///" + Path + ImagePath + url.GetHashCode();
        if (url != "" || image != null)
        {
            WWW www = new WWW(filePath);
            yield return www;

            if (string .IsNullOrEmpty( www.error) )
            {
                Texture2D texture = www.texture;
                if (texture != null)
                {
                    Sprite m_sprite = Sprite.Create(texture, new Rect(0, 0, texture.width, texture.height), new Vector2(0, 0));
                    image.sprite = m_sprite;
                }
                else
                {
                    UnityEngine.Debug.LogError("LoadLocalImage Texture2D null" + " url=" + url);
                }
            }
            else
            {
                UnityEngine.Debug.LogError("LoadLocalImage error:"+www.error + " url=" + url);
            }
        }
    }

 /// <summary>
    //  音效
    /// </summary>
    IEnumerator LoadLocalMusic(string url, AudioSource source)
    {
        string filePath = "file:///" + Path + AudioPath + url.GetHashCode() + suffix;
        if (url != "" || source != null)
        {
            WWW www = new WWW(filePath);
            yield return www;

            if (www.error == null)
            {
                AudioClip clip = www.GetAudioClip();
                if (clip != null)
                {
                    source.clip = clip;
                    source.Play();
                }
                else
                {
                     UnityEngine.Debug.LogError("LoadLocalMusic:" + "clip null " + " url=" + url);
                }
            }
            else
            {
                 UnityEngine.Debug.LogError("LoadLocalMusic:" + www.error + " url=" + url);
            }
        }
    }

    IEnumerator LoadWebMusic(string url, AudioSource source)
    {
        if (url != "")
        {
            WWW www = new WWW(url);
            yield return www;
    
            if (www.error == null)
            {
                try
                {
                    AudioClip clip = www.GetAudioClip();
                    if (clip != null)
                    {
                        File.WriteAllBytes(Path + AudioPath + url.GetHashCode() + suffix, www.bytes);
                        source.clip = clip;
                        source.Play();
                    }
                    else
                    {
                        UnityEngine.Debug.LogError("LoadWebMusic:clip null");
                    }
                }
                catch (System.Exception error)
                {
                     UnityEngine.Debug.LogError("LoadWebMusic:" + error + " url=" + url);
                    throw error;
                }
            }
            else
            {
                 UnityEngine.Debug.LogError("LoadWebMusic:" + www.error + " url=" + url);
            }
        }
    }