Android Picasso 请求图片时添加referer的问题

服务器端要做图片防盗链，app端请求图片时需要带上特定的referer，通过以下代码，时不时可以成功，但是服务器端回复说有时候收不到referer。

Interceptor代码：

public class PicassoHeaderInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
    Request.Builder request = chain.request().newBuilder();
    request.addHeader("referer", ConstantsValues.IMAGE_REFER);
    return chain.proceed(request.build());
}

}

getPicasso方法:

public static Picasso getPicasso(){
    if(mPicasso==null){
        synchronized (UI.class){
            if(mPicasso==null){
                OkHttpClient okHttpClient = new OkHttpClient();
                okHttpClient.interceptors().add(new PicassoHeaderInterceptor());
                OkHttpDownloader okHttpDownloader = new OkHttpDownloader(okHttpClient);
                mPicasso = new Picasso.Builder(getContext()).downloader(okHttpDownloader).build();
            }
        }
    }
    return mPicasso;
}

加载图片的方法:

public static void displayCircleImage(ImageView iv,String url){
    getPicasso().with(getContext()).load(url)
            .placeholder(R.drawable.ic_image_loading)
            .error(R.drawable.ic_launcher)
            .transform(new CircleTransform())
            .into(iv);
}

public static void displayImage(ImageView iv,String url){
    getPicasso().with( iv.getContext() )
            .load(url)
            .placeholder(R.drawable.ic_image_loading)
            .error(R.drawable.ic_launcher)
            .config(Bitmap.Config.RGB_565)
            .transform(new ZoomTransformation(UI.dip2px(200)))
            .into(iv);
}

本来前段时间刚完成referer的时候是都可以的，但是这2天只有偶尔几张图片能够获取到，百思不得其解，希望各位能够帮帮忙

https://www.zhihu.com/question/38287658