java - 回调怪异行为(Android、Picasso 库)

Question

我正在使用 Picasso 库来管理我的图像上传和缓存。当我尝试执行此代码时:

    Picasso.with(this)
        .load(AppServer.getImageUrl() + "/" + eventInfo.getImageName())
        .placeholder(R.drawable.calendar)
        .error(R.drawable.calendar)
        .into(new Target()
        {

            @Override
            public void onPrepareLoad(Drawable drawable) 
            {
            }

            @Override
            public void onBitmapLoaded(Bitmap photo, Picasso.LoadedFrom from)
            {
                cropImage(photo); //not getting here
            }

            @Override
            public void onBitmapFailed(Drawable arg0) 
            {
            }
        });  

我没有进入 onBitmapLoaded 回调。只有当我关闭 Activity (返回)并重新打开它时，我才能看到图像(进入 onBitmapLoaded)。

但是，如果我通过将一些 Toast 消息添加到 onPrepareLoad 回调中来更改我的代码，则一切正常。这是完整的代码:

    Picasso.with(this)
        .load(AppServer.getImageUrl() + "/" + eventInfo.getImageName())
        .placeholder(R.drawable.calendar)
        .error(R.drawable.calendar)
        .into(new Target()
        {

            @Override
            public void onPrepareLoad(Drawable drawable) 
            {
                Toast.makeText(thisActivity, "message", Toast.LENGTH_LONG).show();
            }

            @Override
            public void onBitmapLoaded(Bitmap photo, Picasso.LoadedFrom from)
            {
                cropImage(photo);
            }

            @Override
            public void onBitmapFailed(Drawable arg0) 
            {
            }
        });

为什么 Toast 让它起作用？有什么问题吗？

Answer 1

我通过将 Target 实例声明为类成员来解决这个问题。然后初始化它。像这样:

    target = new Target()
    {

        @Override
        public void onPrepareLoad(Drawable drawable) 
        {
        }

        @Override
        public void onBitmapLoaded(Bitmap photo, Picasso.LoadedFrom from)
        {
            cropEventImage(photo);
        }

        @Override
        public void onBitmapFailed(Drawable arg0) 
        {
        }
    };

    Picasso.with(this)
        .load(AppServer.getImageUrl() + "/" + eventInfo.getImageName())
        .placeholder(R.drawable.calendar)
        .error(R.drawable.calendar)
        .into(target);