如何使Glide使用以前下载的图像作为占位符

Question

下载新图像时，是否可以在Glide中将以前下载的图像显示为占位符。

就像我使用滑动在imageview中加载了一个图像。现在图像被更改，因此在加载这个新图像时，可以继续显示旧图像（可能来自缓存）。

我想要的是从URL加载新图像时，是否可以将当前图像保留为占位符。

Answer 1

Glide有能力从该URL获取图像的位图，所以只需获取它，然后将其保存到手机中的所需存储中，然后在.placeholder（）中，只需在尝试获取时使用该位图另一张图片，看看这个片段

/** Download the image using Glide **/

Bitmap theBitmap = null;
theBitmap = Glide.
    with(YourActivity.this).
    asBitmap().
    load("Url of your image").
    into(-1, -1).
    get(); //with this we get the bitmap of that url

   saveToInternalStorage(theBitmap, getApplicationContext(), "your preferred image name");

/** Save it on your device **/

public String saveToInternalStorage(Bitmap bitmapImage, Context context, String name){


        ContextWrapper cw = new ContextWrapper(context);
        // path to /data/data/yourapp/app_data/imageDir

        String name_="foldername"; //Folder name in device android/data/
        File directory = cw.getDir(name, Context.MODE_PRIVATE);

        // Create imageDir
        File mypath=new File(directory,name_);

        FileOutputStream fos = null;
        try {

            fos = new FileOutputStream(mypath);

            // Use the compress method on the BitMap object to write image to the OutputStream
            bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, fos);
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        Log.e("absolutepath ", directory.getAbsolutePath());
        return directory.getAbsolutePath();
    }

/** Method to retrieve image from your device **/

public Bitmap loadImageFromStorage(String path, String name)
    {
        Bitmap b;
        String name_= name; //your folderName
        try {
            File f=new File(path, name_);
            b = BitmapFactory.decodeStream(new FileInputStream(f));
            return b;
        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        }
        return null;
    }




/** Retrieve your image from device and set to imageview **/
//Provide your image path and name of the image your previously used.

Bitmap b= loadImageFromStorage(String path, String name)
ImageView img=(ImageView)findViewById(R.id.your_image_id);
img.setImageBitmap(b);