Android-从URL获取，保存和检索图像

Question

I have a database of recipes, each of which has an image.

The database can be updated from a JSON feed. I then need to retrieve any new images for a newly added recipe. I'm having issues getting an image from a URL, saving it and then updating a recipe with that image.

There are a lot of different answers on Stack Overflow and other sites. Often I can get to what I would expect to be a working point. Where images appear to be getting saved, and any debug print outs I add in show what I expect, but I cannot update my ImageView. By that I mean it remains blank.

I'm not sure if my issue is simply a poor attempt to update the ImageView, or a problem when saving the images. This code is a bit sloppy and inefficient at the moment. I've tried 10-15 variations on this from suggested other posts and have had no luck. Any help would be greatly appreciated.

Manifest

/* I have these two set (Not sure both are necessary) */
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Main frontend class

/* Create databaseHelper */
DatabaseHelper db = new DatabaseHelper(getApplicationContext());

/* ImageView to update image of */
ImageView foodpic = (ImageView)findViewById(R.id.foodpic);

/* Check if image is already available in drawable folder */
int resID = this.getResources().getIdentifier(filename, "drawable", "mypackage.name");
if (resID == 0) {
    /* If not, call function to retrieve from external storage */
    newPic = db.getOutputMediaFile(origFilename);

    if(newPic.exists()) {
        myBitmap = BitmapFactory.decodeFile(newPic.getAbsolutePath());
        foodpic.setImageBitmap(myBitmap);
        foodpic.invalidate(); /* Tried with and without this */
    }
}

DatabaseHelper function to retrieve image saved from URL

public File getOutputMediaFile(String filename){
    /* Dir I'm (attempting) to save and retrieve images from */
    File mediaStorageDir = new File(Environment.getExternalStorageDirectory() + "/Android/data/mypackage.name/Files"); 

    /* Create the storage directory if it does not exist */
if (! mediaStorageDir.exists()){
    if (! mediaStorageDir.mkdirs()){
        return null;
    }
}

    /* Get file extension */
    String[] fileNameSplit = filename.split("\\.");
String extension = fileNameSplit[(fileNameSplit.length-1)];

    /* Get filename, remove special chars & make lowercase */
int extensionIndex = filename.lastIndexOf(".");
filename = filename.substring(0, extensionIndex);
filename = filename.toLowerCase(Locale.getDefault());
filename = filename.replaceAll("[^a-z0-9]", "");

    /* Re-make filename to save image as */
    String mImageName="r"+filename+"."+extension;

    /* Get file 
    mediaFile = new File(mediaStorageDir.getPath() + File.separator + mImageName);
    return mediaFile;
}

DatabaseHelper function to save image from URL - Called per recipe/image added to the database, if image not found in drawable folder.

public static void saveImage(String imageUrl, String destinationFile, String extension) throws IOException {

URL url = new URL (imageUrl);
InputStream input = url.openStream();
try {
    File storagePath = Environment.getExternalStorageDirectory();
    OutputStream output = new FileOutputStream (new File(storagePath,destinationFile));
    try {
        byte[] buffer = new byte[2048];
        int bytesRead = 0;
    while ((bytesRead = input.read(buffer, 0, buffer.length)) >= 0) {
        output.write(buffer, 0, bytesRead);
            }
    } finally {
    output.close();
}
} finally {
    input.close();
}

*Formatting.

Answer 1

Store URL as string in DB and display it with Image Loader is more easy, but doesn't work off line ,if ur apps need internet to work, the image loader could be better. android-loading-image-from-url-http

Answer 2

I ended up using this library.

It's not an ideal solution as I'd have preferred to look through this library, understand it fully and explain it for others who may need a similar answer. But for now, people attempting to do something similar should be able to use this too.

https://code.google.com/p/imagemanager/