Warning: As a former StrongLoop Labs project, the Android SDK may lack usability, completeness, documentation, and robustness, and may be outdated. StrongLoop/IBM is no longer maintaining this project actively, however we do provide support for our paying customers through usual IBM support channels.
See also:
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The LoopBack Android SDK provides classes that enable apps to upload, store and retrieve files from a LoopBack application using the LoopBack Storage service. See Storage component for information on how to create the corresponding LoopBack server application.
The relevant classes are:
ContainerRepository
provides methods for creating and querying containers.FileRepository
provides methods for querying existing files and uploading new files.Container
represents an instance of a server-side container and provides shortcuts for some of the FileRepository methods.File
represents an instance of a server-side file, exposes additional metadata like the public URL and provides methods for downloading the file to the Android device.Note:
All classes are in the package com.strongloop.android.loopback. Since the Java platform provides a File class too,
you may need to use fully qualified names to tell the compiler which class you want to use in your code:
com.strongloop.android.loopback.File from the LoopBack Android SDK
java.io.File from the Java platform
ContainerRepositorycontainerRepo = adapter.createRepository(ContainerRepository.class);
containerRepo.create("container-name", new ObjectCallback<Container>() {
@Override
public void onSuccess(Container container) {
// container was created
}
@Override
public void onError(Throwable error) {
// request failed
}
});
containerRepo.get("container-name", new ObjectCallback<Container>() {
@Override
public void onSuccess(Container container) {
// container was found
}
@Override
public void onError(Throwable error) {
// request failed
}
});
containerRepo.getAll(new ListCallback<Container>() {
@Override
public void onSuccess(List<Container> containers) {
// "containers" hold all items found
}
@Override
public void onError(Throwable error) {
// request failed
}
});
All files live inside a container. The examples below assume you have a container object acquired by one of the methods described in the previous section.
// same as container.getFileRepository().getAll(callback)
container.getAllFiles(new ListCallback<File>() {
@Override
public void onSuccess(List<File> files) {
// process files
}
@Override
public void onError(Throwable error) {
// request failed
}
});
// same as container.getFileRepository.get("file-name", callback)
container.getFile("file-name", new ObjectCallback<File>() {
@Override
public void onSuccess(File file) {
// use the file
}
@Override
public void onError(Throwable error) {
// request failed
}
});
java.io.File localFile = new java.io.File("path/to/file.txt");
// same as container.getFileRepository.upload(localFile, callback)
container.upload(localFile, new ObjectCallback<File>() {
@Override
public void onSuccess(File remoteFile) {
// localFile was uploaded
// call `remoteFile.getUrl()` to get its URL
}
@Override
public void onError(Throwable error) {
// upload failed
}
});
String fileName = "hello.txt";
byte[] content = "Hello world".getBytes("UTF-8");
String contentType = "text/plain";
// same as container.getFileRepository().upload(fileName,...);
container.upload(fileName, content, contentType,
new ObjectCallback<File>() {
@Override
public void onSuccess(File remoteFile) {
// file was uploaded
}
@Override
public void onError(Throwable error) {
// upload failed
}
}
);
File remoteFile; // obtained by one of the methods shown above
java.io.File localFile = new java.io.File("path/to/file.txt");
remoteFile.download(localFile, new VoidCallback() {
@Override
public void onSuccess() {
// localFile contains the content
}
@Override
public void onError(Throwable error) {
// download failed
}
});
File remoteFile;// obtained by one of the methods shown above
remoteFile.download(new File.DownloadCallback() {
@Override
public void onSuccess(byte[] content, String contentType) {
// downloaded
}
@Override
public void onError(Throwable error) {
// download failed
}
});
File remoteFile; // obtained by one of the methods shown above
remoteFile.delete(new Void() {
@Override
public void onSuccess() {
// the file was deleted
}
@Override
public void onError(Throwable error) {
// request failed
}
});
For example, consider an application for submitting insurance claims. To submit a claim, one has to attach documents proving the validity of the claim, such as pictures of the damaged property.
The LoopBack server will track claims using a Claim model. Supporting documents will be stored in a storage service.
There will be one container for every claim record.
The Android application will enable users to view documents attached to a claim and to attach more documents.
See Storage component for information on setting up the server application that uses the LoopBack storage service.
To avoid extra checks further down the line, the app will create the container when the user enters a new claim in the system as shown below:
ContainerRepository containerRepo = adapter.createRepository(ContainerRepository.class);
containerRepo.create(claim.getId().toString(), new ObjectCallback<Container>() {
@Override
public void onSuccess(Container container) {
// container was created, save it
activity.setContainer(container);
// and continue to the next activity
}
@Override
public void onError(Throwable error) {
// request failed, report an error
}
});
To display a list of documents that are already uploaded, we need to fetch all files in the container associated with the current claim as follows:
activity.getContainer().getAllFiles(new ListCallback<File>() {
@Override
public void onSuccess(List<File> remoteFiles) {
// populate the UI with documents
}
@Override
public void onError(Throwable error) {
// request failed, report an error
}
}
To display the document, the app downloads its content and builds a Bitmap object that it can display on the Android device:
void displayDocument(File remoteFile) {
file.download(new File.DownloadCallback() {
@Override
public void onSuccess(byte[] content, String contentType) {
Bitmap image = BitmapFactory.decodeByteArray(content, 0, content.length);
// display the image in the GUI
}
@Override
public void onError(Throwable error) {
// download failed, report an error
}
});
}
To keep this example simple, we will skip details on how to take pictures in Android (for information on this, see the Android Camera docs). Once the picture is taken, the app uploads it to the storage service and updates the list of all documents:
camera.takePicture(
null, /* shutter callback */
null, /* raw callback */
null, /* postview callback */
new Camera.PictureCallback() {
/* jpeg callback */
@Override
void onPictureTaken(byte[] data, Camera camera) {
// A real app would probably ask the user to provide a file name
String fileName = UUID.randomUUID().toString() - ".jpg";
activity.getContainer().upload(fileName, data, "image/jpeg",
new ObjectCallback<File>() {
@Override
public void onSuccess(File remoteFile) {
// Update GUI - add remoteFile to the list of documents
}
@Override
public void onError(Throwable error) {
// upload failed
}
}
);
}
}
);