How to list objects in a bucket by using the Android SDK - Object Storage Service

This topic describes how to list objects in a bucket, such as all objects in the bucket, a specific number of objects, and objects whose names contain a specific prefix.

Usage notes

Before you run the sample code in this topic, you must create an OSSClient instance by using methods such as using a custom domain name or Security Token Service (STS). For more information, see Initialization (Android SDK).

List a specific number of objects

The following sample code provides an example on how to list 20 objects in a bucket named examplebucket:

// Specify the bucket name. For example, examplebucket.
ListObjectsRequest request = new ListObjectsRequest("examplebucket");
// Specify the maximum number of objects to return. If this parameter is not set, the default value is 100. The value of maxKeys cannot be greater than 1,000.
request.setMaxKeys(20);

oss.asyncListObjects(request, new OSSCompletedCallback<ListObjectsRequest, ListObjectsResult>() {
    @Override
    public void onSuccess(ListObjectsRequest request, ListObjectsResult result) {
        for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
            Log.i("ListObjects", objectSummary.getKey());
        }
    }

    @Override
    public void onFailure(ListObjectsRequest request, ClientException clientException, ServiceException serviceException) {
        // Handle request exceptions.
        if (clientException != null) {
            // Handle client-side exceptions, such as network errors.
            clientException.printStackTrace();
        }
        if (serviceException != null) {
            // Handle server-side exceptions.
            Log.e("ErrorCode", serviceException.getErrorCode());
            Log.e("RequestId", serviceException.getRequestId());
            Log.e("HostId", serviceException.getHostId());
            Log.e("RawMessage", serviceException.getRawMessage());
        }
    }
});

List objects whose names contain a specific prefix

The following sample code provides an example on how to list the objects whose names contain the file prefix in a bucket named examplebucket:

// Specify the bucket name. For example, examplebucket.
ListObjectsRequest request = new ListObjectsRequest("examplebucket");
// Specify the prefix.
// Returns all objects whose names start with the specified prefix. For example, a prefix of 'a' returns objects such as abc.txt and abcd.jpg.
request.setPrefix("file");

oss.asyncListObjects(request, new OSSCompletedCallback<ListObjectsRequest, ListObjectsResult>() {
    @Override
    public void onSuccess(ListObjectsRequest request, ListObjectsResult result) {
        for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
            Log.i("ListObjects", objectSummary.getKey());
        }
    }

    @Override
    public void onFailure(ListObjectsRequest request, ClientException clientException, ServiceException serviceException) {
        // Handle request exceptions.
        if (clientException != null) {
            // Handle client-side exceptions, such as network errors.
            clientException.printStackTrace();
        }
        if (serviceException != null) {
            // Handle server-side exceptions.
            Log.e("ErrorCode", serviceException.getErrorCode());
            Log.e("RequestId", serviceException.getRequestId());
            Log.e("HostId", serviceException.getHostId());
            Log.e("RawMessage", serviceException.getRawMessage());
        }
    }
});

List objects whose names are alphabetically after the value of marker

The following sample code provides an example on how to list the objects whose names are alphabetically after the object named exampleobject.txt in a bucket named examplebucket:

// Specify the bucket name. For example, examplebucket.
ListObjectsRequest request = new ListObjectsRequest("examplebucket");
// Lists objects that alphabetically follow the marker.
// If the marker does not correspond to an existing object, the list starts from the alphabetical position of the marker's value.
request.setMarker("exampleobject.txt");

oss.asyncListObjects(request, new OSSCompletedCallback<ListObjectsRequest, ListObjectsResult>() {
    @Override
    public void onSuccess(ListObjectsRequest request, ListObjectsResult result) {
        for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
            Log.i("ListObjects", objectSummary.getKey());
        }
    }

    @Override
    public void onFailure(ListObjectsRequest request, ClientException clientException, ServiceException serviceException) {
        // Handle request exceptions.
        if (clientException != null) {
            // Handle client-side exceptions, such as network errors.
            clientException.printStackTrace();
        }
        if (serviceException != null) {
            // Handle server-side exceptions.
            Log.e("ErrorCode", serviceException.getErrorCode());
            Log.e("RequestId", serviceException.getRequestId());
            Log.e("HostId", serviceException.getHostId());
            Log.e("RawMessage", serviceException.getRawMessage());
        }
    }
});

List all objects in a bucket by page

The following sample code provides an example on how to list all objects in a bucket named examplebucket by page. Up to 20 objects can be listed on each page.

private String marker = null;
private boolean isCompleted = false;

// List all objects by page.
public void getAllObject() {
    do {
        OSSAsyncTask task = getObjectList();
        // Block the thread to get the NextMarker. To fetch the next page, set the marker to the NextMarker value from the previous response. No marker is needed for the first page.
        // This example blocks the thread in a loop to get the NextMarker for pagination. In a production environment, decide whether to block the thread based on your application's requirements.
        task.waitUntilFinished();
    } while (!isCompleted);
}

// List one page of objects.
public OSSAsyncTask getObjectList() {
    // Specify the bucket name.
    ListObjectsRequest request = new ListObjectsRequest("examplebucket");
    // Specify the maximum number of objects to return per page. If this parameter is not set, the default value is 100. The value of maxKeys cannot be greater than 1,000.
    request.setMaxKeys(20);
    request.setMarker(marker);

    OSSAsyncTask task = oss.asyncListObjects(request, new OSSCompletedCallback<ListObjectsRequest, ListObjectsResult>() {
        @Override
        public void onSuccess(ListObjectsRequest request, ListObjectsResult result) {
            for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
                Log.i("ListObjects", objectSummary.getKey());
            }
            // Last page of results.
            if (!result.isTruncated()) {
                isCompleted = true;
                return;
            }
            // The marker for the next page of results.
            marker = result.getNextMarker();
        }

        @Override
        public void onFailure(ListObjectsRequest request, ClientException clientException, ServiceException serviceException) {
            isCompleted = true;
            // Handle request exceptions.
            if (clientException != null) {
                // Handle client-side exceptions, such as network errors.
                clientException.printStackTrace();
            }
            if (serviceException != null) {
                // Handle server-side exceptions.
                Log.e("ErrorCode", serviceException.getErrorCode());
                Log.e("RequestId", serviceException.getRequestId());
                Log.e("HostId", serviceException.getHostId());
                Log.e("RawMessage", serviceException.getRawMessage());
            }
        }
    });
    return task;
}

List objects whose names contain a specific prefix by page

The following sample code provides an example on how to list the objects whose names contain the file prefix in a bucket named examplebucket by page. Up to 20 objects can be listed on each page.

private String marker = null;
private boolean isCompleted = false;

// List all objects with the specified prefix by page.
public void getAllObject() {
    do {
        OSSAsyncTask task = getObjectList();
        // Block the thread to get the NextMarker. To fetch the next page, set the marker to the NextMarker value from the previous response. No marker is needed for the first page.
        // This example blocks the thread in a loop to get the NextMarker for pagination. In a production environment, decide whether to block the thread based on your application's requirements.
        task.waitUntilFinished();
    } while (!isCompleted);
}

// List one page of objects.
public OSSAsyncTask getObjectList() {
    // Specify the bucket name.
    ListObjectsRequest request = new ListObjectsRequest("examplebucket");
    // Specify the maximum number of objects to return per page. If this parameter is not set, the default value is 100. The value of maxKeys cannot be greater than 1,000.
    request.setMaxKeys(20);
    // Specify the prefix.
    // Returns all objects whose names start with the specified prefix. For example, a prefix of 'a' returns objects such as abc.txt and abcd.jpg.
    request.setPrefix("file");
    request.setMarker(marker);

    OSSAsyncTask task = oss.asyncListObjects(request, new OSSCompletedCallback<ListObjectsRequest, ListObjectsResult>() {
        @Override
        public void onSuccess(ListObjectsRequest request, ListObjectsResult result) {
            for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
                Log.i("ListObjects", objectSummary.getKey());
            }
            // Last page of results.
            if (!result.isTruncated()) {
                isCompleted = true;
                return;
            }
            // The marker for the next page of results.
            marker = result.getNextMarker();
        }

        @Override
        public void onFailure(ListObjectsRequest request, ClientException clientException, ServiceException serviceException) {
            isCompleted = true;
            // Handle request exceptions.
            if (clientException != null) {
                // Handle client-side exceptions, such as network errors.
                clientException.printStackTrace();
            }
            if (serviceException != null) {
                // Handle server-side exceptions.
                Log.e("ErrorCode", serviceException.getErrorCode());
                Log.e("RequestId", serviceException.getRequestId());
                Log.e("HostId", serviceException.getHostId());
                Log.e("RawMessage", serviceException.getRawMessage());
            }
        }
    });
    return task;
}

List the objects whose names contain special characters

If the name of an object contains one of the following special characters, you must encode the object name before you transmit the object. Only URL encoding is supported in OSS.

Single quotation marks (')
Double quotations marks (")
Ampersands (&)
Angle brackets (<>)
Chinese characters

The following sample code provides an example on how to list the objects whose names contain special characters in a bucket named examplebucket:

// Specify the bucket name. For example, examplebucket.
ListObjectsRequest request = new ListObjectsRequest("examplebucket");
// Specify the encoding type for object names.
request.setEncodingType("url");

oss.asyncListObjects(request, new OSSCompletedCallback<ListObjectsRequest, ListObjectsResult>() {
    @Override
    public void onSuccess(ListObjectsRequest request, ListObjectsResult result) {
        for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
            Log.i("ListObjects", URLDecoder.decode(objectSummary.getKey(), "UTF-8"));
        }
    }

    @Override
    public void onFailure(ListObjectsRequest request, ClientException clientException, ServiceException serviceException) {
        // Handle request exceptions.
        if (clientException != null) {
            // Handle client-side exceptions, such as network errors.
            clientException.printStackTrace();
        }
        if (serviceException != null) {
            // Handle server-side exceptions.
            Log.e("ErrorCode", serviceException.getErrorCode());
            Log.e("RequestId", serviceException.getRequestId());
            Log.e("HostId", serviceException.getHostId());
            Log.e("RawMessage", serviceException.getRawMessage());
        }
    }
});

References

For more information about the API operations that you can call to list objects, see GetBucket (ListObjects) and ListObjectsV2(GetBucketV2).
For more information about how to initialize an OSSClient instance, see Initialization.