com.exasol.bucketfs.list.ListingRetriever Maven / Gradle / Ivy

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Java library for automating tasks on Exasol's BucketFS.
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package com.exasol.bucketfs.list;

import static com.exasol.bucketfs.BucketConstants.PATH_SEPARATOR;
import static com.exasol.bucketfs.BucketOperation.LIST;

import java.io.IOException;
import java.net.URI;
import java.net.http.*;
import java.net.http.HttpResponse.BodyHandlers;
import java.util.Arrays;
import java.util.Base64;
import java.util.logging.Logger;
import java.util.stream.Stream;

import com.exasol.bucketfs.*;

/**
 * This class retrieves the list of buckets or of objects inside a bucket.
 */
public class ListingRetriever {
    /**
     * @param protocol protocol
     * @param host     host name or IP address for the URI
     * @param port     port
     * @param suffix   e.g. name of the bucket
     * @return {@link URI} made up from the specified elements
     */
    public static URI publicReadUri(final String protocol, final String host, final int port, final String suffix) {
        return URI.create(protocol + "://" + host + ":" + port + "/" + suffix);
    }

    /**
     * @param path remove leading {@link BucketConstants#PATH_SEPARATOR} from this path
     * @return path with potential leading {@link BucketConstants#PATH_SEPARATOR} removed
     */
    public static String removeLeadingSeparator(final String path) {
        return path.startsWith(PATH_SEPARATOR) ? path.substring(1) : path;
    }

    private static final Logger LOGGER = Logger.getLogger(ListingRetriever.class.getName());
    private final HttpClient httpClient;

    /**
     * Create a new instance of {@link ListingRetriever}.
     *
     * @param httpClient HTTP client to access the BucketFS service
     */
    public ListingRetriever(final HttpClient httpClient) {
        this.httpClient = httpClient;
    }

    /**
     * Retrieve the content for the given URI as stream.
     *
     * @param uri          URI to retrieve listing for
     * @param readPassword read password, only relevant for non-public buckets
     * @return stream of strings
     * @throws BucketAccessException in case of failure
     */
    public Stream retrieve(final URI uri, final String readPassword) throws BucketAccessException {
        return Arrays.stream(requestListing(uri, readPassword).split("\\s+")).sorted();
    }

    private String requestListing(final URI uri, final String readPassword) throws BucketAccessException {
        LOGGER.finest(() -> "Listing contents of URI '" + uri + "'");
        try {
            final HttpRequest request = HttpRequest.newBuilder(uri) //
                    .header("Authorization", encodeBasicAuth(readPassword)) //
                    .build();
            final HttpResponse response = this.httpClient.send(request, BodyHandlers.ofString());
            HttpResponseEvaluator.evaluate(uri, LIST, response.statusCode());
            return response.body();
        } catch (final IOException exception) {
            throw BucketAccessException.downloadIoException(uri, LIST, exception);
        } catch (final InterruptedException exception) {
            Thread.currentThread().interrupt();
            throw BucketAccessException.downloadInterruptedException(uri, LIST);
        }
    }

    private String encodeBasicAuth(final String readPassword) {
        return "Basic " + Base64.getEncoder().encodeToString(("r:" + readPassword).getBytes());
    }
}