S3Location.java

import com.google.common.base.Strings;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * S3Location represents an S3 bucket and a key.
 */
public class S3Location {
    /**
     * Pattern for an S3 URL that captures the bucket and optionally a key
     */
    private static final Pattern S3_URL =
        Pattern.compile("^s3://([^/]+)(?:/(.+))?$");

    private final String bucket;
    private final String key;

    public S3Location(String bucket, String key) {
        if (bucket == null) {
            throw new IllegalArgumentException("bucket cannot be null");
        }
        if (key == null) {
            throw new IllegalArgumentException("key cannot be null");
        }

        this.bucket = bucket;
        this.key = key;
    }

    /**
     * @return the s3 bucket
     */
    public String getBucket() {
        return bucket;
    }

    /**
     * @return the key
     */
    public String getKey() {
        return key;
    }

    /**
     * Parses an S3Location from an s3 style URL
     */
    public static S3Location fromURL(final String s3url) {
        if (s3url == null) {
            throw new IllegalArgumentException("s3url cannot be null");
        }
        Matcher m = S3_URL.matcher(s3url);
        if (!m.matches()) {
            throw  new IllegalArgumentException("s3url is not formatted as an S3 URL");
        }
        return new S3Location(m.group(1), Strings.nullToEmpty(m.group(2)));
    }

    /**
     * @return this location formatted as an s3 url.
     */
    public String asUrl() {
        return "s3://" + bucket + "/" + key;
    }

    /**
     * @return this location formatted as an s3 url with an additional suffix.
     */
    public String asUrlWithSuffix(String suffix) {
        return asUrl() + "/" + suffix;
    }

    /**
     * @return a new S3Location with an additional suffix added to the key
     */
    public S3Location withSuffix(String suffix) {
        if (suffix == null) {
            throw new IllegalArgumentException("suffix cannot be null");
        }

        if (key.isEmpty()) {
            return new S3Location(this.bucket, suffix);
        } else {
            return new S3Location(this.bucket, this.key + "/" + suffix);
        }
    }

    @Override
    public String toString() {
        return "S3Location{" +
            "bucket='" + bucket + '\'' +
            ", key='" + key + '\'' +
            '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        S3Location that = (S3Location) o;

        return bucket.equals(that.bucket) && key.equals(that.key);
    }

    @Override
    public int hashCode() {
        return 31 * bucket.hashCode() + key.hashCode();
    }
}