Compression.java

// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.io;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.util.zip.GZIPOutputStream;
import java.util.zip.ZipOutputStream;

import org.apache.commons.compress.compressors.bzip2.BZip2CompressorOutputStream;
import org.openstreetmap.josm.tools.Utils;

/**
 * An enum representing the compression type of a resource.
 */
public enum Compression {
    /**
     * no compression
     */
    NONE,
    /**
     * bzip2 compression
     */
    BZIP2,
    /**
     * gzip compression
     */
    GZIP,
    /**
     * zip compression
     */
    ZIP;

    /**
     * Determines the compression type depending on the suffix of {@code name}.
     * @param name File name including extension
     * @return the compression type
     */
    public static Compression byExtension(String name) {
        return name != null && name.endsWith(".gz")
                ? GZIP
                : name != null && (name.endsWith(".bz2") || name.endsWith(".bz"))
                ? BZIP2
                : name != null && name.endsWith(".zip")
                ? ZIP
                : NONE;
    }

    /**
     * Determines the compression type based on the content type (MIME type).
     * @param contentType the content type
     * @return the compression type
     */
    public static Compression forContentType(String contentType) {
        switch (contentType) {
        case "application/zip":
            return ZIP;
        case "application/x-gzip":
            return GZIP;
        case "application/x-bzip2":
            return BZIP2;
        default:
            return NONE;
        }
    }

    /**
     * Returns an un-compressing {@link InputStream} for {@code in}.
     * @param in raw input stream
     * @return un-compressing input stream
     *
     * @throws IOException if any I/O error occurs
     */
    public InputStream getUncompressedInputStream(InputStream in) throws IOException {
        switch (this) {
            case BZIP2:
                return Utils.getBZip2InputStream(in);
            case GZIP:
                return Utils.getGZipInputStream(in);
            case ZIP:
                return Utils.getZipInputStream(in);
            case NONE:
            default:
                return in;
        }
    }

    /**
     * Returns an un-compressing {@link InputStream} for the {@link File} {@code file}.
     * @param file file
     * @return un-compressing input stream
     * @throws IOException if any I/O error occurs
     */
    public static InputStream getUncompressedFileInputStream(File file) throws IOException {
        FileInputStream in = new FileInputStream(file);
        try {
            return byExtension(file.getName()).getUncompressedInputStream(in);
        } catch (IOException e) {
            Utils.close(in);
            throw e;
        }
    }

    /**
     * Returns a compressing {@link OutputStream} for {@code out}.
     * @param out raw output stream
     * @return compressing output stream
     *
     * @throws IOException if any I/O error occurs
     */
    public OutputStream getCompressedOutputStream(OutputStream out) throws IOException {
        switch (this) {
            case BZIP2:
                return new BZip2CompressorOutputStream(out);
            case GZIP:
                return new GZIPOutputStream(out);
            case ZIP:
                return new ZipOutputStream(out, StandardCharsets.UTF_8);
            case NONE:
            default:
                return out;
        }
    }

    /**
     * Returns a compressing {@link OutputStream} for the {@link File} {@code file}.
     * @param file file
     * @return compressing output stream
     *
     * @throws IOException if any I/O error occurs
     */
    public static OutputStream getCompressedFileOutputStream(File file) throws IOException {
        FileOutputStream out = new FileOutputStream(file);
        try {
            return byExtension(file.getName()).getCompressedOutputStream(out);
        } catch (IOException e) {
            Utils.close(out);
            throw e;
        }
    }
}