Class FileSource

core/src/main/java/org/apache/calcite/util/Sources.java:169–363

Implementation of Source on the top of a File or URL.

  /** Implementation of {@link Source} on the top of a {@link File} or
   * {@link URL}. */
  private static class FileSource implements Source {
    private final @Nullable File file;
    private final URL url;

    /**
     * A flag indicating if the url is deduced from the file object.
     */
    private final boolean urlGenerated;

    private FileSource(URL url) {
      this.url = requireNonNull(url, "url");
      this.file = urlToFile(url);
      this.urlGenerated = false;
    }

    private FileSource(File file) {
      this.file = requireNonNull(file, "file");
      this.url = fileToUrl(file);
      this.urlGenerated = true;
    }

    private File fileNonNull() {
      return requireNonNull(file, "file");
    }

    private static @Nullable File urlToFile(URL url) {
      if (!"file".equals(url.getProtocol())) {
        return null;
      }
      URI uri;
      try {
        uri = url.toURI();
      } catch (URISyntaxException e) {
        throw new IllegalArgumentException("Unable to convert URL " + url + " to URI", e);
      }
      if (uri.isOpaque()) {
        // It is like file:test%20file.c++
        // getSchemeSpecificPart would return "test file.c++"
        return new File(uri.getSchemeSpecificPart());
      }
      // See https://stackoverflow.com/a/17870390/1261287
      return Paths.get(uri).toFile();
    }

    private static URL fileToUrl(File file) {
      String filePath = file.getPath();
      if (!file.isAbsolute()) {
        // convert relative file paths
        filePath = filePath.replace(File.separatorChar, '/');
        if (file.isDirectory() && !filePath.endsWith("/")) {
          filePath += "/";
        }
        try {
          // We need to encode path. For instance, " " should become "%20"
          // That is why java.net.URLEncoder.encode(java.lang.String, java.lang.String) is not
          // suitable because it replaces " " with "+".
          String encodedPath = new URI(null, null, filePath, null).getRawPath();
          return URI.create("file:" + encodedPath).toURL();