Class Resources

corpus/java/training/guava/io/Resources.java:46–214

Provides utility methods for working with resources in the classpath. Note that even though these methods use URL parameters, they are usually not appropriate for HTTP or other non-classpath resources. All method parameters must be non-null unless documented otherwise. @author Chris Nok

 * @since 1.0
 */
@Beta
@GwtIncompatible
public final class Resources {
  private Resources() {}

  /**
   * Returns a {@link ByteSource} that reads from the given URL.
   *
   * @since 14.0
   */
  public static ByteSource asByteSource(URL url) {
    return new UrlByteSource(url);
  }

  /**
   * A byte source that reads from a URL using {@link URL#openStream()}.
   */
  private static final class UrlByteSource extends ByteSource {

    private final URL url;

    private UrlByteSource(URL url) {
      this.url = checkNotNull(url);
    }

    @Override
    public InputStream openStream() throws IOException {
      return url.openStream();
    }

    @Override
    public String toString() {
      return "Resources.asByteSource(" + url + ")";
    }
  }

  /**
   * Returns a {@link CharSource} that reads from the given URL using the given character set.
   *
   * @since 14.0
   */
  public static CharSource asCharSource(URL url, Charset charset) {
    return asByteSource(url).asCharSource(charset);
  }

  /**
   * Reads all bytes from a URL into a byte array.
   *
   * @param url the URL to read from
   * @return a byte array containing all the bytes from the URL
   * @throws IOException if an I/O error occurs
   */
  public static byte[] toByteArray(URL url) throws IOException {
    return asByteSource(url).read();
  }

  /**
   * Reads all characters from a URL into a {@link String}, using the given character set.