Writables.java 文件源码

/**
 * Set bytes into the passed Writable by calling its
 * {@link Writable#readFields(java.io.DataInput)}.
 * @param bytes serialized bytes
 * @param offset offset into array
 * @param length length of data
 * @param w An empty Writable (usually made by calling the null-arg
 * constructor).
 * @return The passed Writable after its readFields has been called fed
 * by the passed <code>bytes</code> array or IllegalArgumentException
 * if passed null or an empty <code>bytes</code> array.
 * @throws IOException e
 * @throws IllegalArgumentException
 */
public static Writable getWritable(final byte [] bytes, final int offset,
  final int length, final Writable w)
throws IOException {
  if (bytes == null || length <=0) {
    throw new IllegalArgumentException("Can't build a writable with empty " +
      "bytes array");
  }
  if (w == null) {
    throw new IllegalArgumentException("Writable cannot be null");
  }
  DataInputBuffer in = new DataInputBuffer();
  try {
    in.reset(bytes, offset, length);
    w.readFields(in);
    return w;
  } finally {
    in.close();
  }
}