http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/003295073abf zeigt uns in Java 9 endlich eine lang erwartete Methode:
+ /**
+ * Reads all bytes from this input stream and writes the bytes to the
+ * given output stream in the order that they are read. On return, this
+ * input stream will be at end of stream. This method does not close either
+ * stream.
+ * <p>
+ * This method may block indefinitely reading from the input stream, or
+ * writing to the output stream. The behavior for the case where the input
+ * and/or output stream is <i>asynchronously closed</i>, or the thread
+ * interrupted during the transfer, is highly input and output stream
+ * specific, and therefore not specified.
+ * <p>
+ * If an I/O error occurs reading from the input stream or writing to the
+ * output stream, then it may do so after some bytes have been read or
+ * written. Consequently the input stream may not be at end of stream and
+ * one, or both, streams may be in an inconsistent state. It is strongly
+ * recommended that both streams be promptly closed if an I/O error occurs.
+ *
+ * @param out the output stream, non-null
+ * @return the number of bytes transferred
+ * @throws IOException if an I/O error occurs when reading or writing
+ * @throws NullPointerException if {@code out} is {@code null}
+ *
+ * @since 1.9
+ */
+ public long transferTo(OutputStream out) throws IOException {
+ Objects.requireNonNull(out, "out");
+ long transferred = 0;
+ byte[] buffer = new byte[TRANSFER_BUFFER_SIZE];
+ int read;
+ while ((read = this.read(buffer, 0, TRANSFER_BUFFER_SIZE)) >= 0) {
+ out.write(buffer, 0, read);
+ transferred += read;
+ }
+ return transferred;
+ }