DataReader and DataWriter

DataReader consumes an InputStream; DataWriter writes bytes or an input stream to an OutputStream.

String text = new DataReader(inputStream).readAsString();

ByteArrayOutputStream output = new ByteArrayOutputStream();
new DataWriter(output).write("hello".getBytes(StandardCharsets.UTF_8));

DataReader closes its input stream after readStreamAsBytes, readAsLineString, readAsString, or readAsBytes. Do not reuse the input afterward. DataWriter flushes but does not close its output stream; this makes it suitable for writing to a caller-owned response, file, or in-memory stream. Its default buffering can be changed with setBuffered(boolean).

readStreamAsBytes(int, BiConsumer<Integer, byte[]>) passes the number of valid bytes together with a reusable buffer; consume only the range [0, readSize) before the next callback.