如果我使用 ReadableByteChannel 和 BufferedReader，如何读取 InputStream 两次？

Question

How to read an InputStream twice if I am using ReadableByteChannel and BufferedReader ?

Here is my code:

ReadableByteChannel inputChannel = Channels.newChannel(input);
WritableByteChannel outputChannel = Channels.newChannel(output);

InputStream ind = Channels.newInputStream(inputChannel);
ReadableByteChannel inputChannel1 = Channels.newChannel(ind);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
org.apache.commons.io.IOUtils.copy(ind, baos);
ByteBuffer buffer = ByteBuffer.allocateDirect(10240);
long size = 0;
while (inputChannel1.read(buffer) != -1) {
    buffer.flip();
    size += outputChannel.write(buffer);
    buffer.clear();
}

byte[] bytes = baos.toByteArray();
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
BufferedReader in = new BufferedReader(new InputStreamReader(bais));
String inputLine;
StringBuffer bufferResponse = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
    bufferResponse.append(inputLine);
}
JSONObject jsonResponse = new JSONObject(bufferResponse.toString());

Answer 1

You've written a lot of code to copy input to two destinations: output and jsonResponse . As you have made an in-memory copy of input => bytes there is no need to scan input twice, and you don't need to use IOUtils for a simple copy to byte[] which you can re-use to send to the two destinations:

ByteArrayOutputStream baos = new ByteArrayOutputStream();
input.transferTo(baos);
byte[] bytes = baos.toByteArray();
output.write(bytes);

Then do as @g00se suggests - if the char encoding is platform default:

String s = new String(bytes /*, or insert another charset here */);
JSONObject jsonResponse = new JSONObject(s);

You should also deal with closing the input/output streams, best done with try-with-resources block.