Creating an input or output stream on a ByteBuffer : InputStream « File « Java Tutorial

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2. File
3. InputStream

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;

public class Main {
  public static void main(String[] argv) throws Exception {
    ByteBuffer buf = ByteBuffer.allocate(10);
    OutputStream os = new ByteBufferBackedOutputStream(buf);
    InputStream is = new  ByteBufferBackedInputStream(buf);
  }

}
class ByteBufferBackedInputStream extends InputStream{
  
  ByteBuffer buf;
  ByteBufferBackedInputStream( ByteBuffer buf){
    this.buf = buf;
  }
  public synchronized int read() throws IOException {
    if (!buf.hasRemaining()) {
      return -1;
    }
    return buf.get();
  }
  public synchronized int read(byte[] bytes, int off, int len) throws IOException {
    len = Math.min(len, buf.remaining());
    buf.get(bytes, off, len);
    return len;
  }
}
class ByteBufferBackedOutputStream extends OutputStream{
  ByteBuffer buf;
  ByteBufferBackedOutputStream( ByteBuffer buf){
    this.buf = buf;
  }
  public synchronized void write(int b) throws IOException {
    buf.put((byte) b);
  }

  public synchronized void write(byte[] bytes, int off, int len) throws IOException {
    buf.put(bytes, off, len);
  }
  
}