Java NIO Asynchronous
NIO also provisions asynchronous channel as well.
Path path = Paths.get("README.md");
// this will create asynchronous enabled channel
// other channel like Socket also has this feature
AsynchronousFileChannel c = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
Future
// we read and write data like this, but they return Future object instead
Future<Integer> operation = fileChannel.read(buffer, 0);
Future<Integer> operation = fileChannel.write(buffer, position);
// then we poke around to see if this operation is completed
while(!operation.isDone());
CompletionHandler
Same usage as comparator, simply use CompletionHandler to deal with read and write operation.
Upon read/write completion, the completed method will be invoked.
//
// read
//
c.read(buffer, position, buffer, new CompletionHandler<Integer, ByteBuffer>() {
@Override
public void completed(Integer result, ByteBuffer attachment) {
System.out.println("result = " + result);
attachment.flip();
byte[] data = new byte[attachment.limit()];
attachment.get(data);
System.out.println(new String(data));
attachment.clear();
}
@Override
public void failed(Throwable exc, ByteBuffer attachment) {}
});
//
// write
//
c.write(buffer, position, buffer, new CompletionHandler<Integer, ByteBuffer>() {
@Override
public void completed(Integer result, ByteBuffer attachment) {
System.out.println("bytes written: " + result);
}
@Override
public void failed(Throwable exc, ByteBuffer attachment) {
System.out.println("Write failed");
exc.printStackTrace();
}
});