Examples with AsynchronousFileChannel java.nio.channels.AsynchronousFileChannel used on opensource projects

Example 11 with AsynchronousFileChannel

use of java.nio.channels.AsynchronousFileChannel in project Gargoyle by callakrsos.

the class FileUtil method asynchRead.

public static <T> void asynchRead(Path path, Function<byte[], T> handler) throws IOException {
    AsynchronousFileChannel open = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
    // ByteBuffer 크기를 8k로 축소
    ByteBuffer byteBuffer = ByteBuffer.allocate(8 * 1024);
    long position = 0L;
    Long attachment = 0L;
    long fileSize = open.size();
    open.read(byteBuffer, position, attachment, new CompletionHandler<Integer, Long>() {

        @Override
        public void completed(Integer result, Long attachment) {
            if (result == -1)
                close();
            // 읽기 쓰기 병행시 flip을 호출해줘야함.
            byteBuffer.flip();
            byteBuffer.mark();
            handler.apply(byteBuffer.array());
            byteBuffer.reset();
            // 버퍼 사이즈보다 작다면 파일의 끝까지 읽은 것이므로 종료 처리
            if (result == fileSize || result < byteBuffer.capacity()) {
                //// asyncFileChannel 닫기
                close();
                return;
            }
            // 읽을 내용이 남아있으므로 반복 회수를 증가 시키고 다시 읽는다.
            attachment++;
            open.read(byteBuffer, result * attachment, attachment, this);
        }

        @Override
        public void failed(Throwable exc, Long attachment) {
            exc.printStackTrace();
            close();
        }

        public void close() {
            try {
                if (open != null)
                    open.close();
            } catch (IOException e) {
                throw new RuntimeException(e.getMessage());
            }
        }
    });
}