Channel (NIO 二)

※non-Direct

try (
    FileChannel in = new FileInputStream("1.jpg").getChannel();
    FileChannel out = new FileOutputStream("2.jpg").getChannel();
) {
    ByteBuffer buffer = ByteBuffer.allocate(1024);
    
    while (in.read(buffer) != -1) {
        buffer.flip();
        out.write(buffer);
        buffer.clear();
    }
    System.out.println("copy complete!");
} catch (IOException e) {
    e.printStackTrace();
}

※

※Direct 使用映射

OpenOption[] oo = { StandardOpenOption.WRITE, StandardOpenOption.READ, StandardOpenOption.CREATE };
try (
        FileChannel in = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
        FileChannel out = FileChannel.open(Paths.get("2.jpg"), oo);
    ) {
    MappedByteBuffer inMap = in.map(MapMode.READ_ONLY, 0, in.size());
    MappedByteBuffer outMap = out.map(MapMode.READ_WRITE, 0, in.size());
    
    byte[] dst = new byte[inMap.limit()];
    inMap.get(dst);
    outMap.put(dst);
    System.out.println("copy complete");
} catch (IOException e) {
    e.printStackTrace();
}

※

※Direct

OpenOption[] oo = { StandardOpenOption.WRITE, StandardOpenOption.READ, StandardOpenOption.CREATE };
try (
        FileChannel in = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
        FileChannel out = FileChannel.open(Paths.get("2.jpg"), oo);
    ) {
    in.transferTo(0, in.size(), out); // in 到 out
    // out.transferFrom(in, 0, in.size()); // out 從 in 過來的
    System.out.println("copy complete");
} catch (IOException e) {
    e.printStackTrace();
}

※