如何使用Java NIO框架有效地从大文件读取并将大数据写入文件。

我工作ByteBuffer，并FileChannel和曾尝试类似如下：

public static void main(String[] args) 
{
    String inFileStr = "screen.png";
    String outFileStr = "screen-out.png";
    long startTime, elapsedTime; 
    int bufferSizeKB = 4;
    int bufferSize = bufferSizeKB * 1024;

    // Check file length
    File fileIn = new File(inFileStr);
    System.out.println("File size is " + fileIn.length() + " bytes");
    System.out.println("Buffer size is " + bufferSizeKB + " KB");
    System.out.println("Using FileChannel with an indirect ByteBuffer of " + bufferSizeKB + " KB");

    try (   FileChannel in = new FileInputStream(inFileStr).getChannel();
            FileChannel out = new FileOutputStream(outFileStr).getChannel() ) 
    {
        // Allocate an indirect ByteBuffer
        ByteBuffer bytebuf = ByteBuffer.allocate(bufferSize);

        startTime = System.nanoTime();

        int bytesCount = 0;
        // Read data from file into ByteBuffer
        while ((bytesCount = in.read(bytebuf)) > 0) { 
            // flip the buffer which set the limit to current position, and position to 0.
            bytebuf.flip();
            out.write(bytebuf); // Write data from ByteBuffer to file
            bytebuf.clear(); // For the next read
        }

        elapsedTime = System.nanoTime() - startTime;
        System.out.println("Elapsed Time is " + (elapsedTime / 1000000.0) + " msec");
    } 
    catch (IOException ex) {
        ex.printStackTrace();
    }
}

谁能告诉我，如果我的文件大小超过2 GB，我应该遵循相同的步骤吗？

如果大量的书面操作，我想在写作时做类似的事情，该怎么办？