原生JAVA-nio FileChannel Demo

public class TestNio {

    public static void main(String[] args) throws IOException {
        writeFileChannel();
    }

    //fileChannel读文件
    public static void testFileChannel() throws IOException {
        // fileChannel
        RandomAccessFile aFile = new RandomAccessFile(new File("d:\java-2021-03.7z"), "rw");
        FileChannel channel = aFile.getChannel();
        // 缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);
        // 读数据进缓冲区
        int bytesRead = channel.read(buf);
        while (bytesRead != -1) {
            System.out.println("file长度:" + bytesRead);
            buf.flip();
            while (buf.hasRemaining()) {
                System.out.println((char) buf.get());
            }
            buf.clear();
            bytesRead = channel.read(buf);
        }
        aFile.close();
        System.out.println("end");
    }

    //fileChannel写文件
    public static void writeFileChannel() throws IOException{
        RandomAccessFile rw = new RandomAccessFile("d:\fx.txt", "rw");
        FileChannel channel = rw.getChannel();
        ByteBuffer buf = ByteBuffer.allocate(1024);
        buf.put("你说过不闪躲，你非要这么做。".getBytes(StandardCharsets.UTF_8));
        buf.flip();
        while (buf.hasRemaining()) {
            channel.write(buf);
        }
        channel.close();
    }

//fileChannel通道之间传输
public static void testFileChannelTransfer() throws IOException{
    RandomAccessFile aFile = new RandomAccessFile("d:\aa.txt", "rw");
    FileChannel channelFrom = aFile.getChannel();
    RandomAccessFile bFile = new RandomAccessFile("d:\fx.txt", "rw");
    FileChannel channelTo = bFile.getChannel();
    //from 的内容传输到 channelTo
    channelTo.transferFrom(channelFrom, 0, channelFrom.size());
    aFile.close();
    bFile.close();
}

}