unix/linux的Java IO实现"tail -f"

import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

public class TailF {
    public static void main(String[] args) throws IOException {
        String filePath = "/path/to/your/file";
        File file = new File(filePath);

        try (FileChannel fileChannel = FileChannel.open(Paths.get(filePath), StandardOpenOption.READ);
             Selector selector = Selector.open()) {

            fileChannel.position(fileChannel.size());
            fileChannel.register(selector, SelectionKey.OP_READ);

            while (true) {
                selector.select();
                for (SelectionKey key : selector.selectedKeys()) {
                    if (key.isReadable()) {
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        int bytesRead = fileChannel.read(buffer);
                        if (bytesRead > 0) {
                            buffer.flip();
                            System.out.println(new String(buffer.array(), 0, bytesRead));
                        }
                    }
                }
            }
        }
    }
}

import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;

public class TailF {
    public static void main(String[] args) throws IOException {
        String filePath = "/path/to/your/file";
        RandomAccessFile file = new RandomAccessFile(filePath, "r");
        long lastPosition = 0;

        while (true) {
            long currentPosition = file.length();
            if (currentPosition != lastPosition) {
                file.seek(lastPosition);
                byte[] buffer = new byte[(int) (currentPosition - lastPosition)];
                file.read(buffer);
                System.out.println(new String(buffer));
                lastPosition = currentPosition;
            }
            Thread.sleep(1000);
        }
    }
}