为什么fileChannel.read循环永远不会结束？

import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class FileReadExample {
    public static void main(String[] args) {
        try (FileInputStream fis = new FileInputStream("example.txt");
             FileChannel channel = fis.getChannel()) {
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int bytesRead;
            while ((bytesRead = channel.read(buffer)) != -1) {
                buffer.flip();
                // 处理读取到的数据
                while (buffer.hasRemaining()) {
                    System.out.print((char) buffer.get());
                }
                buffer.clear();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}