Java NIO读取文件数据并输出

原理流程图

源码demo

public static void main(String[] args) throws Exception {
    //拿到文件
    File file = new File("d:\\test\\write.txt");
    FileInputStream inputStream = new FileInputStream(file);
    //创建管道，把文件放入通道
    FileChannel fileChannel = inputStream.getChannel();
    //创建Buffer
    ByteBuffer buffer = ByteBuffer.allocate((int)file.length());
    //从通道读数据放入缓冲区
    fileChannel.read(buffer);
    System.out.println(new String(buffer.array()));
    //关闭与清除
    fileChannel.close();
    inputStream.close();
    buffer.clear();
}

NIO保存数据到文件