使用BufferedInputStream和BufferedOutputStream编写程序，实现文件的复制。(如将D 盘m.txt文件的内容复制到D盘n.txt文件中

当你需要在Java中使用`BufferedInputStream`和`BufferedOutputStream`来复制文件时，你可以按照以下步骤操作：

1. 首先，创建一个`BufferedReader`和一个`BufferedWriter`对象，分别用于读取输入流和写入输出流。这两个类都是对标准的`InputStreamReader`和`OutputStreamWriter`进行了缓冲处理。

FileInputStream fis = new FileInputStream("D:\\m.txt");
BufferedReader in = new BufferedReader(new InputStreamReader(fis, StandardCharsets.UTF_8));
FileOutputStream fos = new FileOutputStream("D:\\n.txt");
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(fos, StandardCharsets.UTF_8));

2. 使用循环逐行读取输入文件，并将其写入输出文件。这通常涉及到一行接一行地从`BufferedReader`读取，然后存储到`BufferedWriter`中。

String line;
while ((line = in.readLine()) != null) {
    out.write(line);
    out.newLine(); // 每写一行后换行
}

3. 最后关闭两个流，释放资源。

in.close();
out.close();
fis.close();
fos.close();

完整的代码示例如下：

import java.io.*;

public class FileCopyExample {
    public static void main(String[] args) {
        try {
            FileInputStream fis = new FileInputStream("D:\\m.txt");
            BufferedReader in = new BufferedReader(new InputStreamReader(fis, StandardCharsets.UTF_8));
            FileOutputStream fos = new FileOutputStream("D:\\n.txt");
            BufferedWriter out = new BufferedWriter(new OutputStreamWriter(fos, StandardCharsets.UTF_8));

            String line;
            while ((line = in.readLine()) != null) {
                out.write(line);
                out.newLine();
            }

            in.close();
            out.close();
            fis.close();
            fos.close();

            System.out.println("File copy completed successfully.");
        } catch (IOException e) {
            System.err.println("Error occurred during file copy: " + e.getMessage());
        }
    }
}