java怎么用代码实现复制一个文件夹到另一个文件夹中去

您可以使用以下方法在Java中复制一个文件夹到另一个文件夹中：

public static void copyFolder(File sourceFolder, File destinationFolder) throws IOException {
    if (sourceFolder.isDirectory()) {
        if (!destinationFolder.exists()) {
            destinationFolder.mkdir();
        }

        String[] files = sourceFolder.list();

        if (files != null) {
            for (String file : files) {
                File srcFile = new File(sourceFolder, file);
                File destFile = new File(destinationFolder, file);

                copyFolder(srcFile, destFile);
            }
        }
    } else {
        InputStream in = new FileInputStream(sourceFolder);
        OutputStream out = new FileOutputStream(destinationFolder);

        byte[] buffer = new byte[1024];

        int length;
        while ((length = in.read(buffer)) > 0) {
            out.write(buffer, 0, length);
        }

        in.close();
        out.close();
    }
}

可以调用这个方法来实现复制：

File sourceFolder = new File("path/to/source/folder");
File destinationFolder = new File("path/to/destination/folder");

copyFolder(sourceFolder, destinationFolder);

请记得引入必要的 Java IO 包。