利用IO实现文件复制：

public static void main(String[] args) {
        File source = new File("C:/Users/86189/Pictures/clipboard.png");
        File target = new File("C:/Users/86189/Pictures/clipboard1.png");
        InputStream is = null;
        OutputStream os = null;
        try {
            is = new FileInputStream(source);
            os = new FileOutputStream(target);
            byte[] b = new byte[1024];
            int n = 0;
            while ((n = is.read(b)) != -1) {
                os.write(b, 0, n);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                is.close();
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

FileChannel实现文件复制：（fileChannel是专门用于文件读写的通道，效率更高，使用更简单）

Commens IO组件实现文件复制。。是apach提供的第三方开源包