public class Directory{
    private String file;
    
    public Directory(String filePath){
        setFile(filePath);
    }

    public String getFile() {
        return this.file;
    }

    public void setFile(String filePath) {
        try {
            FileInputStream in = new FileInputStream(new File("filePath"));
            FileChannel fileChannel = in.getChannel();

            MappedByteBuffer mappedByteBuffer = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0,
                    fileChannel.size());

            byte[] bytes = new byte[(int) fileChannel.size()];
            mappedByteBuffer.get(bytes);
            //这里我只是简单的举例处理数据
            //假设源文件是文本文件，文件内都是算法加密的文本
            //假设有一个算法类Algorithm类有个静态decrypt方法用来还原加密文本
            String file = Algorithm.decrypt(bytes.toString());
            this.file = file;
        } catch (FileNotFoundException e1) {
            e1.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }
}