回答

我们以php为例实现一个自定义的二进制文件数据库，通过pack与unpack格式化数据进行存储，示例如下：

<?php

class Person_Data

{

    /**

    * 数据库文件路径

    *

    * @var string

    */

    var $_database = 'wps.db';

    /**

    * 打开一个数据库文件

    *

    * @param string $file 数据库文件名

    */

    function openDb($file = 'wps.db') {

        $this->_database = $file;

        $this->_database = fopen($this->_database, 'ab+');

    }

    /**

    * 向数据库中写入一条记录

    *

    * @param array $data 

    * @return void

    */

    function writeRecord($data) {

        $name = pack('a8', $data['name']);

        $age = pack('S', $data['age']);

        $email = pack('a30', $data['email']);

        fwrite($this->_database, $name . $age . $email);

    }

    /**

    * 读取一条记录

    *

    * @param int $count optional default to 0 记录id数

    * @return array

    */

    function read($count = 0) {

        rewind($this->_database);

        fseek($this->_database, 40 * $count);

        $return = array();

        $return['name'] = unpack('a8', fread($this->_database, 8));

        $return['name'] = $return['name'][1];

        $return['age'] = unpack('S', fread($this->_database, 2));

        $return['age'] = $return['age'][1];

        $return['email'] = unpack('a30', fread($this->_database, 30));

        $return['email'] = $return['email'][1];

        return $return;

    }

}

$me = array('name' => '张涛',
    'age' => 23,
    'email' => 'bfw@bfw.wiki');
$data = new Person_Data();
$data->openDb('wps.db');
$data->writeRecord($me);
print_r($data->read(1));