PHP实现简单爬虫

<?php

/**

 * 爬虫程序 -- 原型

 *

 * 从给定的url获取html内容

 *

 * @param string $url

 * @return string

 */

function _getUrlContent($url) {

    $handle = fopen($url, "r");

    if ($handle) {

        $content = stream_get_contents($handle, 1024 * 1024);

        return $content;

    } else {

        return false;

    }

}

/**

 * 从html内容中筛选链接

 *

 * @param string $web_content

 * @return array

 */

function _filterUrl($web_content) {

    $reg_tag_a = '/<[a|A].*?href=[\'\"]{0,1}([^>\'\"\ ]*).*?>/';

    $result = preg_match_all($reg_tag_a, $web_content, $match_result);

    if ($result) {

        return $match_result[1];

    }

}

/**

 * 修正相对路径

 *

 * @param string $base_url

 * @param array $url_list

 * @return array

 */

function _reviseUrl($base_url, $url_list) {

    $url_info = parse_url($base_url);

    $base_url = $url_info["scheme"] . '://';

    if ($url_info["user"] && $url_info["pass"]) {

        $base_url .= $url_info["user"] . ":" . $url_info["pass"] . "@";

    }

    $base_url .= $url_info["host"];

    if ($url_info["port"]) {

        $base_url .= ":" . $url_info["port"];

    }

    $base_url .= $url_info["path"];

    print_r($base_url);

    if (is_array($url_list)) {

        foreach ($url_list as $url_item) {

            if (preg_match('/^http/', $url_item)) {

                // 已经是完整的url

                $result[] = $url_item;

            } else {

                // 不完整的url

                $real_url = $base_url . '/' . $url_item;

                $result[] = $real_url;

            }

        }

        return $result;

    } else {

        return;

    }

}

/**

 * 爬虫

 *

 * @param string $url

 * @return array

 */

function crawler($url) {

    $content = _getUrlContent($url);

    if ($content) {

        $url_list = _reviseUrl($url, _filterUrl($content));

        if ($url_list) {

            return $url_list;

        } else {

            return ;

        }

    } else {

        return ;

    }

}

/**

 * 测试用主程序

 */

function main() {

    $current_url = "http://hao123.com/"; //初始url

    $fp_puts = fopen("url.txt", "ab"); //记录url列表

    $fp_gets = fopen("url.txt", "r"); //保存url列表

    do {

        $result_url_arr = crawler($current_url);

        if ($result_url_arr) {

            foreach ($result_url_arr as $url) {

                fputs($fp_puts, $url . "\r\n");

            }

        }

    } while ($current_url = fgets($fp_gets, 1024)); //不断获得url

}

main();

 

?>