PHP实现简单爬虫-抓取网页url

<?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();

?>