php 爬取超链接

<?php
//$page=file_get_contents("http://www.kmycjng.com/lsmdcx.aspx?sheng=4C26F8901DC98154&c=D39BF6B55B1AA80F");
//preg_match();

header("Content-type: text/html;charset=utf-8");
//连接数据库
$link = mysqli_connect("localhost", "root", "root");
mysqli_select_db("crawler");
mysqli_query(‘set names utf8‘);

function crawler($url)
{
    $contents = file_get_contents($url);
    $content = iconv("gb2312", "utf-8", $contents);

    $data1 = preg_replace("‘([\r\n])[\s]+‘", "", $content);
    preg_match(‘/<h1>(.*?)<\/h1>/‘, $data1, $arr);
    $title = $arr[1];  //标题
    $sql = "SELECT * FROM links WHERE url =‘{$url}‘";
    $result = mysqli_query($sql);
    $row = mysqli_fetch_array($result);
    if ($row) {
        $sqlr = "UPDATE links SET status=1 , title=‘{$title}‘ WHERE id = {$row[‘id‘]}";
    } else {
        $sqlr = "INSERT INTO links(url,title) VALUES (‘$url‘,‘$title‘)";
    }
    $result = mysqli_query($sqlr);

    //获取页面所有连接
    $pattern = "/< a href=\"(.*?)\"/";
    preg_match_all($pattern, $content, $matches);

    $links = $matches[1];
    foreach ($links as $value) {
        $sql = "SELECT * FROM links WHERE url =‘{$value}‘";
        $result = mysqli_query($sql);
        $row = mysqli_fetch_array($result);
        if (!$row) {
            $sqls = "INSERT INTO links(url) VALUES (‘$value‘)";
            $result = mysqli_query($sqls);
        }
    }

    //先查当前url，并写入数据
    //再把当前页面找到的url写入表
}

$url = "http://www.xingwei.edu.cn/";
while (true) {
    crawler($url);
    //获取数据表中没有爬取的连接
    $sql = "SELECT * FROM links WHERE status = 0 order by id asc LIMIT 1";
    $result = mysqli_query($sql);
    $row = mysqli_fetch_array($result);
    if (!$row) {
        break;
    } else {
        $url = $row[‘url‘];
    }
}