php自动给文章加关键词链接的实现代码

<?php
/**
* 添加文章关键词，内链
* by www.jbxue.com
*/
$link = array(
‘百度,http://www.baidu.com/’,
‘dedecms,http://www.jbxue.com/’,
);
$str = ‘在百度中搜索dedecms’;
$out = keylink ( $str, $link, 1 );
//$str 原始字符 $link，替换链接数组, 3替换次数
echo $out;
function _sortDesc($a, $b) {
return (strlen ( $a [0] ) < strlen ( $b [0] )) ? 1 : – 1;
}
function keylink($str, $link, $count = 1) {
$linkDefs = $link;
$linkMap = array ();
foreach ( $linkDefs as $row ) {
$linkMap [] = explode ( ‘,’, $row );
}
foreach ( $linkMap as $row ) {
$str = preg_replace ( ‘/(s*)(‘ . $row [0] . ‘)(s*</a>)/sui’, ‘${2}’, $str );
}
usort ( $linkMap, ‘_sortDesc’ );
$tmpKwds = array ();
foreach ( $linkMap as $i => $row )
{
list ( $kwd, $url ) = $row;
for($j = $i + 1; $j < count ( $linkMap ); $j ++)
{
$subKwd = $linkMap [$j] [0];
//如果包含其他关键字，暂时替换成其他字符串
if (strpos ( $kwd, $subKwd ) !== false)
{
$tmpKwd = ‘{‘ . md5 ( $subKwd ) . ‘}’;
$kwd = str_replace ( $subKwd, $tmpKwd, $kwd );
$tmpKwds [$tmpKwd] = $subKwd;
}
}
//把文字替换成链接
$str = preg_replace ( ‘/(‘ . $row [0] . ‘)/sui’, ‘<a href=”‘ . $row [1] . ‘” target=”_blank”>’ . $kwd . ‘</a>’, $str, $count );
}
//把代替子关键字的字符串替换回来
foreach ( $tmpKwds as $tmp => $kwd ) {
$str = str_replace ( $tmp, $kwd, $str );
}
return $str;
}
?>