将普通链接转为可跳转链接(不完善，使用会存在问题，可借鉴)

public function text2links($str='') {
      if($str=='' or !preg_match('/(http|www\.|@)/i', $str)) { return $str; }
      $lines = explode("\n", $str); $new_text = '';
      while (list($k,$l) = each($lines)) {
        // replace links:
        $l = preg_replace("/([ \t]|^)www\./i", "\\1http://www.", $l);
        $l = preg_replace("/([ \t]|^)ftp\./i", "\\1ftp://ftp.", $l);
        $l = preg_replace("/(http:\/\/[^ )\r\n!]+)/i",
          "<a href=\"\\1\">\\1</a>", $l);
        $l = preg_replace("/(https:\/\/[^ )\r\n!]+)/i",
          "<a href=\"\\1\">\\1</a>", $l);
        $l = preg_replace("/(ftp:\/\/[^ )\r\n!]+)/i",
          "<a href=\"\\1\">\\1</a>", $l);
        $l = preg_replace(
          "/([-a-z0-9_]+(\.[_a-z0-9-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)+))/i",
          "<a href=\"mailto:\\1\">\\1</a>", $l);
        $new_text .= $l."\n";
      }
      return $new_text;
    }

使用：复制方法，然后调用。