修复getDescriptionFromContent 不存在的问题

app/admin/common.php

@@ -25,7 +25,26 @@ function get_login_admin($key = "")
         return '';
     }
 }
-
+/**
+ * 截取摘要
+ *  @return bool
+ */
+function getDescriptionFromContent($content, $count)
+{
+    $content = preg_replace("@<script(.*?)</script>@is", "", $content);
+    $content = preg_replace("@<iframe(.*?)</iframe>@is", "", $content);
+    $content = preg_replace("@<style(.*?)</style>@is", "", $content);
+    $content = preg_replace("@<(.*?)>@is", "", $content);
+    $content = str_replace(PHP_EOL, '', $content);
+    $space = array(" ", "　", "  ", " ", " ");
+    $go_away = array("", "", "", "", "");
+    $content = str_replace($space, $go_away, $content);
+    $res = mb_substr($content, 0, $count, 'UTF-8');
+    if (mb_strlen($content, 'UTF-8') > $count) {
+        $res = $res . "...";
+    }
+    return $res;
+}
 /**
  * PHP格式化字节大小
  * @param number $size      字节数