Merge branch 'master' into 'master'

修改mongodb选择集合的方式

See merge request !12

@@ -261,12 +261,12 @@ class MongoCore extends Root
      * @param $collection
      * @return \MongoCollection
      */
-    public function selectCollection($dbname, $collection)
+    public function selectCollection($collection)
     {
         if ($this->_mongo == null) {
-            $this->_connect($dbname);
+            $this->_connect($this->_dbname);
         }
-        return $this->_mongo->selectCollection($dbname, $collection);
+        return $this->collection($this->_dbname,$collection);
     }
 
     /**