致命错误：未捕获错误：调用/opt/lampp/htdocs/apms/class/news.php中未定义的方法Dbconnection :: prepare（）

Question

当我调用PDO函数时，它向我显示此错误：

  

致命错误：未捕获错误：调用未定义的方法Dbconnection :: prepare（）
  在/opt/lampp/htdocs/apms/class/news.php:18
中   堆栈跟踪：
  ＃0 /opt/lampp/htdocs/apms/class/news.php(30）：新闻-> fetch_news_content（）
  ＃1 {main}在第18行的/opt/lampp/htdocs/apms/class/news.php中抛出

这是我的联系班：

class Dbconnection
{
    private $servername = "localhost";
    private $username = "root";
    private $password = "";
    protected $conn;
    public function connect()
    {
        try {
            $conn = new PDO("mysql:host=$this->servername;dbname=apms", $this->username, $this->password);
            $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            return $this->conn;
        } catch (PDOException $e) {
            echo "Connection failed: " . $e->getMessage();
        }
    }
}