如何将我的servlet从另一个类连接到boolean方法？

Question

我尝试了一些变体，并且我当然导入了包含我在Servlet中使用的布尔方法的类，但无论如何它都看不到该方法。

这是我的班级登录方法：

        MyCon = Database.getConnection();
        boolean result = false;
        Statement statement = null;
        ResultSet resultSet = null;



        try {
            String sql = "SELECT * FROM input_form WHERE username ='"+username+"'AND password='"+password+"'";
            statement=MyCon.createStatement();
            resultSet = statement.executeQuery(sql);
            if (resultSet.next()) {
                result=true;
            }else {
                result = false;

            }
        } catch (SQLException e) {



        }
        return result;


    }

} ```

And when i need to access that method in servlet, it doesnt see it :

 ```protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String username = request.getParameter("username");
        String password = request.getParameter("password");

        response.setContentType("text/html/charset-UTF-8");
        out =response.getWriter();

        boolean login = processLogin(username,password);  //this is where it doesnt see it

         ```

what could i do for my servlet to see the method?

Answer 1

创建您需要调用的类的object，然后使用该object来调用所需的方法。因此，您的doPost方法将如下所示：

    String username = request.getParameter("username");
    String password = request.getParameter("password");
    response.setContentType("text/html/charset-UTF-8");
    out =response.getWriter();
    Login l1 =new Login();//creating object of class
    boolean login = l1.processLogin(username,password); //using object to call the method
   //do further process

另外，使用PreparedStatement选择数据库中的值并避免使用任何SQL injection。因此，您的方法代码如下所示：

PreparedStatement ps = con.prepareStatement("select *from input_form where username=? AND password= ?");
    ps.setString(1, username);
    ps.setString(2, password);
    ResultSet rs = ps.executeQuery();
    //if true
    if (rs.next()) {
    result=true;
    }else{
     result = false;
    }