CODEWITHSUNDEEP
javajspservlets
Anton Sementsov
Anton Sementsov

Reputation: 1246

Call function from other servlet

I'm writing a blog on Java, now I have have 2 servlets models, in first I write functions to manipulate with articles, and in second to manipulate with categories. When I add new article, I should have all categories in dropdown list on my form. How can I call from my servlet ArticleMod, function getCategoryList() which already placed in CategoryMod servlet;

Here's code of function:

    public Category[] getCategoryList() throws Exception {
    db data = new db();
    Connection con = data.OpenConnection();

    PreparedStatement statement = con.prepareStatement("SELECT * FROM `category`");
    ResultSet result = statement.executeQuery();

    int size = 0;  
    if (result != null)   
    {  
        if (result.last()) {
            size = result.getRow();
            result.beforeFirst();
        }
    }  
    Category[] categories = new Category[size];
    int i = 0;
    while(result.next()){
        categories[i] = new Category (
                result.getInt(1),
                result.getString(2),
                result.getString(3));
        i++;        
    }

    return categories;
   }

on this servlet im use it like that

     if (request.getParameter("todo").equals("show_category_list")) {
         try {
             Category[] categories = this.getCategoryList();

             request.setAttribute("categories", categories);
             RequestDispatcher dispatcher = request.getRequestDispatcher("category/category_list.jsp");
             dispatcher.forward(request, response);
         } catch (Exception e) {
                }
     }

How can I call that function from other servlet?

Upvotes: 1

Views: 2843

Answers (2)

Sam
Sam

Reputation: 6890

You can use a Parent Abstract class for two servlet and putting shared behavior there. for sample see following code:

public abstract class ParentServlet extends HttpServlet
{
    public Category[] getCategoryList() throws Exception
    {
         /**
          * Your getCategoryList codes
          */
    }
}

class ChildServelt_1 extends ParentServlet
{
    @Override
    public void service(ServletRequest arg0,
                        ServletResponse arg1) throws ServletException, IOException
    {
        /*
         * Do write your business
         */
        super.getCategoryList();
    }
}
class ChildServelt_2 extends ParentServlet
{
    @Override
    public void service(ServletRequest arg0,
                        ServletResponse arg1) throws ServletException, IOException
    {
        /*
         * Do write your business
         */
        super.getCategoryList();
    }
}

when two method have shared behavior they are may have a Parent, it is a rule of OOP.

Upvotes: 1

Ernest Friedman-Hill
Ernest Friedman-Hill

Reputation: 81684

Move the method either to a common base class for the two servlets, or to a utility class that both servlets can share. Writing the two servlets to depend arbitrarily on one another this way would be a bad design.

Upvotes: 3

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