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Monday March 27, 2006

Using database in Enterprise application client module. In my last post the new Netbeans project type was presented. Today, I would like to use this project and show how a database connection can be developed in Enterprise application client very simple. Let's start to create application that lists customers that are stored in database.

• Create new Enterprise Application client project
• Add new JFrame with name DisplayCustomernames in the project. In the form put JTable

• Open project's properties panel and set this class as main class in the application
• Open JFrame in source editor. Now, we should inject DataSource and creat table model
• Injected property should be in Main class and should be static. We will use default JDBC resource in Glassfish that has a name jdbc/__deafult. Add these lines at beginning of the class:

          @Resource(name="jdbc/__default")
          private static DataSource ds;
       

• Then, create Customer class that represents customer entity in database. This isn't needed in small application. Create new class Customer with id, name and email properties. Create set/get methods for these fields.
• Create a model for JTable. Add new CustomerTblModel class that implements TableModel. In constructor add method that reads data from database:

        private void readData() {
          Connection conn = null;
          try{
          conn = ds.getConnection();
          PreparedStatement pStmt = 
               conn.prepareStatement("SELECT CUSTOMER_ID, NAME, EMAIL FROM CUSTOMER");
          ResultSet rs = pStmt.executeQuery();
          while(rs.next()){
              custs.add(new Customer(rs.getInt(1), rs.getString(2), rs.getString(3)));
          }
          }catch(SQLException ex) {
              throw new RuntimeException(ex);
          }finally {
              if(conn != null) {
                  try {
                  conn.close();
                  } catch(SQLException ex) { }
              }
          }
      }
     

• Don't forget set the table model in JFrame constructor after initComponents method:

        public DisplayCustomerNames() {
          initComponents();
          cstTableModel = new CustomerTableModel(ds);
          jTable1.setModel(cstTableModel);
      }
     
   

• Run project.