java - Show JDBC ResultSet in HTML in JSP page using MVC and DAO pattern -


i'm implementing mvc using jsp , jdbc. have imported database class file jsp file , show data of db table. don't know how should return resultset java class jsp page , embed in html.

how can achieve this?

in designed mvc approach, jsp file should not contain line of java code , servlet class should not contain line of jdbc code.

assuming want show list of products in webshop, following code needs created.

  • a product class representing real world entity of product, should javabean.

    public class product {      private long id;      private string name;     private string description;     private bigdecimal price;      // add/generate getters/setters/c'tors/equals/hashcode boilerplate. }

  • a dao class nasty jdbc work , returns nice list<product>.

    public class productdao {      private datasource datasource;      public productdao(datasource datasource) {         this.datasource = datasource;     }      public list<product> list() throws sqlexception {         list<product> products = new arraylist<product>();          try (             connection connection = datasource.getconnection();             preparedstatement statement = connection.preparestatement("select id, name, description, price product");             resultset resultset = statement.executequery();         ) {             while (resultset.next()) {                 product product = new product();                 product.setid(resultset.getlong("id"));                 product.setname(resultset.getstring("name"));                 product.setdescription(resultset.getstring("description"));                 product.setprice(resultset.getbigdecimal("price"));                 products.add(product);             }         }          return products;     }  }

  • a servlet class obtains list , puts in request scope.

    @webservlet("/products") public class productsservlet extends httpservlet {      @resource("jdbc/yourdb") // tomcat, define <resource> in context.xml , declare <resource-ref> in web.xml.     private datasource datasource;     private productdao productdao;      @override     public void init() {         productdao = new productdao(datasource);     }      @override     protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {         try {             list<product> products = productdao.list();             request.setattribute("products", products); // available ${products} in jsp             request.getrequestdispatcher("/web-inf/products.jsp").forward(request, response);         } catch (sqlexception e) {             throw new servletexception("cannot obtain products db", e);         }     }  }

  • finally jsp file in /web-inf/products.jsp uses jstl <c:foreach> iterate on list<product> made available in el ${products}, , uses jstl <c:out> escape string properties in order avoid xss holes when concerns user-controlled input.

    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <%@ taglib uri="http://java.sun.com/jsp/jstl/format" prefix="fmt" %> ... <table>     <c:foreach items="${products}" var="product">         <tr>             <td>${product.id}</td>             <td><c:out value="${product.name}" /></td>             <td><c:out value="${product.description}" /></td>             <td><fmt:formatnumber value="${product.price}" type="currency" currencycode="usd" /></td>         </tr>     </c:foreach> </table>

to work, call servlet url. provided servlet annotated @webservlet("/products") or mapped in web.xml <url-pattern>/products</url-pattern>, can call http://example.com/contextname/products

see also:


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