javakrishna: How to create dynamic drop down list in JSP from database

https://www.codejava.net/java-ee/jsp/how-to-create-dynamic-drop-down-list-in-jsp-from-database

Database:

Create table category(category_id int auto_increment, name varchar(50), primary key (id))

Model

***************************************************************************************

package net.codejava;

public class Category {

private int id;

private String name;

public Category(int id, String name) {

super();

this.id = id;

this.name = name;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

DAO

***************************************************************************************

package net.codejava;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.List;

public class CategoryDAO {

String databaseURL = "jdbc:mysql://localhost:3306/bookstoredb";

String user = "root";

String password = "pass";

public List<Category> list() throws SQLException {

List<Category> listCategory = new ArrayList<>();

try (Connection connection = DriverManager.getConnection(databaseURL, user, password)) {

String sql = "SELECT * FROM category ORDER BY name";

Statement statement = connection.createStatement();

ResultSet result = statement.executeQuery(sql);

while (result.next()) {

int id = result.getInt("category_id");

String name = result.getString("name");

Category category = new Category(id, name);

listCategory.add(category);

}

} catch (SQLException ex) {

ex.printStackTrace();

throw ex;

}

return listCategory;

}

Controller:

***************************************************************************************

package net.codejava;

import java.io.IOException;

import java.sql.SQLException;

import java.util.List;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/list")

public class ListServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

CategoryDAO dao = new CategoryDAO();

try {

List<Category> listCatagory = dao.list();

request.setAttribute("listCategory", listCatagory);

RequestDispatcher dispatcher = request.getRequestDispatcher("index.jsp");

dispatcher.forward(request, response);

} catch (SQLException e) {

e.printStackTrace();

throw new ServletException(e);

}

***************************************************************************************

package net.codejava;

import java.io.IOException;

import java.sql.SQLException;

import java.util.List;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/list")

public class ListServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

listCategory(request, response);

}

private void listCategory(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

CategoryDAO dao = new CategoryDAO();

try {

List<Category> listCatagory = dao.list();

request.setAttribute("listCategory", listCatagory);

RequestDispatcher dispatcher = request.getRequestDispatcher("index.jsp");

dispatcher.forward(request, response);

} catch (SQLException e) {

e.printStackTrace();

throw new ServletException(e);

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

int categoryId = Integer.parseInt(request.getParameter("category"));

request.setAttribute("selectedCatId", categoryId);

listCategory(request, response);

}

Views:

***************************************************************************************

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<html>

<head>

<title>Dynamic Drop Down List Demo - CodeJava.net</title>

</head>

<body>

<h2>Dynamic Drop Down List Demo</h2>

Select a Category: 

<c:forEach items="${listCategory}" var="category">

<option value="${category.id}"

<c:if test="${category.id eq selectedCatId}">selected="selected"</c:if>

${category.name}

</option>

</c:forEach>

</select>

</form>

</div>

</body>

</html>

Ajax Implementation:

***************************************************************************************

package net.codejava;

import java.io.IOException;

import java.sql.SQLException;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.google.gson.Gson;

@WebServlet("/listajax")

public class ListAjaxServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

CategoryDAO dao = new CategoryDAO();

try {

List<Category> listCatagory = dao.list();

String json = new Gson().toJson(listCatagory);

response.setContentType("application/json");

response.setCharacterEncoding("UTF-8");

response.getWriter().write(json);

} catch (SQLException e) {

e.printStackTrace();

throw new ServletException(e);

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

String category = request.getParameter("category");

String text = "Server replies: You selected category: " + category;

response.setContentType("text/plain");

response.setCharacterEncoding("UTF-8");

response.getWriter().write(text);

}

***************************************************************************************

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<html>

<head>

<title>Dynamic Drop Down List Demo (AJAX) - CodeJava.net</title>

$(document).on("click", "#buttonLoad", function() {

$.get("listajax", function(responseJson) {

var $select = $("#dropdownlist");

$select.find("option").remove();

$.each(responseJson, function(index, category) {

$("<option>").val(category.id).text(category.name).appendTo($select);

});

$(document).on("click", "#buttonSubmit", function() {

var params = {category : $("#dropdownlist option:selected").text()};

$.post("listajax", $.param(params), function(responseText) {

alert(responseText);

});

</script>

</head>

<body>

<h2>Dynamic Drop Down List (AJAX) Demo</h2>

<button id="buttonSubmit">Submit</button>

</div>

</body>

</html>

javakrishna

How to create dynamic drop down list in JSP from database

No comments:

Post a Comment