I would like to write an article for those who are writing applications for the first time using Java. We would appreciate it if you could use it as a reference for creating training assignments for your portfolio and company. This time, we will create a task manager. By applying this, you can also use it to create Twitter clones.
I will post articles for each function of the application.
eclipse4.16.0 Tomcat9 Java11
Create a search form and task list table
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.util.List, model.entity.TaskBean, model.entity.UserBean, model.dao.UserDAO, model.dao.CategoryDAO, model.dao.StatusDAO"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Task list</title>
<link rel="stylesheet" href="${pageContext.request.contextPath}/task-list.css">
</head>
<body>
<%
List<TaskBean> tasklist = (List<TaskBean>) request.getAttribute("tasklist");
UserDAO userdao = new UserDAO();
CategoryDAO categorydao = new CategoryDAO();
StatusDAO statusdao = new StatusDAO();
String error = (String)request.getAttribute("error");
%>
<!-- *****************Search form**********************-->
<jsp:include page="header.jsp"/>
<div class="contain">
<h3>Squeeze search</h3>
<form action="task-search-servlet" method="post">
<table class="form-table search-table">
<tbody>
<tr>
<th>Narrow down by task name</th>
<td>
<div class="search-key">
<input type="text" class="form-control" name="task_name">
</div>
</td>
</tr>
<tr>
<th>Narrow down by category</th>
<td>
<div class="search-key">
<select class="form-control" name="category_id">
<option selected>Choose...</option>
<option value="1">New product A: Development project</option>
<option value="2">Existing product B:Improvement project</option>
</select>
</div>
</td>
</tr>
<tr>
<th>Narrow down by status</th>
<td>
<div class="search-key">
<select class="form-control" name="status_code">
<option selected>Choose...</option>
<option value="00">not started yet</option>
<option value="50">Start</option>
<option value="99">Done</option>
</select>
</div>
</td>
</tr>
<tr>
<th><input type="submit" value="Search" class="search-button"></th>
<td>
</td>
</tr>
</tbody>
</table>
</form>
<!-- *****************Task list table (sort with ▼ button without table)*********-->
<h3>Task list</h3>
<%if(error != null){ %>
<p class="error"><%=error %></p>
<%} %>
<div class="table-wrapper">
<table class="list-table" border="1">
<thead>
<tr class="table-header">
<th class="fixed01">
<div class="title">Task ID</div>
<div class="sort-box" >
<form action="task-list-servlet" method="post" class="sort-form">
<input type="submit" value="▲" class="sort">
</form>
<form action="task-order-by-id-desc" method="post" class="sort-form">
<input type="submit" value="▼" class="sort">
</form>
</div>
</th>
<th class="fixed01"><div class="title">Task name</div></th>
<th class="fixed01">
<div class="title">Category</div>
<form action="task-order-by-category-servlet" method="post" class="sort-form">
<input type="submit" value="▲" class="sort">
</form>
<form action="task-order-by-category-desc" method="post" class="sort-form">
<input type="submit" value="▼" class="sort">
</form>
</th>
<th class="fixed01">
<div class="title">Deadline</div>
<form action="task-order-by-limit-servlet" method="post" class="sort-form">
<input type="submit" value="▲" class="sort">
</form>
<form action="task-order-by-limit-desc" method="post" class="sort-form">
<input type="submit" value="▼" class="sort">
</form>
</th>
<th class="fixed01">
<div class="title">User</div>
<form action="task-order-by-user-servlet" method="post" class="sort-form">
<input type="submit" value="▲" class="sort">
</form>
<form action="task-order-by-user-desc" method="post" class="sort-form">
<input type="submit" value="▼" class="sort">
</form>
</th>
<th class="fixed01">
<div class="title">status</div>
<form action="task-order-by-status-servlet" method="post" class="sort-form">
<input type="submit" value="▲" class="sort">
</form>
<form action="task-order-by-status-desc" method="post" class="sort-form">
<input type="submit" value="▼" class="sort">
</form>
</th>
<th class="title fixed01">Note</th>
<th class="title fixed01">Registered Date</th>
<th class="title fixed01">Update date and time</th>
<th colspan="3" class="title fixed01">Task management</th>
</tr>
</thead>
<tbody>
<%
for(TaskBean task : tasklist){
String user_name = userdao.getUserName(task.getUser_id());
String category_name = categorydao.getCategoryName(task.getCategory_id());
String status_name = statusdao.getStatusName(task.getStatus_code());
%>
<tr >
<td class="parameter"><%=task.getTask_id() %></td>
<td class="parameter"><%=task.getTask_name() %></td>
<td class="parameter"><%=task.getCategory_id() %>：<%=category_name %></td>
<td class="parameter"><%=task.getLimit_date() %></td>
<td class="parameter"><%=user_name %></td>
<td class="parameter"><%=task.getStatus_code() %>：<%=status_name %></td>
<td class="parameter"><%=task.getMemo() %></td>
<td class="parameter"><%=task.getCreate_datetime() %></td>
<td class="parameter"><%=task.getUpdate_datetime() %></td>
<td class="parameter">
<form action="task-update-detail-servlet" method="post">
<input type="hidden" name="task_id" value="<%=task.getTask_id() %>">
<button type="submit" class="task-button">update</button>
</form>
</td>
<td class="parameter">
<form action="task-delete-detail-servlet" method="post">
<input type="hidden" name="task_id" value="<%=task.getTask_id() %>">
<button type="submit" class="task-button">Delete</button>
</form>
</td>
<td class="parameter">
<form action="comment-detail-servlet" method="post">
<input type="hidden" name="task_id" value="<%=task.getTask_id() %>">
<button type="submit" class="task-button">comment</button>
</form>
</td>
</tr>
<%
}
%>
</tbody>
</table>
</div>
</div>
</body>
</html>
You can easily create a SQL statement for sorting by changing the t_task part of this SQL statement to category_id or limit_date. This time, we made it possible to sort in the order of task_id, limit_date, category_id, status_code, user_id.
model.dao.TaskDAO.java
/**
*List of tasks
* @return tasklist
* @throws SQLException
* @throws ClassNotFoundException
*/
//By task ID
public List<TaskBean> getTaskList() throws SQLException, ClassNotFoundException{
String sql = "select * from t_task";
List<TaskBean> tasklist = new ArrayList<TaskBean>();
try(Connection con = ConnectionManager.getConnection();
Statement stmt = con.createStatement();
ResultSet res = stmt.executeQuery(sql)){
//The acquired SQL columns are stored in the task object in order. Finally add to tasklist
while(res.next()) {
TaskBean task = new TaskBean();
task.setTask_id(res.getInt("task_id"));
task.setTask_name(res.getString("task_name"));
task.setCategory_id(res.getInt("category_id"));
task.setLimit_date(res.getDate("limit_date"));
task.setUser_id(res.getString("user_id"));
task.setStatus_code(res.getString("status_code"));
task.setMemo(res.getString("memo"));
task.setCreate_datetime(res.getTimestamp("create_datetime"));
task.setUpdate_datetime(res.getTimestamp("update_datetime"));
tasklist.add(task);
}
}
return tasklist;
}
//Reverse
public List<TaskBean> getTaskListOrderByIdDesc() throws SQLException, ClassNotFoundException{
String sql = "select * from t_task order by task_id desc";
List<TaskBean> tasklist = new ArrayList<TaskBean>();
try(Connection con = ConnectionManager.getConnection();
Statement stmt = con.createStatement();
ResultSet res = stmt.executeQuery(sql)){
//The acquired SQL columns are stored in the task object in order. Finally add to tasklist
while(res.next()) {
TaskBean task = new TaskBean();
task.setTask_id(res.getInt("task_id"));
task.setTask_name(res.getString("task_name"));
task.setCategory_id(res.getInt("category_id"));
task.setLimit_date(res.getDate("limit_date"));
task.setUser_id(res.getString("user_id"));
task.setStatus_code(res.getString("status_code"));
task.setMemo(res.getString("memo"));
task.setCreate_datetime(res.getTimestamp("create_datetime"));
task.setUpdate_datetime(res.getTimestamp("update_datetime"));
tasklist.add(task);
}
}
return tasklist;
}
First, it is displayed when transitioning from the menu screen. If you are not logged in, the list will not be displayed.
servlet.TaskListServlet.java
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
TaskDAO dao = new TaskDAO();
try {
HttpSession session = request.getSession();
boolean logincheck = (Boolean)session.getAttribute("login");
if(logincheck) {
//Save all acquired tasks to request scope
List<TaskBean> tasklist = dao.getTaskList();
request.setAttribute("tasklist", tasklist);
//Forward
RequestDispatcher rd = request.getRequestDispatcher("task-list.jsp");
rd.forward(request, response);
}
} catch(SQLException | ClassNotFoundException | NullPointerException e) {
e.printStackTrace();
RequestDispatcher rd = request.getRequestDispatcher("login.html");
rd.forward(request, response);
}
The following is an example of a Servlet sent when each sort button is pressed. Create a Servlet for each sorting method defined in TaskDAO.java. For example, this is a Servlet that gets tasks in descending order of task_id.
TaskOrderByIdDesc.java
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
TaskDAO dao = new TaskDAO();
List<TaskBean> tasklist = null;
try {
//Just change the method used here.
tasklist = dao.getTaskListOrderByIdDesc();
} catch(SQLException | ClassNotFoundException e) {
e.printStackTrace();
}
request.setAttribute("tasklist", tasklist);
RequestDispatcher rd = request.getRequestDispatcher("task-list.jsp");
rd.forward(request, response);
}
This completes the task list display and sort function.
Next, we will implement the search function.
The search function will be able to narrow down by task_name, category_id, status_code.
/**
*Search method
* @param task_name
* @param category_id
* @param status_code
* @return
* @throws SQLException
* @throws ClassNotFoundException
*/
public List<TaskBean> searchTask(String task_name, int category_id, String status_code) throws SQLException, ClassNotFoundException{
//SQL statement (used when all search forms are filled)
String sql = "select * from t_task where task_name like ? and category_id = ? and status_code = ?";
//Create a SQL statement that uses only the selected items for each search item
if(category_id == 0 && status_code == "0") {
sql = "select * from t_task where task_name like ?";
}else if(category_id ==0) {
sql = "select * from t_task where task_name like ? and status_code = ?";
}else if(status_code == "0") {
sql = "select * from t_task where task_name like ? and category_id = ?";
}
List<TaskBean> tasklist = new ArrayList<TaskBean>();
try(Connection con = ConnectionManager.getConnection();
PreparedStatement pstmt = con.prepareStatement(sql)){
//As before, for each search item, assign and specify arguments in a form that matches the SQL statement that uses only the selected ones.
if(category_id == 0 && status_code == "0") {
pstmt.setString(1, task_name);
}else if(category_id ==0) {
pstmt.setString(1, task_name);
pstmt.setString(2, status_code);
}else if(status_code == "0") {
pstmt.setString(1, task_name);
pstmt.setInt(2, category_id);
}else {
pstmt.setString(1, task_name);
pstmt.setInt(2, category_id);
pstmt.setString(3, status_code);
}
ResultSet res = pstmt.executeQuery();
//The acquired SQL columns are stored in the task object in order. Finally add to tasklist
while(res.next()) {
TaskBean task = new TaskBean();
task.setTask_id(res.getInt("task_id"));
task.setTask_name(res.getString("task_name"));
task.setCategory_id(res.getInt("category_id"));
task.setLimit_date(res.getDate("limit_date"));
task.setUser_id(res.getString("user_id"));
task.setStatus_code(res.getString("status_code"));
task.setMemo(res.getString("memo"));
task.setCreate_datetime(res.getTimestamp("create_datetime"));
task.setUpdate_datetime(res.getTimestamp("update_datetime"));
tasklist.add(task);
}
}
return tasklist;
}
Please try while looking at the comments.
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
TaskDAO taskdao = new TaskDAO();
List<TaskBean> tasklist = new ArrayList<TaskBean>();
//Get request parameters
request.setCharacterEncoding("UTF-8");
String task_name = request.getParameter("task_name");
String category_id_str = request.getParameter("category_id");
String status_code = request.getParameter("status_code");
//Check for input omissions
if(category_id_str.equals("Choose...")) {
category_id_str = "0";
}
if(status_code.equals("Choose...")) {
status_code = "0";
}
task_name = "%" + task_name + "%";
//category_Return id to int type
int category_id = Integer.parseInt(category_id_str);
try {
//Search by refined content
tasklist = taskdao.searchTask(task_name, category_id, status_code);
//If there are 0 tasklists, an error screen will be displayed.
if(tasklist.size() == 0) {
String error = "There is no result";
request.setAttribute("error", error);
}
}catch(SQLException | ClassNotFoundException e) {
e.printStackTrace();
RequestDispatcher rd = request.getRequestDispatcher("task-list-servlet");
rd.forward(request, response);
}
request.setAttribute("tasklist", tasklist);
RequestDispatcher rd = request.getRequestDispatcher("task-list.jsp");
rd.forward(request, response);
}
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