Java Persistence (Books)

1.	Tạo web app BookCrud
2.0	Tạo bảng Books (BookID, Title, Price) trong DB Demo4 nếu chưa tạo
2.1	Mở admin console của Glassfish > Add Connection Pool
	+ Name: Demo4
	+ Type: javax.sql.DataSource
	+ Vendor: MicrosoftSqlServer
	+ Introspect: Enabled
	Next
	+ user: sa
	+ databaseName: Demo4
	+ password:
	+ serverName: localhost
	+ URL: jdbc:sqlserver://localhost:1433;databaseName=Demo4

2.2 Add Resource
	+ name: jdbc/demo
	+ chọn Pool vừa tạo

3.	Dừng Glassfish.
	Add > Other > Persistence > Entity Classes from Database > chọn dataSource mới tạo > chọn bảng Books > Next
	đặt trong package vn.aptech.entity rồi Finish

4. 	Tạo Servlet ControllerServlet trong vn.aptech.servlet
	Insert Code > Use Entity Manager
	Thêm đoạn sau ở cuối:

	public List<Books> getBooks(){
        List<Books> result = new ArrayList<>();
        try {
            utx.begin();
            Query q = em.createQuery("SELECT o FROM Books o");
            result = q.getResultList();
            utx.commit();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

	public Books getBook(int id) {
        Books b = new Books();
        try {
            utx.begin();
            b = em.find(Books.class, id);
            utx.commit();
        } catch (Exception e) {
            Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
            throw new RuntimeException(e);
        }
        return b;
    }

	public boolean create(Books b){
        try {
            utx.begin();
            em.persist(b);
            utx.commit();
        } catch (Exception e) {
            Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
            throw new RuntimeException(e);
        }
        return true;
    }

    public boolean update(Books b){
        try {
            utx.begin();
            em.merge(b);
            utx.commit();
        } catch (Exception e) {
            Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
            throw new RuntimeException(e);
        }
        return true;
    }

    public boolean delete(int id){
        try {
            utx.begin();
            em.remove(em.find(Books.class, id));
            utx.commit();
        } catch (Exception e) {
            Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
            throw new RuntimeException(e);
        }
        return true;
    }

5. New Standard Deployment Descriptor (web.xml), qua tab Pages, gõ ControllerServlet vào phần Welcome files

6. Thêm đoạn sau trong phần try ở method processRequest của ControllerServlet
	String action = request.getParameter("action");
	if (action == null) {
		request.setAttribute("books", getBooks());
		request.getRequestDispatcher("viewAll.jsp").forward(request, response);
	} else if (action.equals("add")) {
		response.sendRedirect("add.jsp");
	} else if (action.equals("addProcess")) {
		Books b = new Books();

		b.setBookID(Integer.parseInt(request.getParameter("BookID")));
		b.setTitle(request.getParameter("Title"));
		b.setPrice(Integer.parseInt(request.getParameter("Price")));

		create(b);
		response.sendRedirect("ControllerServlet");
	}  else if (action.equals("delete")) {
		String id = request.getParameter("BookID");
		delete(Integer.parseInt(id));
		response.sendRedirect("ControllerServlet");
	} else if (action.equals("update")) {
		String id = request.getParameter("BookID");
		Books b = getBook(Integer.parseInt(id));
		request.setAttribute("book", b);
		request.getRequestDispatcher("update.jsp").forward(request, response);
	} else if (action.equals("updateProcess")) {
		Books b = new Books();

		b.setBookID(Integer.parseInt(request.getParameter("BookID")));
		b.setTitle(request.getParameter("Title"));
		b.setPrice(Integer.parseInt(request.getParameter("Price")));

		update(b);
		HttpSession session = request.getSession();
		session.setAttribute("success", "Done.");
		response.sendRedirect("ControllerServlet?action=update&BookID="+b.getBookID());
	}

7. Tạo JSP: viewAll.jsp và đưa đoạn sau vào:
	<h1>Book Index</h1>
	<div><a href="ControllerServlet?action=add">Add new Book</a></div>
	<br/>
	<table border="1" style="margin-top: 5px">
		<thead>
			<tr>
				<th>ID</th>
				<th>Tittle</th>
				<th>Price</th>
				<th colspan="2">Action</th>
			</tr>
		</thead>
		<tbody>
		<%
			List<Books> list = (List<Books>)request.getAttribute("books");
			for (Books b : list) {
		%>
			<tr>
				<td><%= b.getBookID() %></td>
				<td><%= b.getTitle()%></td>
				<td><%= b.getPrice()%></td>
				<td><a href="ControllerServlet?action=update&BookID=<%=b.getBookID()%>">Update</a></td>
				<td><a href="ControllerServlet?action=delete&BookID=<%=b.getBookID()%>" onclick="return confirm('Are you sure to delete this?')">Delete</a></td>this?')">Delete</a></td>
			</tr>
		<%
			}
		%>
		</tbody>
	</table>

8. Tạo trang add.jsp và thêm đoạn sau
	<h1>Book - Add new</h1>
	<div><a href="ControllerServlet">Back to Index</a></div>
	<form action="ControllerServlet?action=addProcess" method="POST">
		<table>
			<tbody>
				<tr>
					<td>ID:</td>
					<td><input type="text" name="BookID"></td>
				</tr>
				<tr>
					<td>Title:</td>
					<td><input type="text" name="Title"></td>
				</tr>
				<tr>
					<td>Price:</td>
					<td><input type="number" name="Price"></td>
				</tr>
				<tr>
					<td></td>
					<td><input type="submit" name="btnAdd" value="Add this Book"></td>
				</tr>
			</tbody>
		</table>
	</form>

9. Tạo trang update.jsp và thêm đoạn sau
	<h1>Book - Update</h1>
	<p style="color:green">
		<%
			if (session.getAttribute("success") != null) {
				out.print(session.getAttribute("success"));
				session.removeAttribute("success");
			}
		%>
	</p>
	<div><a href="ControllerServlet">Back to Index</a></div>
	<form action="ControllerServlet?action=updateProcess" method="POST">
		<table >
			<tbody>
				<tr>
					<td>ID:</td>
					<td><input type="number" name="BookID" value="${book.bookID}" readonly="true" style="background-color: lightgray"></td>
				</tr>
				<tr>
					<td>Title:</td>
					<td><input type="text" name="Title" value="${book.title}"></td>
				</tr>
				<tr>
					<td>Price:</td>
					<td><input type="number" name="Price" value="${book.price}"></td>
				</tr>
				<tr>
					<td></td>
					<td><input type="submit" name="btnAdd" value="Update this Book"></td>
				</tr>
			</tbody>
		</table>
	</form>