We Keep Coding

How do I send data between two jsp?

I want to send the identificator of a product to the shoppingcard page and then display the product on the shoppingcart page
I used both request.set attribute and session.setattribute and it doesn't work. If I use session.getattribute or request.getattribute.toString() the page is white nothing is displayed. If I only use request.getAttribute (without toString) the line "ok" is not displayed on the result which means that purchased is null.
ProductStore is a map containing the products we have. Same for shoppingcardStore. ProductBean is the class of the products
products page:
<h2><%=ptp.getName()%></h2>
<div class="product-btns">
<form method="GET" action="<%="WhishList.jsp"%>">
<button class="main-btn icon-btn" name="id" value="<%=ptp.getId()%>"><i class="fa fa-heart"></i></button>
</form>
<button class="main-btn icon-btn"><i class="fa fa-exchange"></i></button>
<form action="shoppingcard.jsp" method="get">
<p> <%= ptp.getId() %> </p>
<%Object product=ptp;
request.setAttribute("purchase", ptp.getId());
%>
<input type="submit" value="add to cart">
<button class="primary-btn add-to-cart"><i class="fa fa-shopping-cart"></i> Add to Cart</button>
</form>
</div>
shoppingcard page
ProductStore products = new ProductStore();
Map<String,ProductBean> prodList = products.getProducts();
ShoppingcardStore db = new ShoppingcardStore();
Map<String,ProductBean> list = db.getShoppingcard();
Object purchased = request.getAttribute("purchase").toString();
if(purchased!=null){
out.println("<h1>Ok</h1>");
//ProductBean x = (ProductBean) purchased;
String x=(String) purchased;
db.Purchase(x);
//TODO confirm product has been added to the shoppingcart.
}%>
<!-- Product Slick -->
<div class="col-md-9 col-sm-6 col-xs-6">
<div class="row">
<div id="product-slick-1" class="product-slick">
<% if(list != null){
Object[] Shoppingcardlist = list.values().toArray();
ProductBean ptp;
for(int i = 0; i<Shoppingcardlist.length; i++){
ptp = (ProductBean)Shoppingcardlist[i];
// TODO display the info of the current wish list.
%>
of course it is just a part of my code, if you need to see something more tell me.

When you are doing setAttribute(), its scope is limited to the request when the main page is loading and hence will not be available on the next page as it will be a new request.
<%Object product=ptp;
request.setAttribute("purchase", ptp.getId());
%>
What you can do is, submit this value in URL param as GET or in a form (get/ post) to fetch it on next JSP using request.getParameter().
Or you can use session scope by session.setAttribute()
Hope it helps

Inserting into database from input by clicking a button

I have done the entire coding but data isnot getting inserted in the database
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection connection =
DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/userinfo?user=root&password=admin");
Statement statement = connection.createStatement() ;
resultset = statement.executeQuery("select * from item") ;
Now this is the part where i have done the connection and i think it is okay because in first part where i display values from database it is working
Now that i have done this in the next part i have taken input values from input boxes
<input type="submit" value="RECEIVE" style="width:100px; height:40px"
name="receive ">
now <%
PrintWriter pw = response.getWriter();
PreparedStatement pst = null;
if(request.getParameter("receive")!=null)
{
String dob=request.getParameter("datepicker");
String supplier=request.getParameter("supplier");
String type=request.getParameter("type");
String quantity=request.getParameter("quantity");
String queryString = "INSERT INTO stock_quantity values(?,?,?,?)";
pst = connection.prepareStatement(queryString);
pst.setString(2,dob);
pst.setString(3,supplier);
pst.setString(4,type);
pst.setString(5,quantity);
int i = pst.executeUpdate();
if(i!=0){
%>
<script language="javascript">
alert("Send sucess");
</script>
<%
}
else{
%>
<script language="javascript">
alert("Enter all data");
</script>
<%
}
}
%>
The data doesnt gets inserted.. Find the problem in the code

Don't make connection with db in first controller(in your case in jsp), just send your data to another controller, and there you can insert it to db. You can use either #Requestparam("param") to get single parameters, or #ModelAttribute("name") to get entire POJO object(where you will have your all parameteres).
So your html file would look like (in thymeleaf) you need to change some of thymeleaf things to jsp:
<form action="#" th:action="#{/save}" th:object="${yourObject}" method="post">
<div>
<label for="quantity">quantity:</label>
<input type="quantity" th:field="*{quantity}">
</div>
<button type="submit">Submit</button>
</form>
And your second controller:
#PostMapping("save")
public String reset(#ModelAttribute(value = "yourObject") YourPOJOClass request) {
//save to DB
}
If you want to accept parameters, not entire object, add name parameter to jsp/html
for example:
<div>
<label for="quantity">quantity:</label>
<input type="quantity" th:field="*{quantity}" name="quantity">
</div>
And in controller you can get this parameter like that:
#PostMapping("save")
public String reset(#RequestParam("quantity") String quantity)

Refreshing Page With A Parameter in JSP

I have a JSP page in my web application and i want to refresh the page with the parameter of option.
<select class="form-control combobox" name="education" >
<option value="" disabled selected hidden>Choose an education</option>
<option>English</option>
<option>French</option>
<option>Dutch</option>
<option>Spanish</option>
</select>
I want to use this parameter for querying my database again. Forexample;
<%
BookDAO bdao = new BookDAO();
for (TblBooks book : bdao.getAllBooks()) {%>
<tr>
<td><%=book.getTittle()%></td>
<td><%=boek.getAuthor()%></td>
<td><%=boek.getCategory()%></td>
<td><%=boek.getEducation()%></td>
<td><input type='checkbox' name ='chk1' /></td>
</tr>
<% }%>
I can get the parameter with request.getParameter("education") but how can i refresh page and query again with this parameter?

In Javascript, You can ask a web page to reload itself (the exact same URL) by:
location.href = location.href;
You can ask a web page to load a different location using the same mechanism:
location.href = 'http://www.google.com'; // or whatever destination url you want
You can get the value of a select control (which needs to have an id attribute):
var ctrl = document.getElementById("idOfSelectControl");
var selectedOption = ctrl.options[ctrl.selectedIndex].value;
So, if you update your JSP to give the control an id:
<select class="form-control combobox" id="education" name="education" >
you should be able to reload the page:
var educationControl = document.getElementById("education");
var selectedOption = educationControl.options[educationControl.selectedIndex].value;
location.href = "http://mysite.example/mypage?education=" + selectedOption;

By the help of Jason i have solved it. I added an onchange event to my select tag
onchange="changeThePage()"
Then i defined a javascript function.
function changeThePage() {
var selectedOption = "book.jsp?education=" + $("#education option:selected").text();
location.href = selectedOption;
}
Then i got the parameter by
String education = request.getParameter("education");
Then i added String education as parameter to my bdao.getAllBooks(education)) method for to query.

'
<script>
function abc(){
var yourSelect = document.getElementById( "ddlViewBy" );
var val = yourSelect.options[ yourSelect.selectedIndex ].value;
//window.location.href=window.location.href;
alert(val);
window.location.replace("index.jsp?name="+val);
}
</script>
<select id="ddlViewBy" onchange="abc()">
<option>select</option>
<option value="1">test1</option>
<option value="2">test2</option>
<option value="3">test3</option>
</select>
<%
String name=request.getParameter("name");
if(name!=null){
%>
<table>
<tr>
<td>author<%=name%></td>
<td>book name<%=name%></td>
</tr>
</table>
<%
}
%>
Hi,
try this, this will be helpful,
when you select a value it will call abc, function and then you are assigning that value in scriptlet..and also page is refreshing. in scriptlet you can access that value using request.getParameter("name").
now you can write your code inside scriptlet..hope helpful for someone.. :)
thanks...

Creating Multiple textboxes dynamically

I am making a web application in which I pass a Int value from a servlet to next jsp page like this :
request.setAttribute("n",n);
RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/sharingfilesselection.jsp");
dispatcher.forward(request, response);
Now on the next page i.e sharingfilesselection.jsp I want that n textboxes are created dynamically each with a different id as i need to store the values of these textboxes in my database.
The N is obtained on next jsp page by this :
Object N=request.getAttribute("n");
How this can be done using javascript ?Please help

You can do this using JSTL:
<c:forEach var="i" begin="1" end="${n}">
Input ${i}: <input type="text" name="txtDynamic_${i}" id="txtDynamic_${i}" />
<br />
</c:forEach>

Try this in your
.javascript
<%String n=(String)request.getAttribute("n");%>
var n=<%=n%>;
for(var i=0;i<n;i++{
$(".exac").append("<input type="text" id='textbox"+i+"'></input>");
}
}
.html
<div class="exac">
</div>

Working sample here
html
<div id="container"><input type="button" onclick="createTextBox(5)" value="create textbox">
JS
function createTextBox(n) {
for (var i = 0; i < n; i++) {
var textBox = document.createElement("input");
textBox.setAttribute("id", "text_" + i);
document.getElementById("container").appendChild(textBox);
}}

Dynamically display multiple images from database to jsp?

Hello fellow stack overflowers.
I am stuck on a certain portion of a project and am looking for some advice.
I have a photo gallery page in jsp that is set up to display all the listings of photo albums and the photos within them based on the user's interest. It is currently set up so that whatever 'photo' option is selected will be redirected to another jsp with the outputstream decoding on that particular page. However, in order to see another photo or image, the user has to go 'back' to the photo galleries page and select another image for a new photo.
Is there a way to set up the galleries page so that all the photos can be dynamically displayed on the page OR is there possibly a way put some direction on the display.jsp page so that the user can simply click from one photo to the next?????
Code is below.
<div id="subSlideshow">
<table>
<tr>
<td id="subpageSlideshow">
<table>
<tr>
<td>
<h1 id="subpageTitle">Galleries</h1>
<form action="gallery" method="get">
<%try{
Connection conn = GalleriesConnection.connect();
Statement st = conn.createStatement();
String sql = "SHOW TABLES IN GALLERIES;";
ResultSet rs = st.executeQuery(sql);
while(rs.next()){%>
<input class="wineDiv" type="submit" name="gallery" value="<%=rs.getString(1).toLowerCase() %>" />
<%}
rs.close();
st.close();
GalleriesConnection.close(conn);
}
catch(Exception e){
}%>
</form>
<td>
</tr>
<tr>
<td>
<h1 id="subpageTitle">Images</h1>
<form action="pictures/display.jsp">
<%try{
Connection conn = GalleriesConnection.connect();
Statement st = conn.createStatement();
String sql = "SELECT PHOTO_NAME FROM "+gallery+" ;";
ResultSet rs = st.executeQuery(sql);
while(rs.next()){
String photoName = rs.getString(1);
%>
<input class="wineDiv" type="submit" name="photo" value="<%=photoName %>" />
<% }
rs.close();
st.close();
GalleriesConnection.close(conn);
} catch(Exception e){
}%>
</form>
</td>
</tr>
</table>
</td>
<td id="subpageInfo">
<h1 id="subpageTitle">Click on an image to see a larger view</h1>
<div id="slider">
<script src ="js/slides.js" type="text/javascript"></script>
<img id="1" src="pictures/winery_image1.jpg" />
<img id="2" src="pictures/winery_image2.jpg" />
<img id="3" src="pictures/winery_image3.jpg" />
<img id="4" src="pictures/winery_image4.jpg" />
<img id="5" src="pictures/winery_image5.jpg" />
</div>
<input class="previous" onclick="prev(); return false;" value="Previous Image" />
<input class="next" onclick="next(); return false;" value="Next Image" />
</td>
</tr>
</table>
</div>
All the action on the page is within this div. The first connection command retrieves all the table names in the database and spits the table names out on submit buttons. Additionally, the images currently listed in the subpageInfo are one of the desired spots on where I would like images from the database to be embedded. They make a nice little fadeOut() fadeIn() transition when the next and previous buttons are selected.
The second connection gets all the names of the photos and puts them in the form of submits as well. Selected photo names are sent to this page:
<%# page import="java.sql.*"%>
<%# page import="java.io.*"%>
<%
byte[] imgData = null;
%>
<jsp:scriptlet>
String photo = request.getParameter("photo");
</jsp:scriptlet>
<%
try {
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:8889/GALLERIES","myusername","mypassword");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("SELECT PHOTO FROM PHOTOS WHERE PHOTO_NAME = '"+photo+"';");
while (rs.next()) {
Blob image = rs.getBlob(1);
imgData = image.getBytes(1,(int)image.length());
}
// display the image
response.setContentType("image/png");
OutputStream o = response.getOutputStream();
o.write(imgData);
o.flush();
o.close();
rs.close();
stmt.close();
con.close();
} catch (Exception e) {
out.println("Unable To Display image");
out.println("Image Display Error=" + e.getMessage());
return;
}
%>
This program does everything it is asked to do, but I am having some difficulty on making it more user friendly. The desired effect is either embed the images in the subpageInfo div or to have some directives on the display.jsp page to go from one image to the next.
As always any and all help is greatly appreciated.

If you want to present a set of pictures I'd go for:
http://lokeshdhakar.com/projects/lightbox2/
Or if you want to do everything yourself, use only one page - use the selection form you mentioned and after sumbition, reload the same page including a decoded image into it. You can setup a javascript so that everytime user selects another picture the form gets submited so user doesn't have to click submit.
But I suggest rethinking the whole thing. What's your goal? Is this approach the best one? I'm usually way too deep in technical stuff that I don't see the solution user expects. That's why I ask random people to help me out.
Also - scriptlets? ew! Use JSTL and prepare everything in the controller. Or use Primefaces, JSF, managed beans and all the stuff that was made for this purpose.