I wrote the following form and servlet , hoping that the servlet would return the value of the text field from the form , but it returns null instead. What should be corrected ?
<html>
<head>
<title>Simple form</title>
</head>
<body>
<form method="post" action="theServlet">
<input type="text" id="userName"/>
<input type="submit" value="Post"/>
</form>
</body>
</html>
public class theServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username=request.getParameter("userName");
response.setContentType("text/html");
PrintWriter writer=response.getWriter();
writer.println("<html>");
writer.println("userName = "+ username);
writer.println("</html>");
}
}
You should use name attribute instead of id to send parameters to the server.
<input type="text" id="userName" name="username" />
Related
I have the following situation:
There is my jsp file
<html>
<head>
<title>car.by</title>
</head>
<body>
<form method="get" action="${pageContext.request.contextPath}/editServlet">
<button type="submit">Редактировать(для админа)</button>
</form>
<form method="get" action="${pageContext.request.contextPath}/">
<button type="submit">Выйти</button>
</form>
<form method="get" action="${pageContext.request.contextPath}/">
<tr>
Марка <br>
Коробка передач <br>
Логин: <br>
<button type="submit">Показать</button> <br>
</tr>
</form>
<jsp:useBean id="cars" scope="request" type="java.util.List"/>
<c:forEach items="${cars}" var="car" varStatus="status">
<tr>
<img SRC=${car.c_photo} width="250" height="250"> <br>
Модель:<td>${car.c_model}</td><br>
Цена за день:<td>${car.c_price}</td><br>
Скидка:<td>${car.p_sale}</td><br>
Производитель:<td>${car.c_producer}</td><br>
Коробка передач:<td>${car.c_transmission}</td><br>
Место нахождения:<td>${car.c_owner}</td><br>
<form method="get" action="${pageContext.request.contextPath}/reservationServlet">
<button style="background-color: black" type="submit">Заказать</button>
</form>
</tr>
</c:forEach>
</body>
</html>
As you can see, here I have a list of forms. Each form has button. I don’t understand, how can I pass for example the car.c_model variable value from the jsp to servlet. Here is my servlet:
#WebServlet("/mainServlet")
public class MainServlet extends HttpServlet{
private CarManager carManager = new CarManager();
#Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
try {
List<Car> cars = carManager.getCarInfo();
req.setAttribute("cars", cars);
RequestDispatcher dispatcher = req.getRequestDispatcher("MainPage.jsp");
dispatcher.forward(req, resp);
} catch (SQLException e) {
e.printStackTrace();
}
}
#Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
}
}
I will appreciate any help, thanks in advance!
Hello, im working on a project in the university, and im stuck on an error.
Im working on a mypage feature, where you can update your old password, when you are looged in. The problem is that ChangepasswordServlet is not doing what it is supposed to do.
Here you can see my servlet, the problem is probably somewhere in the IF sentence. (Manager=Entitymanager)
#WebServlet(name = "ChangePasswordServlet", urlPatterns = {"/ChangePassword"})
public class ChangePasswordServlet extends HttpServlet {
#EJB
UserManagerLocal manager;
private void changePassword(HttpServletRequest request, HttpServletResponse response) throws IOException {
String loggedInUsersUsername = request.getRemoteUser();
/* PrintWriter writer = response.getWriter(); */
User userFromTheDB = manager.getUser(loggedInUsersUsername);
String oldPasswordFromDB = userFromTheDB.getPassword();
String oldPasswordFromForm = (String) request.getAttribute("theOldPW");
;
String newPasswordFromForm = (String) request.getAttribute("theNewPW");
String newPasswordToCheckFromForm = (String) request.getAttribute("theNewPWCheck");
try {
if (oldPasswordFromDB.toLowerCase().equals(oldPasswordFromForm.toLowerCase()) && newPasswordFromForm.toLowerCase().equals(newPasswordToCheckFromForm.toLowerCase())) {
userFromTheDB.setPassword(newPasswordFromForm);
manager.updateUser(userFromTheDB);
response.sendRedirect("/Slit/MyPage/PasswordSucsess.jsp");
} else {
response.sendRedirect("Slit/Error/error.jsp");
}
}
catch (NullPointerException en) {
PrintWriter print = response.getWriter();
print.println("nullpointeryes");
print.close();
}
}
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
changePassword(request, response);
}
#Override
protected void doPost (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
changePassword(request, response);
}
so
Here is my JSP with the form
<%# page contentType="text/html;charset=UTF-8" language="java" %>
<head>
<title>Her kan du endre ditt nåværende passord</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" type="text/css"
href="/Slit/Templates/CSS/MainPageTemplate.css">
</head>
<body>
<title>Slit</title>
<div>
<div class="form">
<form method="post" action="/Slit/ChangePassword">
<input type="Password" name="theOldPW" placeholder="Gammelt
Password"/>
<input type="Password" name ="theNewPW" placeholder="Nytt
Password"/>
<input type="Password" name ="theNewPWCheck" placeholder=" Nytt
Password på nytt"/>
<input type="submit" name="ByttePassord" value="Trykk her for å bytte
passord!"/>
</form>
</div>
</div>
</body>
</html>
</head>
<body>
</body>
So im getting nullpointer after i have filled in the form with the old and the new password.
If im running the code now, im getting the "nullpointeryes" error.
Edit:
This is the console error after filling in the form:
12:39:37,194 INFO [stdout] (default task-12) Hibernate: select
user0_.username as username2_3_0_, user0_.fName as fName3_3_0_, user0_.lName
as lName4_3_0_, user0_.password as password5_3_0_, user0_.DTYPE as
DTYPE1_3_0_ from User user0_ where user0_.username=?
Thanks for any answers
After hours i figured that i used get.attribute instead of parameter :/
String newPasswordFromForm = (String) request.getParameter("theNewPW");
String newPasswordToCheckFromForm = (String)
request.Paramter("theNewPWCheck");
This is my first time setting up a Java Servlet, I am trying to retrieve values into my Java Servlet from my input fields in my JSP Form when the user clicks a specific button. I also, am unsure if I used the proper practice for creating my Servlet. I simply right-clicked on my Apache Tomcat 8.0 server and then selected new Servlet.
Java Servlet:
#WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {
private static final long serialVersionUID = 3719628899527775749L;
public loginServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.getWriter().append("Served at: ").append(request.getContextPath());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
// do some processing here...
// get response writer
PrintWriter writer = response.getWriter();
// build HTML code
String htmlRespone = "<html>";
htmlRespone += "<h2>Your username is: " + username + "<br/>";
htmlRespone += "Your password is: " + password + "</h2>";
htmlRespone += "</html>";
// return response
writer.println(htmlRespone);
}
}
JSP:
<form name="loginForm" action="loginServlet" method="post" id="loginForm">
<div class="imgcontainer">
<img src="images/img_avatar2.png" alt="Avatar" class="avatar">
</div>
<div class="container">
<label><b>Username</b></label>
<input type="text" placeholder="Enter Username" name="uname" required>
<label><b>Password</b></label>
<input type="password" placeholder="Enter Password" name="psw" required>
<button id="loginButton" name="loginButton" type="submit">Login</button>
<button id="registerButton" name="registerButton" type="button">Register</button>
<input type="checkbox" checked="checked"> Remember me
</div>
<div class="container" style="background-color:#f1f1f1">
<button type="button" class="cancelbtn">Cancel</button>
<span class="psw">Forgot password?</span>
</div>
</form>
Your request attribute's name are uname and psw which are added on Jsp page. So you must change your doPost method like this.
String username = request.getParameter("uname");
String password = request.getParameter("psw");
Or
You must change your form in jsp page like this:
<label><b>Username</b></label>
<input type="text" placeholder="Enter Username" name="username" required>
<label><b>Password</b></label>
<input type="password" placeholder="Enter Password" name="password" required>
I have a very basic login servlet
#WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// get request parameters for userID and password
String username = request.getParameter("username");
String password = request.getParameter("password");
if (username.equals("marti") && password.equals("bosch")) {
response.sendRedirect("login_success.jsp");
} else {
RequestDispatcher rd = getServletContext().getRequestDispatcher(
"/login.html");
PrintWriter out = response.getWriter();
out.println("<font color=red>Either user name or password is wrong.</font>");
rd.include(request, response);
}
}
}
When I call the servlet it from the login.html:
<!DOCTYPE html>
<html>
<head>
<title>Login Page</title>
</head>
<body>
<form action="LoginServlet" method="post">
<p>Username: <input type="text" name="username"> </p>
<p>Password: <input type="password" name="password"> </p>
<p><input type="submit" value="Login"></p>
</form>
</body>
</html>
if I input the correct user name and password, the browser correctly renders login_success.jsp. However, when I do not enter the right user name and password, the browser shows the unrendered html as plain text:
<font color=red>Either user name or password is wrong.</font>
<!DOCTYPE html>
<html>
<head>
<title>Login Page</title>
</head>
<body>
<form action="LoginServlet" method="post">
<p>Username: <input type="text" name="username"> </p>
<p>Password: <input type="password" name="password"> </p>
<p><input type="submit" value="Login"></p>
</form>
</body>
</html>
How can I make the LoginServlet place the message under in the right place (after the body tag)? Thanks
Exactly, you need to put it as a content of an HTML document:
<!DOCTYPE html>
<html>
<head>
<title>Login Page</title>
</head>
<body>
<font color=red>Either user name or password is wrong.</font>
<form action="LoginServlet" method="post">
<p>Username: <input type="text" name="username"> </p>
<p>Password: <input type="password" name="password"> </p>
<p><input type="submit" value="Login"></p>
</form>
</body>
</html>
Additionally, a <font> tag is deprecated in HTML5.
EDIT:
So either you need to sendRedirect to the page where an error message is included:
response.sendRedirect("login_error.jsp"); //containing exactly the same html I posted
Or modify your form JSP, so it renders an additional error message after the authentication failure. You can accomplish that by passing a parameter from a Servlet to JSP. Refer to this thread.
This question already has answers here:
How perform validation and display error message in same form in JSP?
(3 answers)
Closed 3 years ago.
I have a JSP which will let a user register for an account at my website. If the user submits wrong or illegal info into the JSP, then I want to return the same JSP with an appropriate error message next to/above each wrongly filled (form) fields.
If possible, highlight the wrongly filled form field - this feature is not necessary though.
I have given a sample below to show what I need. I understand that the sample must be using something like javascript, but I don't know all that client side scripting. I only want to use JSP to do it. As I said, I want to sort of return the JSP form to the user after marking all the mistakes and how to correct them.
How do I do this ? I only need some initial direction. I will make the code myself and post it here later.
Thanks.
EDIT - I don't want the drop down box. I don't want red borders around wrongly entered fields. I only want to display the error messages (in red color) next to the relevant fields.
Here is some sample code -
<%# page language="java" contentType="blah..." pageEncoding="blah..."%>
<!DOCTYPE html PUBLIC "blah...">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
</head>
<body>
<form method="post" action = "/RegServlet">
user name: <input type="text" name="user"><br>
password : <input type="password" name="pwd">
</form>
</body>
</html>
RegServlet -
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class RegServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
static String okUser = "loser";
public RegServlet() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String user = request.getParameter("user");
String pwd = request.getParameter("pwd");
if(user.equalsIgnoreCase(okUser) == false){
//Do something MAGICAL to set an error next to username field of Form.jsp, then forward.
RequestDispatcher view = request.getRequestDispatcher("/jsp/Form.jsp");
view.forward(request, response);
}
}
}
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Ajax Validation</title>
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<!-- or download to a directory -->
<!-- <script src="js/jquery-1.9.1.js"></script> -->
<script type="text/javascript">
jQuery(document).ready(function(){
jQuery('#user').change(function() {
var userName = jQuery(this).val();
jQuery.ajax({
type : 'GET',
url : 'AjaxUserCheck',
data : {user:userName},
dataType : 'html',
success : function(data) {
if(jQuery.trim(data)=='1')
{
jQuery("#userLabel").html("Sorry! username is taken");
//write other stuff: border color ...
}
else if(jQuery.trim(data)=='0')
jQuery("#userLabel").html("user name available");
else
alert(data); //possible error
},
error : function(xhr,status,error){
console.log(xhr);
alert(status);
}
});
});
});
</script>
</head>
<body>
<form method="post" action = "/RegServlet">
user name: <input type="text" name="user" id="user">
<label id="userLabel"></label>
<br>
password : <input type="password" name="pwd">
</form>
</body>
</html>
---------Servlet------
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
String user = request.getParameter("user");
//if(dao.isUserExist(user)){
if(user.equals("java")){ // check for db if userid exists in DB print '1' else '0'
out.print("1");
}
else
out.print("0");
have the page post to itself, like this login.jsp fragment:
<div class="error">
<%
String usrName = "" + request.getParameter("username");
String usrPass = "" + request.getParameter("password");
if (isValid(usrName,usrPass){
openUserSession(usrName); //here you open a session and set the user, if the session doesn't have an user redirect to login.jsp
response.sendRedirect("index.jsp"); //user ok redirect to index (or previous page)
} else {
out.print("Invaid user or password");
}
%>
</div>
<form action="login.jsp" method="POST"> <!-- login.jsp post to itself -->
<input type="text" name="username" id="username"/>
<input type="password" name="password" />
<input type="submit" value="login" name="login" />
<input type="submit" value="register" name="register" />
</form>