I am trying to send login data in JSON format to a servlet using AJAX, but for some reason the servlet is getting null values. My servlet works fine when I send the data without AJAX, but when I use it it seems that my script is not getting any values.
Login form:
<form>
<input type="text" placeholder="Enter Email"
name="email" required><br>
<input type="password" placeholder="Enter Password"
name="paswd" required><br>
<input type="button" value="Log in"
onclick="loginAjax(this.form)">
</form>
AJAX:
function loginAjax(form) {
var user = new Object();
user.email = form.email.value;
user.paswd = form.paswd.value;
var jsonUser = JSON.stringify(user);
console.log(user.email);
console.log(user.paswd);
console.log(jsonUser);
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("result").innerHTML = this.responseText;
//Empty form fields
form.email.value = "";
form.paswd.value = "";
}
};
xmlhttp.open("POST", "./login", true);
xmlhttp.setRequestHeader("Content-type", "application/json");
xmlhttp.send(jsonUser);
}
Servlet:
@ WebServlet(name = "login", urlPatterns = { "/login" })
public class Login extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.sendRedirect("index.html");
}
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType(MediaType.APPLICATION_JSON);
response.setCharacterEncoding("UTF-8");
Dao dao = new Dao();
// return values as string.
String email = request.getParameter("email");
String password = request.getParameter("paswd");
System.out.println("Your email: " email );// Delete Later!!
System.out.println("Your password: " password);// Delete Later!!
System.out.println("Test passed0");
// Read reference values from DB
String salt = dao.getUserSalt(email);
String hashpw = dao.getUserpasswordHash(email);
System.out.println("Test 1 passed");
dao.checkemail(email);
try {
System.out.println("Test 2 passed");
if (SecurityUtils.isPasswordOk(hashpw, password, salt)) {
System.out.println("Test 3 passed");
String data = email;
HttpSession session = request.getSession();
User user = dao.readUserInfo(data);
dao.close();
System.out.println("Test 4 passed");
session.setAttribute("LoggedUser", user);
System.out.println("Session: " request.getSession(false));
session.setMaxInactiveInterval(30 * 60);
System.out.println("Test 5 passed");
String encodedURL = response.encodeRedirectURL("/userInfo?email=" data);
System.out.println("Final Test 6 passed");
try {
response.sendRedirect(encodedURL);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
dao.close();
RequestDispatcher rd = getServletContext().getRequestDispatcher("./index.html");
try {
rd.include(request, response);
} catch (ServletException | IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
The output I get on the console:
Your email: null
Your password: null
java.lang.NullPointerException
at security.SecurityUtils.getPasswordHashed(SecurityUtils.java:32)
at security.SecurityUtils.isPasswordOk(SecurityUtils.java:57)
at app.Login.doPost(Login.java:54)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:526)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:593)
at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1459)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799)
at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1631)
at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:148)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at ..Error continues...
I tried to switch the input type to submit and then added return false next to the onclick as the following onclick="loginAjax(this.form); return false" but that didn't help. I previously used similar ajax function with a form to send data to PHP and it worked fine. Any help would be much appreciated!
CodePudding user response：
From the Documentation of XMLHttpRequest
XMLHttpRequest send() accepts an optional parameter which lets you specify the request's body; this is primarily used for requests such as PUT. If the request method is GET or HEAD, the body parameter is ignored and the request body is set to null.
Apparently you are sending JSON data into your request body whereas you are expecting your data in request Parameter
String email = request.getParameter("email");
String password = request.getParameter("paswd");
Certainly it will return NULL
In this case you need to read request body from request.getInputStream()
Check this answer
CodePudding user response：
try
xmlhttp.open("POST","./login?email=" user.email "&paswd=" user.paswd,false);
xmlhttp.send();
instead of
xmlhttp.open('POST', './login', false);
xmlhttp.send(jsonUser);
OR YOU CAN USE JQUERY AJAX
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js"></script>
<script>
function loginAjax(form) {
var user = new Object();
user.email = form.email.value;
user.paswd = form.paswd.value;
var jsonUser = JSON.stringify(user);
$.ajax({type: "POST",
url:"./login",
data:jsonUser,
success:function(result){
alert("Success");
}
});
}
</script>