Question

I am looking to know how to pass form values from an html from in a jsp page to a Java class when the JavaScript form validation returns true.

HTML code:

<form id="loginForm" onsubmit="return loginValidation()>
 <p class="error" id="liusrError"></p>
 <label for="usr">Username :</label>
 <br /> 
 <input type="text" name="liusr" id="liusr"> 
 <br />
 <p class="error" id="lipwdError"></p>
 <label for="pwd">Password :</label> <br /> 
 <input type="password" name="lipwd" id="lipwd">
 <br /> 
 <a id="fgtpwd" href="url">Forgot your password?</a> 
 <br /> 
 <input type="submit" value="Log In" id="logIn">
</form>

The JavaScript:

function loginValidation(){
 var pwd = document.getElementById("lipwd").value;
 var usr = document.getElementById("liusr").value;
 var error = false;

 if(pwd == null || pwd == ""){
  document.getElementById("lipwdError").innerHTML = "Please enter a valid password";
  error = true;
 }else{
  document.getElementById("lipwdError").innerHTML = " ";
 }

 if(usr == null || usr==""){
  document.getElementById("liusrError").innerHTML = "Please enter a valid username";
  error = true;
 }else{
  document.getElementById("liusrError").innerHTML = " ";
 }

 return error;
}

EDIT:

I want to know how to use this <% if ( request.getParameter("liusr") != null ) { %> to send the values entered in my form to my Java class only when the JavaScript function loginValidation returns true.

Answer 1

You probably want to have your <form> actually POST it’s contents to a URL when validation is complete:

<form id="loginForm" onsubmit="return loginValidation()" 
    method="POST" action="/login">

And then your Java class should be mapped to handle POST requests to /login.