Passing web browser client input to server Java source code

I am developing a web application in Java that takes a string containing a website URL, parses the website HTML to gather information, then uses that information to query a postgresql database. This is already written using Java, HTML, JS and CSS.

In my HTML I have a text input box where the user can paste a URL and submit it using a button. What I would like to do, is get this URL as the String I mentioned above in my Java code, versus hard coding it myself. Eventually, after parsing that URL HTML file and running whatever queries I need on my database, I will return the query results back to the browser for the user to see.

I understand that JavaScript runs in the browser while my Java source code is server side at different times. I've gathered that a possible solution is to submit a HTTPServletRequest in my Java source code that communicates with my JavaScript; however I am unsure of the right steps to accomplish this. XmlHTTPRequest is something else I've seen being used.

Edit - After further reading I am deciding between programming a Java servlet, or a JSP to handle this. I am leaning towards a servlet as I am more familiar with Java than HTML, and will be using more logic (HTML parsing, RDBMS querying using jdbc, returning data).

Does this seem to be the correct decision?

I hope I worded this clearly and that this is a valid question! Thank you!

UPDATE/EDIT

Here is my code I've done so far after thinking about Mois44's answer. I am unsure what to put for the URL in my xmlHttp.send() request. In the browser, there is a text box, and submit button for the user as I said.

Error: url.html:91 POST http://localhost:8080/myapplication/GetURL?url=http://mywebsite.com/category/123986/webpage/ 404 (Not Found)

This is the project structure for these files:

src/main/
|
|----java/
|   |
|   |----path/to/java/servlet/myServlet.java
|
|----webapp/
    |
    |----META-INF/
    |   |----web.xml
    |
    |----pages/
        |----url.html
    |
    index.html

web.xml:

<servlet>
   <servlet-name>GetURL</servlet-name>
   <servlet-class>path.to.java.servlet.myServlet</servlet-class>

   <init-param>
    <param-name>url</param-name>
    <param-value>www.testurl.com</param-value>  // don't I set this in my url.html from user?
  </init-param>

</servlet>

<servlet-mapping>
  <servlet-name>myServlet</servlet-name>
  <url-pattern>/myServlet/*</url-pattern> // not sure about this...
</servlet-mapping>

url.html:

<div class="url-input">
    <input type="text" id="txtUrl" class="text-box" value="Paste recipe website URL here" align="middle">
    <button onclick="urlRequest()" id="myid" value="myvalue">Go!</button>
        <script>
            function getURL(xmlHttp) {
                document.getElementById("myid").value = xmlHttp.responseText;
                return document.getElementById("txtUrl").value
            }
        </script>
        <script>
            function urlRequest() {
                var xmlHttp = new XMLHttpRequest();
                var url = getURL(xmlHttp);
                xmlHttp.open('POST', 'http://localhost:8080/myapplication/GetURL?url='+url, true);

                xmlHttp.onreadystatechange = function () {
                    if (xmlHttp.readyState = 4 && xmlHttp.status == 200) {
                        alert(xmlHttp.responseText);
                    }
                };
                xmlHttp.send(url);
            }
        </script>
</div>

myServlet.java:

public class Servlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    handleRequest(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        handleRequest(request, response);
    }

    protected void handleRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

        String p = request.getParameter("url");
        System.out.println("test");
        System.out.println(p);
    }
}