function applyFilter(){
        idFilterJS = getRadioValue();
        var url = "applyfilter?action=applyfilterXML&id=" + idFilterJS;
        req = initRequest();
        req.open("GET", url, true);
        req.onreadystatechange = applyFilterCallBack;
        req.send(null);
    }

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        session = request.getSession();
        String action = request.getParameter("action");
}

var idFilterJS;
var isIE;
var eventsTable;
var req;

function applyFilter(){
    idFilterJS = getRadioValue();
    var url = "http://applyfilter?action=applyfilterXML&id=" + idFilterJS;
    req = initRequest();
    req.open("GET", url, true);
    req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    req.onreadystatechange = applyFilterCallBack;
    req.send(null);
}

function getRadioValue() {
    var inputs = document.getElementsByName("filter");
    for (var i = 0; i < inputs.length; i++) {
        if (inputs[i].checked) {
            return inputs[i].value
        }
    }
}

function initRequest(){
    if (window.XMLHttpRequest) {
        if (navigator.userAgent.indexOf('MSIE') != -1){
            isIE = true;
        }
        return new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        isIE = true;
        return new ActiveXObject("Microsoft.XMLHTTP");
    }
}

<div id="filters-list">
        <form name="applyfilter" action="applyfilter">
            <fieldset>
                <legend>Filters</legend>
                <%
                    for (int i = 0; i < userFilters.size(); i++) {
                %>
                <input type="radio" name="filter"
                       value="<%=userFilters.get(i).getId()%>"><%=userFilters.get(i).getName()%>
                <br/>
                <%
                    }
                %>
                <button onclick="applyFilter();">Apply</button>
                
                <!--<button onclick="deleteFilter();">Delete filter</button>-->
            </fieldset>
        </form>
    </div>

public class ApplyFilterServlet extends HttpServlet {

    private ServletContext context;
    private List<EventTransfer> eventsTransfer = null;
    private HttpSession session = null;

    @Override
    public void init() throws ServletException {
        this.context = getServletContext();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        session = request.getSession();
        String action = request.getParameter("action");
        Integer targetId = null;
        try {
            targetId = Integer.parseInt(request.getParameter("id"));
        }
        catch (NumberFormatException e){
            context.getRequestDispatcher("/error.jsp").forward(request, response);
        }
        StringBuffer stringBuffer = new StringBuffer();

}
}

<servlet>
        <servlet-name>ApplyFilterServlet</servlet-name>
        <servlet-class>controller.ApplyFilterServlet</servlet-class>
    </servlet>

<servlet-mapping>
        <servlet-name>ApplyFilterServlet</servlet-name>
        <url-pattern>/applyfilter</url-pattern>
    </servlet-mapping>

function applyFilter(){
    idFilterJS = getRadioValue();
    var url = "applyfilter";
    var data = "applyfilterXML&id=" + idFilterJS;
    req = initRequest();
    req.open("GET", url, true);
    req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    req.onreadystatechange = applyFilterCallBack;
    req.send(data);
}

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

BufferedReader reader;
        reader = request.getReader();
        String str = "";
        String str2 = "";
        while ((str2 = reader.readLine()) != null){
            str = str + str2;
        }
     }

try {
        idFilterJS = getRadioValue();
        var url = "applyfilter?applyfilterXML&id=" + idFilterJS;
//    var data = "applyfilterXML&id=" + idFilterJS
        req = initRequest();
        req.open("GET", url, true);
        req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        req.onreadystatechange = applyFilterCallBack;
        req.send();
    }
    catch (err) {}
    }