Ajax-java中的ajax使用，以及编码问题

<script type="text/javascript" src="js/AjaxRequest.js"></script>

<script type="text/javascript">
var xhr = Ajax();

var url = "IsExistUserAjaxServlet";
var params = "name=张三&age=12&sex=woman";

/* GET */
var des_url_get = url + "?nocache=" + new Date().getTime() + "&" + params;
xhr.get(des_url_get, function(data) {
console.log(data);
});

/* POST*/
/* var des_url_post = url + "?nocache=" + new Date().getTime();
xhr.post(des_url_post, params, function(data) {
console.log(data);
}); */
</script>

package com.gordon.servlet;

import java.io.IOException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(name = "IsExistUserAjaxServlet", urlPatterns = { "/IsExistUserAjaxServlet" })
public class IsExistUserAjaxServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

public IsExistUserAjaxServlet() {
super();
}

public void init(ServletConfig config) throws ServletException {
}

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

request.setCharacterEncoding("UTF-8");
response.setContentType("text/text;charset=utf-8");

String name = request.getParameter("name");
String sex = request.getParameter("sex");
int age = Integer.valueOf(request.getParameter("age"));

System.out.println(name + ", " + sex + ", " + age);

response.getWriter().println("name:" + name + "age:" + age + "sex:" + sex);
}

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