$.get("http://localhost:8080/JQueryStudy/UserVerify?userName=" + encodeURI(encodeURI(userName)),null,
          function(response){
            $("#result").html(response);
          }
        )

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package com.linying;

import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 用户名验证Servlet
 * @author Ying-er
 * @time 2010-4-25下午08:02:08
 * @version 1.0
 */
public class UserVerify extends HttpServlet {
  
  /** 
  * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
  * @param request servlet request
  * @param response servlet response
  */
  protected void processRequest(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();
    try {
      String param = request.getParameter("userName");
      if (param == null || param.length() == 0) {
        out.println("用户名不能为空");
      } else {
        String userName = URLDecoder.decode(param, "UTF-8");
        System.out.println(userName);
        if (userName.equals("Ying-er")) {
          out.println("用户名[" + userName + "]已经存在，请使用别的用户名注册");
        } else {
          out.println("可以使用用户名[" + userName + "]注册");
        }
      }
    } finally { 
      out.close();
    }
  } 

  // <editor-fold defaultstate="collapsed" desc="HttpServlet">
  /** 
  * Handles the HTTP <code>GET</code> method.
  * @param request servlet request
  * @param response servlet response
  */
  protected void doGet(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {
    processRequest(request, response);
  } 

  /** 
  * Handles the HTTP <code>POST</code> method.
  * @param request servlet request
  * @param response servlet response
  */
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {
    processRequest(request, response);
  }

  /** 
  * Returns a short description of the servlet.
  */
  public String getServletInfo() {
    return "Short description";
  }// </editor-fold>

}