使用ajax定时显示消息

package duyongyao.servlet; import java.io.IOException; import java.io.PrintWriter; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import duyongyao.dao.MessagesDao; import duyongyao.entity.Messages; public class AjaxServlet extends HttpServlet { /** * Constructor of the object. */ public AjaxServlet() { super(); } /** * Destruction of the servlet. <br> */ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } /** * The doGet method of the servlet. <br> * * This method is called when a form has its tag value method equals to get. * * @param request * the request send by the client to the server * @param response * the response send by the server to the client * @throws ServletException * if an error occurred * @throws IOException * if an error occurred */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setHeader("Cache-Control", "no-cache"); // HTTP 1.1 response.setHeader("Pragma", "no-cache"); // HTTP 1.0 response.setDateHeader("Expires", 0); response.setContentType("text/html;charset=GBK"); MessagesDao dao = new MessagesDao(); String contentToBack = ""; List list = dao.getMessages(); for (int i = 0; i < list.size(); i++) { contentToBack += ((Messages) list.get(i)).getContent(); } PrintWriter out = response.getWriter(); //out.println(java.net.URLEncoder.encode(contentToBack,"UTF-8")); out.println(contentToBack); out.close(); } /** * The doPost method of the servlet. <br> * * This method is called when a form has its tag value method equals to * post. * * @param request * the request send by the client to the server * @param response * the response send by the server to the client * @throws ServletException * if an error occurred * @throws IOException * if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } /** * Initialization of the servlet. <br> * * @throws ServletException * if an error occure */ public void init() throws ServletException { // Put your code here } }