Servlet+AJAX实现数据处理显示
实现功能：在输入框中输入字符，用AJAX传到后台Servlet处理后加上随机数，并返回到前台显示。
一、写前台jsp页面index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>My JSP 'index.jsp' starting page</title> <script type="text/javascript">/*ajax 的几个步骤：1、建立XmlHttpRequest对象2、设置回调函数3、使用Open方法建立与服务器的连接4、向服务器发送数据5、在回调函数中针对不同响应状态进行处理*/var xmlHttp;function createXMLHttpRequest(){ //1建立XmlHttpRequest对象if(window.ActiveXObject){try{xmlHttp = new ActiveXObject("Microsoft.XMLHttp");}catch(e){alert("Error!!!");}}else{xmlHttp = new XMLHttpRequest();}}function showMes(){//2设置回调函数if(xmlHttp.readyState==4){ //数据接收完成并可以使用if(xmlHttp.status==200){ //http状态OK//5、在回调函数中针对不同响应状态进行处理document.getElementById("sp").innerHTML = xmlHttp.responseText; //服务器的响应内容}else{alert("出错："+xmlHttp.statusText); //HTTP状态码对应的文本}}}/**//这是GET方法传送function getMes(){createXMLHttpRequest();var txt = document.getElementById("txt").value;var url="servlet/AjaxServlet?txt="+txt;url = encodeURI(url); //转换码后再传输xmlHttp.open("GET",url,true); //3使用Open方法建立与服务器的连接xmlHttp.onreadystatechange=showMes; xmlHttp.send(null); //4向服务器发送数据}*//***这是post方法*/function postMes(){createXMLHttpRequest();var txt = document.getElementById("txt").value;var url = "servlet/AjaxServlet";var params = "username="+txt;//alert(params);xmlHttp.open("POST",url,true);xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=UTF-8");xmlHttp.send(params);xmlHttp.onreadystatechange = showMes;}</script> </head> <body> <input type="text" id="txt"/> <input type="button" value="query" onclick="postMes()" /> <span id="sp"></span> </body></html>public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {request.setCharacterEncoding("utf-8"); //用utf-8转换获得传输过来的码response.setContentType("text/html");PrintWriter out = response.getWriter();String txt = request.getParameter("txt");//String tx = new String(txt.getBytes("iso-8859"),"utf-8");out.print("txt="+txt+Math.random());out.flush();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 {request.setCharacterEncoding("utf-8");response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();String username = request.getParameter("username");//String txt = new String(username.getBytes("ISO-8859-1"),"UTF-8");String txt = new String(username);out.print("txt="+txt+":"+Math.random());out.flush();out.close();}