AJAX+Servlet實現的數據處理顯示功能示例

%@ 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 的幾個步驟：
    1、建立XmlHttpRequest對象
    2、設置回調函數
    3、使用Open方法建立與服務器的連接
    4、向服務器發(fā)送數據
    5、在回調函數中針對不同響應狀態(tài)進行處理
  */
    var xmlHttp;
    function createXMLHttpRequest(){  //1建立XmlHttpRequest對象
      if(window.ActiveXObject){
        try{
          xmlHttp = new ActiveXObject("Microsoft.XMLHttp");
        }catch(e){
          alert("Error!!!");
        }
      }else{
        xmlHttp = new XMLHttpRequest();
      }
    }
    function showMes(){   //2設置回調函數
      if(xmlHttp.readyState==4){ //數據接收完成并可以使用
        if(xmlHttp.status==200){ //http狀態(tài)OK
        //5、在回調函數中針對不同響應狀態(tài)進行處理
          document.getElementById("sp").innerHTML = xmlHttp.responseText; //服務器的響應內容
        }else{
          alert("出錯："+xmlHttp.statusText); //HTTP狀態(tài)碼對應的文本
        }
      }
    }
    /**
    //這是GET方法傳送
    function getMes(){
      createXMLHttpRequest();
      var txt = document.getElementById("txt").value;
      var url="servlet/AjaxServlet?txt="+txt;
      url = encodeURI(url); //轉換碼后再傳輸
      xmlHttp.open("GET",url,true); //3使用Open方法建立與服務器的連接
      xmlHttp.onreadystatechange=showMes;
      xmlHttp.send(null); //4向服務器發(fā)送數據
    }
    */
    /**
    *這是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轉換獲得傳輸過來的碼
    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();
}