Ajax学习笔记(二)

最新推荐文章于 2025-07-21 23:03:53 发布

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最新推荐文章于 2025-07-21 23:03:53 发布

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分类专栏： Java 文章标签： ajax xmlhttprequest function string import button

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本文通过一个具体的示例对比了GET和POST两种HTTP请求方法的区别。使用JavaScript发起AJAX请求，并在Java后端处理请求参数，返回不同的响应结果。

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以GET 和POST两种方式提交数据,这里以tomcat为服务器

html文件:testhtml

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>动态查询显示结果
  </title>
  <script type="text/javascript">
   var xmlHttp;
   function createXMLHTTPRequest()
   {
    if(window.ActiveXObject)
    {
     xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
    else if(window.XMLHttpRequest)
    {
     xmlHttp=new XMLHttpRequest();
    }
   }
   function startRequest_GET()
   {
    createXMLHTTPRequest();
    var url="PostData?"+sqlfactory()+"&timeStamp="+new Date().getTime();
    xmlHttp.onreadystatechange=handleStateChange;
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null);
   }
   function startRequest_POST()
   {
    createXMLHTTPRequest();
    var url="PostData?timeStamp="+(new Date()).getTime();
    var sql=sqlfactory();

    xmlHttp.open("POST",url,true);
    xmlHttp.onreadystatechange=handleStateChange;
    xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded;");
    xmlHttp.send(sql);
   }
   function handleStateChange()
   {
    if(xmlHttp.readyState==4)
    {
     if(xmlHttp.status==200)
     {
      document.getElementById("selectdata").innerHTML=xmlHttp.responseText;
     }
    }
   }
   function sqlfactory()
   {
    return "firstName="+document.getElementById("firstName").value+"&middleName="+document.getElementById("middleName").value+"&birthday="+document.getElementById("birthday").value;
   }
   </script>
</head>
<body>

   <table>
    <tr>
     <td>姓:</td>
     <td><input type="text" name="firstName"></td>
    </tr>
    <tr>
     <td>名:</td>
     <td><input type="text" name="middleName"></td>
    </tr>
    <tr>
     <td>生日:</td>
     <td><input type="text" name="birthday"></td>
    </tr>
   </table>
  <form action="#">
  <input type="button" value="GetData" onclick="startRequest_GET();"/><br><br>
  <input type="button" value="PostData" onclick="startRequest_POST();"/><br><br>

  <div id="selectdata"></div>
</form>
</body>
</html>

java文件:PostData.java

import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class PostData extends HttpServlet
{
private void Go(HttpServletRequest req,HttpServletResponse res,String method)throws ServletException,IOException
{
  res.setContentType("text/xml");
  req.setCharacterEncoding("gb2312");
  res.setCharacterEncoding("gb2312");
  String firstName=req.getParameter("firstName");
  String middleName=req.getParameter("middleName");
  String birthday=req.getParameter("birthday");

  String responseText="你的名字 <font color='red'>"+firstName+ " " +middleName +"</font>.你的生日:<font color='blue'>" + birthday + "</font>.[Method:" + method + "]";
  res.getWriter().print(responseText);
}
protected void doGet(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
{
  Go(req,res,"GET");
}
protected void doPost(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
{
  Go(req,res,"POST");
}
}