Ajax与servlet交互的实例【转】

1、JavaScript代码

 

 

var req; /*通过异步传输XMLHTTP发送参数到ajaxServlet，返回符合条件的XML文档*/ var url; function getResult() {     var f=document.getElementById("form_pub");   var key=f.s.options[f.s.selectedIndex].text; //获取对select中文本的引用  if (window.XMLHttpRequest)  {   req = new XMLHttpRequest();   url = "ajaxServlet?action="+key+"&bm=UTF-8"; }else if (window.ActiveXObject)  {     req = new ActiveXObject("Microsoft.XMLHTTP");    url = "ajaxServlet?action="+key+"&bm=gbk";  }  if(req)  {     req.open("GET",url, true);     req.setRequestHeader("Content-Type", "text/html;charset=UTF-8");    //这里如果不设定头部则会导致 firfox 发送数据错误，servlet接受到的参数为乱码，在IE中正常   req.onreadystatechange = complete;     req.send(null);   //req.setRequestHeader("Content-Type", "text/xml; charset=UTF-8");   } } /*分析返回的XML文档*/ function complete(){  if (req.readyState == 4)  {    if (req.status == 200)    {      var items=document.getElementById("belong");    //以下为解析返回的XML文档         var xmlDoc = req.responseXML;      var Node=xmlDoc.getElementsByTagName("type_name");      //var str=new Array();       var str=null;       //清空工作        items.innerHTML=""; //删除一个 select内的全部内容  for(var i=0;i<Node.length;i++)       {           str=Node[i];          //alert(str.childNodes[0].nodeValue);          var objectOption=document.createElement("option");           items.options.add(objectOption);          //firfox不支持innerText必须用textContent代替           if (window.ActiveXObject)           {objectOption.innerText=str.childNodes[0].nodeValue;}           else           {objectOption.textContent=str.childNodes[0].nodeValue;}       }     }   }  }

 

 

2、Servlet代码

 

package ajax;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import Data_GetConn.GetConn;//这个包是自己写的为获取对mysql的引用import java.sql.*;//这个包必须有！！public class ajaxServlet extends HttpServlet{ //private static final String CONTENT_TYPE = "text/xml; charset=UTF-8";//这里最好统一用UTF-8进行编码 public void init() throws ServletException{} public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {  response.setContentType("text/xml; charset=UTF-8");  //以下两句为取消在本地的缓存  response.setHeader("Cache-Control", "no-cache");   response.setHeader("Pragma", "no-cache");  PrintWriter out = response.getWriter();  String action = request.getParameter("action");  String bm = request.getParameter("bm");    if(("gbk").equals(bm))  {    action=new String(action.getBytes("ISO-8859-1"),"gbk");//将获得的数据用gbk从新编码！（感谢董卫老师）  }  else  {      action=new String(action.getBytes("ISO-8859-1"),"gbk");  }  try    {      GetConn wq=new GetConn();      Connection     con=wq.getCon();      Statement stmt=con.createStatement();      ResultSet rs=stmt.executeQuery("select items from class where main='"+action+"'");      StringBuffer sb = new StringBuffer();       sb.append("<type>");     while(rs.next())      {                 sb.append("<type_name>"+rs.getString(1)+"</type_name>");               }        //sb.append("<type_name>"+action+"</type_name>");        sb.append("</type>");         out.write(sb.toString());//注意这里向jsp输出的流，在script中的截获方法        out.close();        stmt.close();        con.close();    }    catch(Exception ex)    {             }   }}

 

 

原文章：Ajax与servlet交互的实例