ajax问题

DHUEUADADF 2011-03-14 09:45:28

makepaper.jsp代码:

<%@ page language="java" import="java.util.*,java.sql.*,com.yidi.test.*"
pageEncoding="gb2312"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'MakePaper.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">


</head>
<script type="text/javascript">
function getResult(stateVal) {

var url = "servlet/Point?subject="+stateVal;

if (window.XMLHttpRequest) {
req = new XMLHttpRequest();
}else if (window.ActiveXObject) {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
if(req){
req.open("GET",url, true);
req.onreadystatechange = complete;
req.send(null);
}

}
function complete(){
if (req.readyState == 4) {
if (req.status == 200) {
alert("url");
var city = req.responseXML.getElementsByTagName("point");

//alert(city.length);
var str=new Array();
for(var i=0;i<city.length;i++){
str[i]=city[i].firstChild.data;
}
//alert(document.getElementById("city"));
buildSelect(str,document.getElementById("point"));
}
}
}
function buildSelect(str,sel) {
sel.options.length=0;
for(var i=0;i<str.length;i++) {
sel.options[sel.options.length]=new Option(str[i],str[i])
}
}
</script>
<body>
<H2>
组卷
</H2>
<Br />

设置试卷号:
<input type="text" name="paperno" />
选择科目类型:
<select name="subject" onChange="getResult(this.value)" >
<%
OpenDB od = new OpenDB();
ResultSet rs = od
.executeQuery("select distinct psubject from paperRules");
try {

while (rs.next()) {
String s = rs.getString(1);
%>
<option value=<%=s%>><%=s%></option>
<%
}

} catch (Exception e) {
e.printStackTrace();

} finally {
od.close();

}
%>
</select>

<select name="point" id="point">
<option selected>===知识点===</option>
</select>
<br />

</body>
</html>

============================================================================================
point.java代码:

package com.yidi.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;

import com.yidi.test.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Point extends HttpServlet {

/**
* Constructor of the object.
*/
public Point() {
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.setContentType("text/xml");

response.setHeader("Cache-Control", "no-cache");
request.setCharacterEncoding("GBK");
response.setCharacterEncoding("utf-8");
String s=request.getParameter("subject");
String PaperNo=request.getParameter("paperno");
s=new String(s.getBytes("iso-8859-1"),"gb2312");
PaperNo=new String(PaperNo.getBytes("iso-8859-1"),"gb2312");

OpenDB od=new OpenDB();
ResultSet rs=od.executeQuery("select distinct pointName from point where subject='"+s+"'");
StringBuffer sb=new StringBuffer("<state>");
try{
while(rs.next()){

String pointName=rs.getString(1);//得到pointName

sb.append("<point>pointName</point>");
}
}catch(Exception e){
e.printStackTrace();

}

sb.append("</state>");
PrintWriter out=response.getWriter();
out.write(sb.toString());
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 {

this.doGet(request, response);
}

/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}

}

我连了数据库。但得到不到结果：高手分析下

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