Ajax做进度条的问题(已解决) - 编程论坛

《Ajax基础教程》上有个例子做进度条的，我按照它的代码写，运行的时候就是看不见这个进度条，但是到了时间会显示Complete!。求助...
progressBar.jsp:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Progress Bar Test</title>
<script>
    var xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    var key;
    var bar_color = "blue";
    var span_id = "block";
    var clear = "???";

    function go() {
        checkDiv();
        var url = "ProgressBarServlet?task=create";
        var button = document.getElementById("go");
        button.disabled = true;
        xmlHttp.open("GET", url, true);
        xmlHttp.onreadystatechange = goCallback;
        xmlHttp.send(null);
    }

    function goCallback() {
        if (xmlHttp.readyState == 4) {
            if (xmlHttp.status == 200) {
                setTimeout("pollServer()", 1000);
            }
        }
    }

    function pollServer() {
        var url = "ProgressBarServlet?task=poll&key=" + key;
        xmlHttp.open("GET", url, true);
        xmlHttp.onreadystatechange = pollCallback;
        xmlHttp.send(null);
    }

    function pollCallback() {
        if (xmlHttp.readyState == 4) {
            if (xmlHttp.status == 200) {
                var percent_complete = xmlHttp.responseXML.getElementsByTagName("percent")[0].firstChild.data;
                var index = processResult(percent_complete);
                for (var i = 1; i <= index; i++) {
                    var elem = document.getElementById("block" + i);
                    elem.innerHTML = clear;
                    elem.style.backgroundColor = bar_color;
                    var next_cell = i + 1;
                    if (next_cell > index && next_cell <= 9) {
                        document.getElementById("block" + next_cell).innerHTML = percent_complete + "%";
                    }
                }
                if (index < 9) {
                    setTimeout("pollServer()", 1000);
                } else {
                    document.getElementById("complete").innerHTML = "Complete!";
                    document.getElementById("go").disabled = false;
                }
            }
        }
    }

    function processResult(percent_complete) {
        var ind;
        if (percent_complete.length == 1) {
            ind = 1;
        } else if (percent_complete.length == 2) {
            ind = percent_complete.substring(0, 1);
        } else {
            ind = 9;
        }
        return ind;
    }

    function checkDiv() {
        var progress_bar = document.getElementById("progressBar");
        if (progress_bar.style.visibility == "visible") {
            clearBar();
            document.getElementById("complete").innerHTML = "";
        } else {
            progress_bar.style.visiblity = "visible";
        }
    }

    function clearBar(){
        for (var i = 0; i < 10; i++) {
            var elem = document.getElementById("block" + i);
            elem.innerHTML = clear;
            elem.style.backgroundColor = "red";
        }
    }

</script>
</head>
<body>
<h1>Ajax Progress Bar Example</h1><br/>
Launch long-running process:
<input type="button" value="Launch" id="go" onclick="go();" /><br/>
<table align="center">
    <tbody>
        <tr>
            <td>
                <div id="progressBar" style="padding:2px;border:solid black 2px;visibility:hidden">
                    <span id="block1">???</span>
                    <span id="block2">???</span>
                    <span id="block3">???</span>
                    <span id="block4">???</span>
                    <span id="block5">???</span>
                    <span id="block6">???</span>
                    <span id="block7">???</span>
                    <span id="block8">???</span>
                    <span id="block9">???</span>
                </div>
            </td>
        </tr>
        <tr>
            <td id="complete" align="center"></td>
        </tr>
    </tbody>
</table>
</body>
</html>

ProgressBarServlet.java:
package src;

import
import

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

public class ProgressBarServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {

    private int counter = 1;

    public ProgressBarServlet() {
        super();
    }


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        String task = request.getParameter("task");
        String res = "";
        if (task.equals("create")) {
            res = "<key>1</key>";
            counter = 1;
        } else {
            String percent = "";
            switch (counter) {
            case 1: percent = "10"; break;
            case 2: percent = "23"; break;
            case 3: percent = "35"; break;
            case 4: percent = "51"; break;
            case 5: percent = "64"; break;
            case 6: percent = "73"; break;
            case 7: percent = "89"; break;
            case 8: percent = "100"; break;
            }
            counter++;
            res = "<percent>" + percent + "</percent>";
        }

        PrintWriter out = response.getWriter();
        response.setContentType("text/xml");
        response.setHeader("Cache-Control", "no-cache");
        out.println("<response>");
        out.println(res);
        out.println("</response>");
        out.close();
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

[[italic] 本帖最后由 hwoarangzk 于 2008-1-9 16:21 编辑 [/italic]]