ASP.NET技巧：创建不了XMLHTTP控件

最近在用ajax开发服务器程序，发现ie浏览器不支持xmlhttprequest对象，而且找不到microsoft.xmlhttp控件。

问题出现了我们需要解决，解决方案如下：

1、运行下regsvr32 msxml3.dll；
2、用现成的框架来做ajax；
3、代码优化：

if(window.activexobject)
    {
        xmlhttp = new activexobject("microsoft.xmlhttp");
    }
    else if(window.xmlhttprequest)
    {
        xmlhttp = new xmlhttprequest();
    }

    if(handle_s == null)
        handle_s = "bin/normal.py/db";
    this.xmlhttp.onreadystatechange = handle_l;
    this.xmlhttp.open("get",handle_s,true);
    this.xmlhttp.send(null);

或判断浏览器

var agt = navigator.useragent.tolowercase();
var is_ie = (agt.indexof("msie") != -1);
var is_ie5 = (agt.indexof("msie 5") != -1);
var is_opera = (agt.indexof("opera") != -1);
var is_mac = (agt.indexof("mac") != -1);
var is_gecko = (agt.indexof("gecko") != -1);
var is_safari = (agt.indexof("safari") != -1);

function createxmlhttpreq(handler) {

var xmlhttp = null;
if (is_ie) {
// guaranteed to be ie5 or ie6
var control = (is_ie5) ? "microsoft.xmlhttp" : "msxml2.xmlhttp";

try {
xmlhttp = new activexobject(control);
xmlhttp.onreadystatechange = handler;
} catch (ex) {
// todo: better help message
alert("you need to enable active scripting and activex controls");
}

} else {

// mozilla
xmlhttp = new xmlhttprequest();
xmlhttp.onload = handler;
xmlhttp.onerror = handler;

}

return xmlhttp;
}

或者

<script language="javascript">
    var http_request = false;
    function send_request(url) {//初始化、指定处理函数、发送请求的函数
        http_request = false;
        //开始初始化xmlhttprequest对象
        if(window.xmlhttprequest) { //mozilla 浏览器
            http_request = new xmlhttprequest();
            if (http_request.overridemimetype) {//设置mime类别
                http_request.overridemimetype('text/xml');
            }
        }
        else if (window.activexobject) { // ie浏览器
            try {
                http_request = new activexobject("msxml2.xmlhttp");
            } catch (e) {
                try {
                    http_request = new activexobject("microsoft.xmlhttp");
                } catch (e) {}
            }
        }
        if (!http_request) { // 异常，创建对象实例失败
            window.alert("不能创建xmlhttprequest对象实例.");
            return false;
        }
        http_request.onreadystatechange = processrequest;
        // 确定发送请求的方式和url以及是否同步执行下段代码
        http_request.open("get", url, true);
        http_request.send(null);
    }
    // 处理返回信息的函数
    function processrequest() {
        if (http_request.readystate == 4) { // 判断对象状态
            if (http_request.status == 200) { // 信息已经成功返回，开始处理信息
                var returnobj = http_request.responsexml;
                var xmlobj = http_request.responsexml;
                var employees = xmlobj.getelementsbytagname("employee");
                var feedbackstr = "";
                for(var i=0;i<employees.length;i++) { // 循环读取employees.xml的内容
                    var employee = employees[i];
                    feedbackstr += "员工：" + employee.getattribute("name");//取得标签指定属性
                    feedbackstr += " 职位：" + employee.getelementsbytagname("job")[0].firstchild.data;//取得指定标签的最初数据
                    feedbackstr += " 工资：" + employee.getelementsbytagname("salary")[0].firstchild.data;
                    feedbackstr +=  "/r/n";
                }
                alert(feedbackstr);
            } else { //页面不正常
                alert("您所请求的页面有异常。");
            }
        }
    }
</script>