DISCUZ架构:AJAX之ajax.js 函数之一

var Ajaxs = new Array();
function Ajax(recvType, statusId) {
        var aj = new Object();
        aj.statusId = statusId ? document.getElementById(statusId) : null;
        aj.targetUrl = '';
        aj.sendString = '';
        aj.recvType = recvType ? recvType : 'XML';
        aj.resultHandle = null; 

        aj.createXMLHttpRequest = function() {
                var request = false;
                if(window.XMLHttpRequest) {
                        request = new XMLHttpRequest();
                        if(request.overrideMimeType) {
                                request.overrideMimeType('text/xml');
                        }
                } else if(window.ActiveXObject) {
                        var versions = ['Microsoft.XMLHTTP', 'MSXML.XMLHTTP', 'Microsoft.XMLHTTP', 'Msxml2.XMLHTTP.7.0', 'Msxml2.XMLHTTP.6.0', 'Msxml2.XMLHTTP.5.0', 'Msxml2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP'];
                        for(var i=0; i<versions.length; i++) {
                                try {
                                        request = new ActiveXObject(versions[i]);
                                        if(request) {
                                                return request;
                                        }
                                } catch(e) {
                                        //alert(e.message);
                                }
                        }
                }
                return request;
        }
        aj.XMLHttpRequest = aj.createXMLHttpRequest(); 

这一段是想尽一切办法建立一个XMLHttpRequest对象，无论是什么浏览器都能通用了。调用的时候是一个函数Ajax，有两个传入函数recvType和statusId，recvType是ajax返回值的接受类型，有HTML和XML两种类型，Dz一般用的是XML类型；statusID这个是用来指示状态的div。

以下为引用的内容：     

aj.processHandle = function() {
                if(aj.statusId) {
                        aj.statusId.style.display = '';
                }
                if(aj.XMLHttpRequest.readyState == 1 && aj.statusId) {
                        aj.statusId.innerHTML = xml_http_building_link;
                } else if(aj.XMLHttpRequest.readyState == 2 && aj.statusId) {
                        aj.statusId.innerHTML = xml_http_sending;
                } else if(aj.XMLHttpRequest.readyState == 3 && aj.statusId) {
                        aj.statusId.innerHTML = xml_http_loading;
                } else if(aj.XMLHttpRequest.readyState == 4) {
                        if(aj.XMLHttpRequest.status == 200) {
                                for(k in Ajaxs) {
                                        if(Ajaxs[k] == aj.targetUrl) {
                                                Ajaxs[k] = null;
                                        }
                                } 

                                if(aj.statusId) {
                                        aj.statusId.innerHTML = xml_http_data_in_processed;
                                        aj.statusId.style.display = 'none';
                                }
                                if(aj.recvType == 'HTML') {
                                        aj.resultHandle(aj.XMLHttpRequest.responseText, aj);
                                } else if(aj.recvType == 'XML') {
                                        aj.resultHandle(aj.XMLHttpRequest.responseXML.lastChild.firstChild.nodeValue, aj);
                                }
                        } else {
                                if(aj.statusId) {
                                        aj.statusId.innerHTML = xml_http_load_failed;
                                }
                        }
                }
        } 

Ajax实例化后的对象aj的processHandle方法，作用当然就是处理ajax请求过程的函数。
具体作用有两点：

第一点，那就是对statusId这个div进行ajax请求过程全程提示，在这段代码的前三分之一的样子就是做这个用的。

注意在register.htm中有对过程的定义，以下的代码引用自./templates/default/register.htm 

var profile_seccode_invalid = '{lang register_profile_seccode_invalid}';
                var profile_secanswer_invalid = '{lang register_profile_secqaa_invalid}';
                var profile_username_toolong = '{lang register_profile_username_toolong}';
                var profile_username_tooshort = '{lang register_profile_profile_username_tooshort}';
                var profile_username_illegal = '{lang register_profile_username_illegal}';
                var profile_passwd_illegal = '{lang register_profile_passwd_illegal}';
                var profile_passwd_notmatch = '{lang register_profile_passwd_notmatch}';
                var profile_email_illegal = '{lang register_profile_email_illegal}';
                var profile_email_invalid = '{lang register_profile_email_invalid}';
                var profile_email_censor = '{lang register_profile_email_censor}';
                var profile_email_msn = '{lang register_profile_email_msn}';
                var doublee = parseInt('$doublee');
                var lastseccode = lastsecanswer = lastusername = lastpassword = lastemail = '';
                var xml_http_building_link = '{lang xml_http_building_link}';
                var xml_http_sending = '{lang xml_http_sending}';
                var xml_http_loading = '{lang xml_http_loading}';
                var xml_http_load_failed = '{lang xml_http_load_failed}';
                var xml_http_data_in_processed = '{lang xml_http_data_in_processed}'; 

这个便是statusId具体中要提示的文字了，之所以要这样写当然是为了方便多语言。              

第二点是最重要的，当XMLHttpRequest.status=200的时候，那么就表示请求成功并返回了东西，这个时候就用resultHandle这个函数对返回的东西进行处理，可以看到还是分为HTML和XML两种情况分别调用不同的方法，一个是responsText一个是responseXML。      

aj.get = function(targetUrl, resultHandle) {
                if(in_array(targetUrl, Ajaxs)) {
                        return false;
                } else {
                        arraypush(Ajaxs, targetUrl);
                }
                aj.targetUrl = targetUrl;
                aj.XMLHttpRequest.onreadystatechange = aj.processHandle;
                aj.resultHandle = resultHandle;
                if(window.XMLHttpRequest) {
                        aj.XMLHttpRequest.open('GET', aj.targetUrl);
                        aj.XMLHttpRequest.send(null);
                } else {
                        aj.XMLHttpRequest.open("GET", targetUrl, true);
                        aj.XMLHttpRequest.send();
                }
        } 

        aj.post = function(targetUrl, sendString, resultHandle) {
                if(in_array(targetUrl, Ajaxs)) {
                        return false;
                } else {
                        arraypush(Ajaxs, targetUrl);
                }
                aj.targetUrl = targetUrl;
                aj.sendString = sendString;
                aj.XMLHttpRequest.onreadystatechange = aj.processHandle;
                aj.resultHandle = resultHandle;
                aj.XMLHttpRequest.open('POST', targetUrl);
                aj.XMLHttpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
                aj.XMLHttpRequest.send(aj.sendString);
        }
        return aj;
}