xmlhttprequest.js

Ajax實現檔案上傳功能,ajax file upload

var oRequest;
var readedPercent = 1;

if (typeof XMLHttpRequest == "undefined" && window.ActiveXObject) {
    function XMLHttpRequest() {

        var arrSignatures = ["MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0",
                             "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP",
                             "Microsoft.XMLHTTP"];
                         
        for (var i=0; i < arrSignatures.length; i++) {
            try {
        
                var oReq = new ActiveXObject(arrSignatures[i]);
            
                return oReq;
        
            } catch (oError) {
                //ignore
            }
        }          

        throw new Error("MSXML is not installed on your system.");               
    }
}

function addPostParam(sParams, sParamName, sParamValue) {
	if(sParams.length > 0) {
		sParams += "&";
	}
	
	return sParams + encodeURIComponent(sParamName) + "=" + encodeURIComponent(sParamValue);
}

function getProgressInfo() {
    oRequest = new XMLHttpRequest();
    oRequest.onreadystatechange = ProcessResponse;
    oRequest.open("post", "FileUploadServlet", true);
    oRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    var sParams = "";
    sParams = addPostParam(sParams, "GetUploadedPercentage", "YES");
    oRequest.send(sParams);
}

function ProcessResponse() {

	if(oRequest.readyState == 4) {
		var oProgressInfo = eval('(' + oRequest.responseText + ')');
	    readedPercent = parseInt(oProgressInfo.Percent);
	    
	    if(readedPercent == "100") {
		    document.getElementById("ProgressText").innerHTML = readedPercent + "% uploaded, please wait...";
		} else {
			document.getElementById("ProgressText").innerHTML = readedPercent + "% uploaded...";
	    }
	    
	    document.getElementById("ProgressBar").style.width = readedPercent + "%";
	}
}