如何上传图片流，不是本地图片

/**  
 * 单利模式，上传工具  
 */  
;  
var uploadp = (function() {  
    var instance = null;  

    function getInstance(options) {  
        if(instance == null) {  
            instance = new myobj(options);  
            console.log("new instance");  
            return instance;  
        } else {  
            return instance;  
        }  
    }  

    function myobj(options) {  
        this.serverPath = "服务器路径";  
        this.fileList = options.fileList;  
        this.params = {}; //参数  
    }  

    var proto = myobj.prototype;  

    proto.before = function() {  
        var self = this;  
        var serverUrl = zlapp.serverPath() + "/UploadAllServlet?i=" + Math.random();  
        zlapp.ajax(serverUrl, {}, function(data) {  
            var param = {  
                key: "123.png",  
                policy: data.policy,  
                OSSAccessKeyId: data.accessid,  
                success_action_status: "200",  
                signature: data.signature  
            };  
            self.params = param;  
        }, "", {  
            async: false  
        })  
    }  
    proto.upload = function() {  
        var self = this;  
        self.before();  
        var formData = new FormData();  
        var key = "";  
        var filename = self.fileList[0];  
        var suffix = filename.substring(filename.lastIndexOf("."), filename.length);  
        filename = "picture/" + self.getDate() + "/" + self.getTimestamp() + suffix;  
        self.params.key = filename;  
        alert(JSON.stringify(self.params));  
        for(key in self.params) {  
            var paramValue = self.params[key];  
            formData.append(key, paramValue);  
        }  

        var xhr = new XMLHttpRequest();  
        xhr.onreadystatechange = function(e) {  
            if(xhr.readyState == "4" && this.status == 200) { //上传成功    
                console.log(self.serverPath + "/" + filename);  
                mui.toast("上传成功");  
                // 图片预览  
            } else {  
                //mui.toast("上传失败");  
            }  
        }  
        //进度监听  
        xhr.upload.addEventListener("progress", function(evt) {  
            if(evt.lengthComputable) {  
                var percentComplete = Math.round(evt.loaded * 100 / evt.total);  
                document.getElementById("upload111").innerText = percentComplete.toString() + '%';  
            } else {  
                mui.toast("unable to compute");  
            }  
        }, false);  

        xhr.open('POST', this.serverPath);  
        formData.append("file", self.fileList[0]);  
        xhr.send(formData);  
    };  

    proto.getDate = function(htm) {  
        var myDate = new Date();  
        var year = myDate.getFullYear();  
        var month = Number(myDate.getMonth()) + 1;  
        month = month < 10 ? ("0" + month) : month;  
        return year + "-" + month;  
    };  

    proto.getTimestamp = function() {  
        return new Date().getTime();  
    };  

    return getInstance;  
})();  

/****************************************  
如何使用  
new uploadp({  
    fileList: files  
}).upload();  
****************************************/