前端将后台返回的数据流转为图片

var xmlhttp;
xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET",userUrl2 + 'user/getQrCode'+accessToken+"&name="+item.name+"&phone="+item.phoneNumber+"&company="+item.companyName,true);
xmlhttp.responseType = "arraybuffer";
xmlhttp.onload = function(){
    // console.log(this);
    var res=this.response;
    if (this.status == 200) {
        var code = 'data:image/png;base64,' + btoa(new Uint8Array(res).reduce((data, byte) => data + String.fromCharCode(byte), ''))
        editMode.find('#edit-BelongCard').attr('src', code)
    }
}
xmlhttp.send();



稍微改动过：

var xmlhttp;
xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET",userUrl2 + 'user/getQrCode'+accessToken+"&name="+item.name+"&phone="+item.phoneNumber+"&company="+item.companyName,true);
xmlhttp.responseType = "arraybuffer";
xmlhttp.onload = function(){
    // console.log(this);
    var res=this.response;
    if (this.status == 200) {
        // var code = 'data:image/png;base64,' + btoa(new Uint8Array(res).reduce((data, byte) => data + String.fromCharCode(byte), ''))
        var bytes = new Uint8Array(res);
        var storeData = "";
        var len = bytes.byteLength;
        for (var i = 0; i < len; i++) {
            storeData += String.fromCharCode(bytes[i]);
        }
        var code='data:image/png;base64,'+ window.btoa(storeData);
        common.find('#detail-businessCardFront').attr('src', code);//专属凭证
    }
}
xmlhttp.send();