js
参考：http://fex.baidu.com/ueditor/#qa-customurl

UE.Editor.prototype._bkGetActionUrl = UE.Editor.prototype.getActionUrl;
UE.Editor.prototype.getActionUrl = function(action) {
    if (action == 'uploadimage' || action == 'uploadscrawl' || action == 'uploadimage') {
        //自定义接口
        return '/upload.php';
    }
}

后端接口返回格式
参考：http://fex.baidu.com/ueditor/#dev-request_specification

{
    "state": "SUCCESS",
    "url": "upload/demo.jpg",
    "title": "demo.jpg",
    "original": "demo.jpg"
}