为何安卓下从相册选择图片的filename指定路径没有用

function galleryImg() {  
                // 从相册中选择图片  
                console.log("从相册中选择图片:");  
                plus.gallery.pick(function(path) {  
                    console.log(path);  
                    showImg(path);  
                }, function(e) {  
                    console.log("取消选择图片");  
                }, {  
                    filename: "_doc/image/head" + new Date().getTime() + ".jpg",  
                    filter: "image"  
                });  
            }