uniapp 保存网络图片到手机相册

<view class="green bor_green pad_t_b_4 pad_l_r_10 radius5" @tap="saveHttpImg(currentPayInfo.img)">保存图片</view>

//下载网络图片
    saveHttpImg(url){
    let _t = this;
       uni.downloadFile({
                        url:url, //仅为示例，并非真实的资源
                        success: (res) => {
                                if (res.statusCode === 200) {
                                        let file = res.tempFilePath;
                                        _t.save(file)
                                }
                        }
                });
            },
//保存图片到本地
            save(url){
              let _this = this;
                _this.$util._loading("保存中...");
                uni.saveImageToPhotosAlbum({
                    filePath: url,
                    success: () => {
                        uni.hideLoading();
                        _this.$util._toast("图片已保存");
                    },
                    fail: () => {
                        uni.hideLoading();
                        _this.$util._toast("保存失败");
                    },
                    complete: () => {
                    
                    }
                });
          },