安卓端数据导出成txt文件

  toExport() {
      if (this.dataList == false) {
        this.$createDialog({
          type: "alert",
          content: "数据為空",
          confirmBtn: "確定",
          icon: "cubeic-alert"
        }).show();
      } else {
        var that = this;
        this.$createDialog({
          type: "confirm",
          icon: "cubeic-alert",
          content: "確定導出嗎？",
          confirmBtn: {
            text: "確定",
            active: true,
            disabled: false,
            href: "javascript:;"
          },
          cancelBtn: {
            text: "取消",
            active: false,
            disabled: false,
            href: "javascript:;"
          },
          onConfirm: () => {
            var data = [];
            this.dataList.forEach(x => {
              var datas = x.counter + "," + x.barcode + "," + x.qty + "\n";
              //var datas = x.counter + "," + x.barcode + "," + x.qty;
              data.push(datas);
            });
            //合并数组为字符串
            var temp_string = data.join("");
            //alert(temp_string)
            //alert(window.requestFileSystem)

            window.requestFileSystem(
              LocalFileSystem.PERSISTENT,
              ,
              function(fs) {
                //alert("open: " + fs.name);
                fs.root.getFile(
                  "stocking.txt",
                  { create: true, exclusive: false },
                  function(fileEntry) {
                    //alert(fileEntry);
                    //alert("is file？" + fileEntry.isFile.toString());
                    //文件内容
                    //alert (typeof temp_string)
                    // alert("插入的内容是"+temp_string)
                    var dataObj = new Blob([temp_string], {
                      type: "text/plain"
                    });
                    // var dataObj2 = new Blob(["temp_string"], {
                    //   type: "text/plain"
                    // });
                    //写入文件
                    that.writeFile(fileEntry, dataObj);
                    //that.writeFile(fileEntry, dataObj2);
                  },
                  that.onErrorCreateFile
                );
              },
              that.onErrorLoadFs
            );
          }
        }).show();
      }
      //持久化数据保存
    },
    writeFile(fileEntry, dataObj) {
       var that=this;
      //创建一个写入对象
      fileEntry.createWriter(function(fileWriter) {
        //文件写入成功
        fileWriter.onwriteend = function() {
           that.contents="數據保存成功";
           that.showPopup();
        };

        //文件写入失败
        fileWriter.onerror = function(e) {
          that.contents="數據保存失敗";
           that.showPopup();
        };

        //写入文件
        fileWriter.write(dataObj);
      });
    },