Question

请原谅我，因为代码很乱。我还在学习。我需要从CSV文件下载带有URL扫描的图像。然而，我有2000+的URL与相同的域，我不认为服务器将让我拉动一切，因此我总是得到一些图像后的错误。我需要解决的问题 -
1）如何确保图像完全下载然后只有代码移动到下一个URL
2）如何编写更好的代码你的帮助表示赞赏。谢谢

var csv = require('fast-csv');
var Promise = require('bluebird');
var fs = require('fs'); 
var request = require('request');
var path = "test.csv";

var promiseCSV = Promise.method(function(path, options) {
  return new Promise(function(resolve, reject) {
    var records = [];
    csv
      .fromPath(path, options)
      .on('data', function(record) {
        records.push(record);
      })
      .on('end', function() {
        resolve(records);
        console.log('done');
      });
  });
});



var download = function(uri, filename, callback){
  request.head(uri, function(err, res, body){

    request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
  });
};


promiseCSV(path).then(function (records) {

for(i=0;i<records.length;i++)
  {     
        download(records[i][0],'img/'+records[i][1], function(){

        });
    }

});

Answer 1

这会一次限制您的请求。另一种选择是使用throttled-request来限制每单位时间的请求。

Private Sub btnImport_Click()

  Dim bookList As Workbook
  Dim mergeObj As Object, dirObj As Object, filesObj As Object, everyObj As Object

  Dim folderpath As String

  folderpath = Range("I5").Value

  If Range("I5").Value = "" Then
    MsgBox "Select the folder which contains the reports.", vbInformation, "Cannot Import."
    Range("I2").Select
  ElseIf FileFolderExists(folderpath) = False Then
  MsgBox "Selected Folder Does Not Exist.", vbInformation, "Cannot Import."
    Range("I5").Select
  ElseIf Dir(folderpath, vbDirectory) = "" Then
    MsgBox "Selected Folder Not Found.", vbInformation, "Invalid Folder Name."
    Range("I5").Select

  Else
    Me.lblWait.Visible = True
    Me.btnCancel.Visible = False
    Me.btnImport.Visible = False

    Application.ScreenUpdating = False
    Application.StatusBar = "Collecting Data, Please Wait..."
    Set mergeObj = CreateObject("Scripting.FileSystemObject")

    'change folder path of excel files here
    Set dirObj = mergeObj.Getfolder("folderpath")
    Set filesObj = dirObj.Files
    For Each everyObj In filesObj
    Set bookList = Workbooks.Open(everyObj)

    On Error Resume Next

    'Change B3:H to the range your working on and also B in B65536 to any column required.
     bookList.Worksheets(1).Range("B3:H350" & bookList.Worksheets(1).Range("B65536").End(xlUp).Row).Copy
     ThisWorkbook.Worksheets(1).Activate

  'Below only change "B" column name to your required column name
  Range("B65536").End(xlUp).Offset(1, 0).PasteSpecial xlPasteValues
  Application.CutCopyMode = False
  bookList.Close
  Next

  End If
End Sub

此外，您的记录变量超出范围，您需要将其移出才能访问它：

var i = 0;
promiseCSV(path).then(function (records) {
  next();
  function next(){
    download(records[i][0],'img/'+records[i][1], function(){
      i++;
      if (i < records.length) next();
    });
  }
});

使用带CSV扫描的节点请求下载图像

1 个答案: