在本教程中，我们将介绍如何实现文档转换套件的异步方法。您只需将源文档发送到 SubmitTIFFConversionTask 或 SubmitPDFConversionTask API 方法即可接收任务标识符作为响应。还有SubmitDOCXConversionTask方法将PDF文档转换为可编辑的Microsoft Word文档。

收到任务标识符后，您需要通过调用 GetConversionTaskStatus 方法检查任务状态。只要任务状态等于“Waiting”，您需要在几秒钟延迟后调用相同的方法。一旦您从GetConversionTaskStatus方法收到“Completed”，您可以调用DownloadResult方法来下载最终文档文件。您可以使用下面的 Visual Basic 实现。

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Imports System
Imports System.IO
Imports System.Net.Http

Module Program
    Async Function SubmitPdfConversionTask(filePathToConvert As String, rapidApiKey As String) As Task(Of String)
        Using httpClient As New HttpClient()
            Using form As New MultipartFormDataContent()
                form.Headers.Add("X-RapidAPI-Key", rapidApiKey)
                form.Add(New StringContent("Sebastian"), "authorName")
                form.Add(New StringContent("Final report"), "title")
                form.Add(New StringContent("Reports, Final"), "keywords")
                form.Add(New StringContent("Quarterly Final Report"), "name")
								
                Dim fileBytes = Await File.ReadAllBytesAsync(filePathToConvert)
                Dim fileName = Path.GetFileName(filePathToConvert)
                form.Add(New ByteArrayContent(fileBytes, 0, fileBytes.Length), "file", fileName)

                Using response = Await httpClient.PostAsync("https://petadata-document-conversion-suite.p.rapidapi.com/SubmitPDFConversionTask", form)
                    response.EnsureSuccessStatusCode()
                    Return Await response.Content.ReadAsStringAsync()
                End Using
            End Using
        End Using
    End Function
		
    Async Function GetConversionTaskStatus(taskId As String, rapidApiKey As String) As Task(Of String)
        Using httpClient As New HttpClient()
            httpClient.DefaultRequestHeaders.Add("X-RapidAPI-Key", rapidApiKey)
            Using response = Await httpClient.GetAsync($"https://petadata-document-conversion-suite.p.rapidapi.com/GetConversionTaskStatus?taskId={taskId}")
                response.EnsureSuccessStatusCode()
                Return Await response.Content.ReadAsStringAsync()
            End Using
        End Using
    End Function
		
    Async Function DownloadResult(taskId As String, rapidApiKey As String) As Task(Of Byte())
        Using httpClient As New HttpClient()
            httpClient.DefaultRequestHeaders.Add("X-RapidAPI-Key", rapidApiKey)
            Using response = Await httpClient.GetAsync($"https://petadata-document-conversion-suite.p.rapidapi.com/DownloadResult?taskId={taskId}")
                response.EnsureSuccessStatusCode()
                Return Await response.Content.ReadAsByteArrayAsync()
            End Using
        End Using
    End Function
		
    Public Async Function ConvertDocumentAsync() As Task
        Dim rapidApiKey = "<YOUR RAPIDAPI KEY HERE>"
        Dim filePathToConvert = "<FILE PATH TO CONVERT>"
        Dim taskId = Await SubmitPdfConversionTask(filePathToConvert, rapidApiKey)
        Dim retryCount = 0
        Do While (retryCount < 100)
            retryCount += 1
            Await Task.Delay(5000)
            Dim status = Await GetConversionTaskStatus(taskId, rapidApiKey)
            If (status = "Completed") Then
                Dim fileBytes = Await DownloadResult(taskId, rapidApiKey)
                Await File.WriteAllBytesAsync("final_report.pdf", fileBytes)
                Exit Do
            ElseIf (status = "Waiting") Then
                Continue Do
            ElseIf (status = "Failed") Then
                Throw New Exception("Cannot convert file")
            Else
                Throw New Exception("Invalid status")
            End If
        Loop
    End Function
		
    Sub Main(args As String())
        ConvertDocumentAsync().Wait()
    End Sub
End Module