Question

我正在尝试使用第三方库（一个演示，因此我无法获得支持），它提供了将HTML转换为RTf等的类，问题是我正在使用的方法需要{ {1}}存储RTF转换，但我无法正确设置，我的流仍为空。

我认为我遗漏了一些关于Stream的使用情况，因为我从不需要使用Stream，所以我真的不知道我是否正确使用了Stream对象。

我做错了什么？

System.Io.Stream

Answer 1

您正在将所有内容推送到空流（Stream.Null）;它的作用是扔掉所有东西。那是所有它。

请尝试使用新的MemoryStream，同时确保在放入数据之后以及在阅读之前将其回放（将Position设置为0）。

来自Stream.Null上的MSDN：

使用Null将输出重定向到不会消耗任何操作系统资源的流。当在Stream上调用提供写入的Null方法时，调用只会返回，并且不会写入任何数据。 Null还实现了Read方法，该方法在不读取数据的情况下返回零。

Answer 2

由于@Marc Gravell解决方案，我想分享一个我写过的帮助类。

#Region " Imports "

Imports Nasosoft.Documents.Transform
Imports System.IO
Imports System.Text

#End Region

''' <summary>
''' Performs document conversion operations.
''' </summary>
Public Class DocumentConverter

#Region " Public Methods "

    ''' <summary>
    ''' Converts RTF text to HTML.
    ''' </summary>
    ''' <param name="RtfText">Indicates the RTF text.</param>
    ''' <returns>System.String.</returns>
    Public Shared Function Rtf2Html(ByVal RtfText As String,
                                    Optional ByVal TextEncoding As Encoding = Nothing) As String

        TextEncoding = If(TextEncoding Is Nothing, Encoding.Default, TextEncoding)

        Dim RtfStream As New MemoryStream(TextEncoding.GetBytes(RtfText))
        Dim HtmlStream As New MemoryStream
        Dim HtmlText As String = String.Empty

        Using Converter As New RtfToHtmlTransform()
            Converter.Load(RtfStream)
            Converter.Transform(HtmlStream)
        End Using

        HtmlStream.Position = 0

        Using StrReader As New StreamReader(HtmlStream)
            HtmlText = StrReader.ReadToEnd
        End Using

        RtfStream.Close()
        HtmlStream.Close()

        Return HtmlText

    End Function

    ''' <summary>
    ''' Converts RTF text to TXT (Plain text).
    ''' </summary>
    ''' <param name="RtfText">Indicates the RTF text.</param>
    ''' <returns>System.String.</returns>
    Public Shared Function Rtf2Txt(ByVal RtfText As String,
                                    Optional ByVal TextEncoding As Encoding = Nothing) As String

        TextEncoding = If(TextEncoding Is Nothing, Encoding.Default, TextEncoding)

        Dim RtfStream As New MemoryStream(TextEncoding.GetBytes(RtfText))
        Dim TextStream As New MemoryStream
        Dim PlainText As String = String.Empty

        Using Converter As New RtfToTextTransform()
            Converter.Load(RtfStream)
            Converter.Transform(TextStream)
        End Using

        TextStream.Position = 0

        Using StrReader As New StreamReader(TextStream)
            PlainText = StrReader.ReadToEnd
        End Using

        RtfStream.Close()
        TextStream.Close()

        Return PlainText

    End Function

    ''' <summary>
    ''' Converts HTML text to RTF.
    ''' </summary>
    ''' <param name="HtmlText">Indicates the HTML text.</param>
    ''' <returns>System.String.</returns>
    Public Shared Function Html2Rtf(ByVal HtmlText As String,
                                    Optional ByVal TextEncoding As Encoding = Nothing) As String

        TextEncoding = If(TextEncoding Is Nothing, Encoding.Default, TextEncoding)

        Dim HtmlStream As New MemoryStream(TextEncoding.GetBytes(HtmlText))
        Dim RtfStream As New MemoryStream
        Dim RtfText As String = String.Empty

        Using Converter As New HtmlToRtfTransform()
            Converter.Load(HtmlStream)
            Converter.Transform(RtfStream)
        End Using

        RtfStream.Position = 0

        Using StrReader As New StreamReader(RtfStream)
            RtfText = StrReader.ReadToEnd
        End Using

        HtmlStream.Close()
        RtfStream.Close()

        Return RtfText

    End Function

    ''' <summary>
    ''' Converts HTML text to TXT (Plain text).
    ''' </summary>
    ''' <param name="HtmlText">Indicates the HTML text.</param>
    ''' <returns>System.String.</returns>
    Public Shared Function HtmlTxt(ByVal HtmlText As String,
                                   Optional ByVal TextEncoding As Encoding = Nothing) As String

        TextEncoding = If(TextEncoding Is Nothing, Encoding.Default, TextEncoding)

        Dim HtmlStream As New MemoryStream(TextEncoding.GetBytes(HtmlText))
        Dim TextStream As New MemoryStream
        Dim PlainText As String = String.Empty

        Using Converter As New HtmlToTextTransform()
            Converter.Load(HtmlStream)
            Converter.Transform(TextStream)
        End Using

        TextStream.Position = 0

        Using StrReader As New StreamReader(TextStream)
            PlainText = StrReader.ReadToEnd
        End Using

        HtmlStream.Close()
        TextStream.Close()

        Return PlainText

    End Function

#End Region

End Class

处理流的简单问题

2 个答案: