Question

以下是我用于压缩和解压缩目的的代码。我的目标是将数据表转换为XML然后转换为二进制压缩格式，然后将其读回并将二进制文件转换回XML。所以，基本上，我将XML转换为二进制压缩，然后将压缩二进制转换回XML。逻辑上，数据大小应该相同，但新解压缩的XML文件由于某种原因会丢失一个字节或更多。你能帮助我吗？

Imports System
Imports System.IO
Imports System.Runtime.Serialization
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.IO.Compression
Imports System.Data.SqlClient
Imports System.Data.Sql

Public Class Form1
Dim dt As New SmExplorerDataDataSet.smedataDataTable
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

    Dim ta As New SmExplorerDataDataSetTableAdapters.smedataTableAdapter
    ta.Fill(dt)
    dt.WriteXml("abc.xml")

    'Read the XML file and compress it
    Dim in_fs As FileStream = New FileInfo("abc.xml").OpenRead
    Dim out_fs As FileStream = File.Create("def.cmp")
    in_fs.CopyTo(New DeflateStream(out_fs, CompressionMode.Compress))
    in_fs.Close()
    out_fs.Close()

    'Read the compressed file and decompress it back into XML
    in_fs = New FileStream("def.cmp", FileMode.Open, FileAccess.Read)
    out_fs = New FileStream("abc2.xml", FileMode.OpenOrCreate, FileAccess.Write)
    Dim DFS As DeflateStream = New DeflateStream(in_fs, CompressionMode.Decompress)
    DFS.CopyTo(out_fs)
    in_fs.Close()
    out_fs.Close()
End Sub
End Class

在第一个XML（原始文件）中，结束行正确地结束了documentelement标记，如新的解压缩XML文件中的 DocumentElement BUT，此标记中缺少最后几个字符，它看起来像关注 DocumentElem 当我尝试再次阅读时，这会导致错误。请帮助。

Answer 1

始终使用Using资源IDisposable来避免此类问题：

Using in_fs = File.OpenRead("abc.xml")
    Using out_fs = File.Create("def.cmp")
        Using df_fs = New DeflateStream(out_fs, CompressionMode.Compress)
            in_fs.CopyTo(df_fs)
        End Using
    End Using
End Using

Using in_fs = File.OpenRead("def.cmp")
    Using out_fs = File.Create("abc2.xml")
        Using df_fs = New DeflateStream(in_fs, CompressionMode.Decompress)
            df_fs.CopyTo(out_fs)
        End Using
    End Using
End Using

压缩方法丢失一个或多个字节VB.NET

1 个答案: