Question

我有一个VB.NET应用程序，它生成一个我需要发布到Web应用程序的XML文档。在发布XML之前，我需要压缩XML并对其进行base64编码。下面我有一个代码片段，我在其中使用XML字符串，使用gzip压缩然后使用base64编码。为了确保我正在做的是正确的，我然后解码base64，然后gzip解压缩。解压缩后，原始XML比我测试的XML长2个字节。我正在丢弃最后2个字节。他们去哪儿了？

    Dim xml As String = ds.ToXMLString()

    ' compress and encode
    Dim ceb() As Byte = System.Text.Encoding.UTF8.GetBytes(xml)
    Dim cems As New System.IO.MemoryStream()
    Dim cegz As New System.IO.Compression.GZipStream(cems, IO.Compression.CompressionMode.Compress)
    cegz.Write(ceb, 0, ceb.Length)
    Dim cees As String = System.Convert.ToBase64String(cems.ToArray())

    ' i want to make sure everything is working,
    ' decode and decompress and make sure it matches
    Dim ddb() As Byte = System.Convert.FromBase64String(cees)
    Dim ddms As New System.IO.MemoryStream(ddb)
    Dim ddgz As New System.IO.Compression.GZipStream(ddms, IO.Compression.CompressionMode.Decompress)
    Dim ddms2 As New System.IO.MemoryStream()
    ddgz.CopyTo(ddms2)

    Dim xmlRestored As String = System.Text.Encoding.UTF8.GetString(ddms2.ToArray())

    Assert.AreEqual(xml.Substring(0, xmlRestored.Length), xmlRestored) ' <-- SUCCESS
    Assert.AreEqual(xml.Length, xmlRestored.Length) ' <-- FAILS; xml.length=147802; xmlRestored.length=147800;

Answer 1

没关系。我没有关闭我的压缩流。应该是这样的：

Dim xml As String = ds.ToXMLString()

' compress and encode
Dim ceb() As Byte = System.Text.Encoding.UTF8.GetBytes(xml)
Dim cems As New System.IO.MemoryStream()
Dim cegz As New System.IO.Compression.GZipStream(cems, IO.Compression.CompressionMode.Compress)
cegz.Write(ceb, 0, ceb.Length)

' i was missing the closing of the gzip stream
cegz.Close()

Dim cees As String = System.Convert.ToBase64String(cems.ToArray())

' i want to make sure everything is working,
' decode and decompress and make sure it matches
Dim ddb() As Byte = System.Convert.FromBase64String(cees)
Dim ddms As New System.IO.MemoryStream(ddb)
Dim ddgz As New System.IO.Compression.GZipStream(ddms, IO.Compression.CompressionMode.Decompress)
Dim ddms2 As New System.IO.MemoryStream()
ddgz.CopyTo(ddms2)

Dim xmlRestored As String = System.Text.Encoding.UTF8.GetString(ddms2.ToArray())

Assert.AreEqual(xml, xmlRestored) ' <-- SUCCESS
Assert.AreEqual(xml.Length, xmlRestored.Length) ' <-- SUCCESS

压缩和编码字符串丢弃最后两个字节

1 个答案: