遍历所有session并取值

Posted on 2004-12-28 11:45 squirrel_sc 阅读(3739) 评论(5) 编辑收藏

首先要说明的是，该方法仅对将session存放于sql server中有效。很多人说session存放于sql server中效率太低，我觉得这只能说低一些，不能说太低。这其中的好处更大一些，如果将session存放在进程内，应用程序一重启就没了，有时候很麻烦；存放在进程外和存放在数据库中效率几乎一样。

这个类是从.net framework的源码里得到的，删除了updatesession的部分，只保留了获得session的部分，可以单独作为一个类或者放在类中做私有类使用。

#Region "分析Session的私有类"

Private Class altSerialization

' Methods

Shared Sub New()

Dim typeArray1 As Type() = New Type(21) {}

typeArray1(1) = GetType(String)

typeArray1(2) = GetType(Integer)

typeArray1(3) = GetType(Boolean)

typeArray1(4) = GetType(DateTime)

typeArray1(5) = GetType(Decimal)

typeArray1(6) = GetType(Byte)

typeArray1(7) = GetType(Char)

typeArray1(8) = GetType(Single)

typeArray1(9) = GetType(Double)

typeArray1(10) = GetType(SByte)

typeArray1(11) = GetType(Short)

typeArray1(12) = GetType(Long)

typeArray1(13) = GetType(UInt16)

typeArray1(14) = GetType(UInt32)

typeArray1(15) = GetType(UInt64)

typeArray1(16) = GetType(TimeSpan)

typeArray1(17) = GetType(Guid)

typeArray1(18) = GetType(IntPtr)

typeArray1(19) = GetType(UIntPtr)

altSerialization.s_serializedTypes = typeArray1

End Sub

Private Sub New()

End Sub

Public Shared Function ReadValueFromStream(ByVal reader As BinaryReader) As Object

Dim numArray1 As Integer()

Dim num1 As Integer

Dim buffer1 As Byte()

Dim formatter1 As System.Runtime.Serialization.Formatters.Binary.BinaryFormatter

Dim obj1 As Object = Nothing

Select Case CType(reader.ReadByte, TypeID)

Case CType(CType(CType(1, TypeID), TypeID), TypeID)

Return reader.ReadString

Case CType(CType(CType(2, TypeID), TypeID), TypeID)

Return reader.ReadInt32

Case CType(CType(CType(3, TypeID), TypeID), TypeID)

Return reader.ReadBoolean

Case CType(CType(CType(4, TypeID), TypeID), TypeID)

Return New DateTime(reader.ReadInt64)

Case CType(CType(CType(5, TypeID), TypeID), TypeID)

numArray1 = New Integer(4) {}

num1 = 0

GoTo Label_00CA

Case CType(CType(CType(6, TypeID), TypeID), TypeID)

Return reader.ReadByte

Case CType(CType(CType(7, TypeID), TypeID), TypeID)

Return reader.ReadChar

Case CType(CType(CType(8, TypeID), TypeID), TypeID)

Return reader.ReadSingle

Case CType(CType(CType(9, TypeID), TypeID), TypeID)

Return reader.ReadDouble

Case CType(CType(CType(10, TypeID), TypeID), TypeID)

Return reader.ReadSByte

Case CType(CType(CType(11, TypeID), TypeID), TypeID)

Return reader.ReadInt16

Case CType(CType(CType(12, TypeID), TypeID), TypeID)

Return reader.ReadInt64

Case CType(CType(CType(13, TypeID), TypeID), TypeID)

Return reader.ReadUInt16

Case CType(CType(CType(14, TypeID), TypeID), TypeID)

Return reader.ReadUInt32

Case CType(CType(CType(15, TypeID), TypeID), TypeID)

Return reader.ReadUInt64

Case CType(CType(CType(16, TypeID), TypeID), TypeID)

Return New TimeSpan(reader.ReadInt64)

Case CType(CType(CType(17, TypeID), TypeID), TypeID)

buffer1 = reader.ReadBytes(16)

Return New Guid(buffer1)

Case CType(CType(CType(18, TypeID), TypeID), TypeID)

If (IntPtr.Size = 4) Then

Return New IntPtr(reader.ReadInt32)

End If

GoTo Label_01D3

Case CType(CType(CType(19, TypeID), TypeID), TypeID)

If (UIntPtr.Size = 4) Then

Return New UIntPtr(reader.ReadUInt32)

End If

GoTo Label_0201

Case CType(CType(CType(20, TypeID), TypeID), TypeID)

formatter1 = New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter

Return formatter1.Deserialize(reader.BaseStream)

Case CType(CType(CType(21, TypeID), TypeID), TypeID)

GoTo Label_022B

End Select

Return obj1

Label_00BD:

numArray1(num1) = reader.ReadInt32

num1 = (num1 + 1)

Label_00CA:

If (num1 < 4) Then

GoTo Label_00BD

End If

Return New Decimal(numArray1)

Label_01D3:

Return New IntPtr(reader.ReadInt64)

Label_0201:

Return New UIntPtr(reader.ReadUInt64)

Label_022B:

Return Nothing

End Function

' Fields

Private Shared s_serializedTypes As Type()

' Nested Types

Private Enum TypeID

' Fields

[Boolean] = 3

[Byte] = 6

[Char] = 7

DateTime = 4

[Decimal] = 5

[Double] = 9

Guid = 17

Int16 = 11

Int32 = 2

Int64 = 12

IntPtr = 18

[Null] = 21

[Object] = 20

SByte = 10

[Single] = 8

[String] = 1

TimeSpan = 16

UInt16 = 13

UInt32 = 14

UInt64 = 15

UIntPtr = 19

End Enum

End Class

#End Region

使用它的核心代码（.net framework对我抛弃的几个bool以及数值进行了一些判断，我没有深究，有朋友研究过的请指点一下。）

Dim sql As String = "select * from ASPState..ASPStateTempSessions where datediff(minute, LockDateLocal, GetDate()) < 20"

Dim dt As New DataTable

DataDriver.GetRows(sql, dt) '该方法用于从数据库中获取一个数据集，可参考我的文章：http://www.cnblogs.com/squirrel_sc/archive/2004/11/04/60447.html

Dim sTemp As String

Dim obj As Object

Dim st As New MemoryStream

Dim str As New BinaryReader(st)

Dim col As New System.Collections.Specialized.NameValueCollection

For i As Integer = 0 To dt.Rows.Count - 1

Dim bTemp() As Byte = dt.Rows(i)("SessionItemShort")

st.SetLength(0)

st.Write(bTemp, 0, bTemp.Length)

st.Seek(0, SeekOrigin.Begin)

str.ReadInt32()

str.ReadBoolean()

Dim iCount As Integer = str.ReadInt32

Dim btTemp As Byte

str.ReadInt32()

For k As Integer = 0 To iCount - 1

sTemp = str.ReadString

obj = altSerialization.ReadValueFromStream(str)

'obj就是sTemp这个session名字对应的内容，它的类型不定。在这里对其进行操作就可以了

str.Close()

st.Close()

使用实例：
该方法用于遍历所有session，形成在线用户列表。由于这个操作可能效率较低，所以把结果在内存中缓存1分钟。用户名存在名为UserName的session中。

Private Shared _onlineUserList As ArrayList

Private Shared _onlineUserUpdateTime As DateTime

Public Shared Function GetOnlineUserList() As ArrayList

If (_onlineUserList Is Nothing) Then

_onlineUserList = New ArrayList

_onlineUserUpdateTime = Now

End If

If (_onlineUserUpdateTime.AddMinutes(1) < Now OrElse _onlineUserList.Count = 0) Then

_onlineUserList.Clear()

Dim sql As String = "select * from ASPState..ASPStateTempSessions where datediff(minute, LockDateLocal, GetDate()) < 20"

Dim dt As New DataTable

DataDriver.GetRows(sql, dt)

Dim sTemp As String

Dim obj As Object

Dim st As New MemoryStream

Dim str As New BinaryReader(st)

Dim col As New System.Collections.Specialized.NameValueCollection

For i As Integer = 0 To dt.Rows.Count - 1

Dim bTemp() As Byte = dt.Rows(i)("SessionItemShort")

st.SetLength(0)

st.Write(bTemp, 0, bTemp.Length)

st.Seek(0, SeekOrigin.Begin)

str.ReadInt32()

str.ReadBoolean()

Dim iCount As Integer = str.ReadInt32

Dim btTemp As Byte

str.ReadInt32()

For k As Integer = 0 To iCount - 1

sTemp = str.ReadString

obj = altSerialization.ReadValueFromStream(str)

If (sTemp = "UserName" AndAlso _onlineUserList.BinarySearch(obj) < 0) Then

_onlineUserList.Add(DirectCast(obj, String))

Exit For

End If

str.Close()

st.Close()

_onlineUserUpdateTime = Now

End If

Return _onlineUserList

End Function

关于设置：
我使用的是信任连接，在XP下就是aspnet用户，ASPState数据库就是它的，所以访问数据库的权限上没有问题。session存放在sql server中要使用持久的那种，如果是存放在tempDb中的，一重启机器后，权限就要重新设置，很苦恼。

Feedback

#1楼  　回复　 引用　 查看　

2004-12-28 13:55 by onekey

我的Session保存的是对象：

Customer customer = new Customer();
customer.name = name;

Session["Customer"] = customer;

可不可以也用sql server存放？

#2楼 [楼主] 　回复　 引用　 查看　

2004-12-28 14:19 by squirrel_sc

可以试试。可能需要你的对象支持序列化。

另外，大对象不一定会存放在SessionItemShort这个字段里，后面还有一个binary的SessionItemLong，可能会存放在这里面，不过这样的话，效率可能会很低了。

#3楼  　回复　 引用　

2006-05-05 09:25 by angelo[未注册用户]

Do you have a sample of page using the session data?

#4楼 [楼主] 　回复　 引用　 查看　

2006-05-08 17:27 by squirrel_sc

直接调用GetOnlineUserList就可以了

在.net 2.0里面，有了一个新的类System.Web.SessionState.SessionStateItemCollection，这样操作起来就简单多了。

Public Shared Function GetOnlineUserList() As ArrayList

SyncLock _onlineUserList

If (CacheManager.CanUpdate("OnlineUserList") OrElse _onlineUserList.Count = 0) Then

_onlineUserList.Clear()

Dim sql As String = "select * from ASPState..ASPStateTempSessions(NOLOCK) where datediff(minute, LockDateLocal, GetDate()) < 20 order by Created Desc"

Dim dt As New DataTable

DataDriver.GetRows(sql, dt)

Dim st As New MemoryStream

Dim str As New BinaryReader(st)

Dim ssc As System.Web.SessionState.SessionStateItemCollection

Dim b1 As Boolean

_onlineCount = dt.Rows.Count

For i As Integer = 0 To dt.Rows.Count - 1

Try

Dim bTemp() As Byte = dt.Rows(i)("SessionItemShort")

st.SetLength(0)

st.Write(bTemp, 0, bTemp.Length)

st.Seek(0, SeekOrigin.Begin)

str.ReadInt32()

b1 = str.ReadBoolean()

str.ReadBoolean()

If (b1) Then

ssc = System.Web.SessionState.SessionStateItemCollection.Deserialize(str)

If ((Not ssc("UserName") Is Nothing) AndAlso _

ssc("UserName").ToString().Length > 0 AndAlso _

_onlineUserList.BinarySearch(ssc("UserName")) < 0) Then

_onlineUserList.Add(ssc("UserName"))

End If

Catch ex As Exception

Dim value As String

Dim btInput() As Byte

Dim stEx As New MemoryStream()

Dim swEx As New StreamWriter(stEx)

Dim srEx As New StreamReader(stEx)

If (Not dt.Rows(i)("SessionItemShort") Is DBNull.Value) Then

btInput = CType(dt.Rows(i)("SessionItemShort"), Byte())

For j As Integer = 0 To btInput.Length - 1

swEx.Write("{0:X2}", btInput(j))

swEx.Flush()

stEx.Seek(0, SeekOrigin.Begin)

value = srEx.ReadToEnd()

UtilTools.SaveDebugInfo("这个session有问题：" & value & vbCrLf & ex.ToString(), True)

End If

End Try

str.Close()

st.Close()

End If

End SyncLock

Return _onlineUserList

End Function

#5楼  　回复　 引用　

2008-06-24 11:08 by 士大夫[未注册用户]

CacheManager.CanUpdate("OnlineUserList") 看不懂是什么意思

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