SPChangeToken constructor (String)
初始化SPChangeToken類別，其序列化表單為基礎的新執行個體。
Namespace: Microsoft.SharePoint
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Syntax
'宣告
Public Sub New ( _
strChangeToken As String _
)
'用途
Dim strChangeToken As String
Dim instance As New SPChangeToken(strChangeToken)
public SPChangeToken(
string strChangeToken
)
參數
strChangeToken
Type: System.String變更權杖序列化的形式。
Exceptions
| Exception | Condition |
|---|---|
| InvalidOperationException | strChangeToken並未包含正確的語彙基元。 -或- strChangeToken所指定的版本不是 1。 |
備註
這個建構函式的多載適合用來重新建構被序列化，然後儲存在磁碟上的變更語彙基元。如需有關序列化SPChangeToken物件的資訊，請參閱ToString方法。
序列化的語彙基元會有五個欄位，並以分號 (;)，以下列順序：
Examples
下列範例是一個主控台應用程式，查詢變更記錄的內容資料庫範圍的變更。
第一次執行應用程式，從記錄檔的開頭開始的所有變更都查詢記錄檔。這項查詢會執行第一次將SPChangeQuery物件的 [ ChangeTokenStart ] 屬性設定為 null 值，然後再將SPQuery物件傳遞至GetChanges方法。在處理所有變更之後，程式會藉由呼叫ToString()方法會序列化上次變更語彙基元，從最後的批次的變更，且將結果儲存在磁碟上的檔案。
在後續的執行，程式會還原序列化已儲存的變更語彙基元，用它來設定ChangeTokenStart屬性為其查詢與變更記錄檔]。重要的工作是在GetStartingToken函式，即稱為SPChangeToken的建構函式。
using System;
using System.IO;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Administration;
namespace Test
{
class ConsoleApp
{
private const string DATA_FILE_PATH = "ChangeToken.dat";
static void Main(string[] args)
{
using (SPSite site = new SPSite("https://localhost"))
{
SPChangeQuery query = new SPChangeQuery(true, true);
query.ChangeTokenStart = GetStartingToken();
while (true)
{
// Get a batch of changes.
SPChangeCollection changes = site.ContentDatabase.GetChanges(query);
// Process them.
foreach (SPChange change in changes)
{
Console.WriteLine("Date: {0} Type of object: {1} Type of change: {2}",
change.Time.ToShortDateString(), change.GetType().ToString(), change.ChangeType);
}
// Starting point for next batch.
query.ChangeTokenStart = changes.LastChangeToken;
// If this is the last batch, exit.
if (changes.Count < query.FetchLimit)
break;
}
// Serialize the last token as a starting point for the next run.
SaveLastToken(query.ChangeTokenStart);
}
Console.Write("\nPress ENTER to continue...");
Console.ReadLine();
}
static SPChangeToken GetStartingToken()
{
// Passing a null token to GetChanges fetches
// changes from the start of the log.
SPChangeToken token = null;
// If we have a token from the last run, use it.
if (File.Exists(DATA_FILE_PATH))
{
using (FileStream fs = File.OpenRead(DATA_FILE_PATH))
{
BinaryReader br = new BinaryReader(fs);
try
{
string str = br.ReadString();
// Construct a change token from serialized string.
token = new SPChangeToken(str);
}
catch (EndOfStreamException e)
{
// No serialized string, so do nothing.
}
finally
{
br.Close();
}
}
}
return token;
}
static void SaveLastToken(SPChangeToken token)
{
using (FileStream fs = File.Create(DATA_FILE_PATH))
{
// Serialize the token.
BinaryWriter bw = new BinaryWriter(fs);
string s = token.ToString();
bw.Write(s);
// Flush and close.
bw.Flush();
bw.Close();
}
}
}
}
Imports System
Imports System.IO
Imports Microsoft.SharePoint
Imports Microsoft.SharePoint.Administration
Module ConsoleApp
Private Const DATA_FILE_PATH As String = "ChangeToken.dat"
Sub Main()
Using site As SPSite = New SPSite("https://localhost")
Dim query As New SPChangeQuery(True, True)
query.ChangeTokenStart = GetStartingToken()
While (True)
' Get a batch of changes.
Dim changes As SPChangeCollection = site.ContentDatabase.GetChanges(query)
' Process them.
For Each change As SPChange In changes
Console.WriteLine("Date: {0} Type of object: {1} Type of change: {2}", _
change.Time.ToShortDateString(), change.GetType().ToString(), change.ChangeType)
Next
' This is the starting point for next batch.
query.ChangeTokenStart = changes.LastChangeToken
' If this is the last batch, exit.
If changes.Count < query.FetchLimit Then
Exit While
End If
End While
' Serialize the last token as a starting point for the next run.
SaveLastToken(query.ChangeTokenStart)
End Using
Console.Write(vbCrLf + "Press ENTER to continue...")
Console.ReadLine()
End Sub
Function GetStartingToken() As SPChangeToken
' Passing a null token to GetChanges fetches
' changes from the start of the log.
Dim token As SPChangeToken = Nothing
' If we have a token from the last run, use it.
If File.Exists(DATA_FILE_PATH) Then
Using fs As FileStream = File.OpenRead(DATA_FILE_PATH)
Dim br As BinaryReader = New BinaryReader(fs)
Try
Dim str As String = br.ReadString()
' Construct a change token from serialized string.
token = New SPChangeToken(str)
Catch e As EndOfStreamException
' No serialized string, so do nothing.
Finally
br.Close()
End Try
End Using
End If
Return token
End Function
Sub SaveLastToken(ByRef token As SPChangeToken)
Using fs As FileStream = File.Create(DATA_FILE_PATH)
' Serialize the token.
Dim bw As BinaryWriter = New BinaryWriter(fs)
Dim s As String = token.ToString()
bw.Write(s)
' Flush and close.
bw.Flush()
bw.Close()
End Using
End Sub
End Module