我把從我的C＃代碼，與下面的頭一個方法的API如何在.NET中將單個TextWriter分成多個輸出？
public void ExternalFactory.SetOut(TextWriter outputStream)
我通常調用這個方法就像
ExternalFactory.SetOut(Console.Out)
只是使API編寫所有的信息到安慰。但是，除了寫入控制檯以外，我還希望將這些信息存儲在更加固定的位置，例如文本文件。
我的第一個猜測是我需要創建一些客戶TextWriter來分割流，並將一個發送到控制檯，一個發送到StreamWriter。這裏的正確方法是什麼？
你的第一個猜測是正確的。你可以概括它，並寫一個'發佈'的textwriter，它接受一個textwriters列表作爲構造時間參數，並將它收到的所有輸入分發給每一個textwriters。
您只需將數據副本發送到流（文本文件）和顯示器（控制檯）即可。
而不是標準的I/O設施，我使用log4net這種事情。我將log4net配置爲使用ConsoleAppender和FileAppender或RollingFileAppender同時登錄到控制檯和日誌文件。
好的是您可以設置日誌消息模板來捕獲各種有用的信息（時間，線程/進程ID，機器名稱等），除了記錄的消息。
您還可以登錄到SQL Server，事件日誌或遠程接收器。
簡單！
這裏是一個樣本的TextWriter實現的路由一切通過log4net的：
using System;
using System.IO;
using System.Text;
using log4net ;
namespace ConsoleApplication22
{
public class Log4NetTextWriter : TextWriter, IDisposable
{
private static ILog log = log4net.LogManager.GetLogger(typeof(Log4NetTextWriter)) ;
#region properties
private StringBuilder buffer { get ; set ; }
public override Encoding Encoding
{
get
{
// since this TextWrite is writing to log4net, we have no idea what the final encoding might be.
// It all depends on the log4net configuration: tthe appender or appenders that wind up handling the logged message
// determine the final encoding.
//
// Might make more sense to return Encoding.UTF8 though, just to return something.
throw new NotImplementedException() ;
}
}
#endregion properties ;
public override void Flush()
{
if (this.buffer != null && this.buffer.Length > 0)
{
this.WriteLine() ;
}
return ;
}
public override void Close()
{
base.Close();
}
protected override void Dispose(bool disposing)
{
this.Flush() ;
base.Dispose(disposing);
}
#region public constructors
public Log4NetTextWriter() : this(null)
{
return ;
}
public Log4NetTextWriter(IFormatProvider formatProvider) : base(formatProvider)
{
this.buffer = new StringBuilder() ;
}
#endregion public constructors
#region public Write() overloads
public override void Write(bool value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(char value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(char[] buffer)
{
this.buffer.Append(buffer) ;
return ;
}
public override void Write(char[] buffer , int index , int count)
{
this.buffer.Append(buffer , index , count) ;
return ;
}
public override void Write(decimal value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(double value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(float value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(int value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(long value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(object value)
{
this.buffer.Append(value) ;
return ;
}
public override void Write(string format , object arg0)
{
this.buffer.AppendFormat(this.FormatProvider , format , arg0) ;
return ;
}
public override void Write(string format , object arg0 , object arg1)
{
this.buffer.AppendFormat(this.FormatProvider , format , arg0 , arg1) ;
return ;
}
public override void Write(string format , object arg0 , object arg1 , object arg2)
{
this.buffer.AppendFormat(this.FormatProvider , format , arg0 , arg1 , arg2);
return ;
}
public override void Write(string format , params object[] arg)
{
this.buffer.AppendFormat(this.FormatProvider , format , arg) ;
return ;
}
public override void Write(string value)
{
this.buffer.Append(value);
return ;
}
public override void Write(uint value)
{
this.buffer.Append(value);
return ;
}
public override void Write(ulong value)
{
this.buffer.Append(value);
return ;
}
public override void WriteLine()
{
string logMessage = this.buffer.ToString() ;
this.buffer.Length = 0 ;
log.Info(logMessage) ;
return ;
}
#endregion public Write() overloads
#region public WriteLine() overloads
public override void WriteLine(bool value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(char value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(char[] buffer)
{
this.Write(buffer) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(char[] buffer , int index , int count)
{
this.Write(buffer , index , count) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(decimal value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(double value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(float value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(int value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(long value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(object value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(string format , object arg0)
{
this.Write(format , arg0) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(string format , object arg0 , object arg1)
{
this.Write(format , arg0 , arg1) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(string format , object arg0 , object arg1 , object arg2)
{
this.Write(format , arg0 , arg1 , arg2) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(string format , params object[] arg)
{
this.Write(format , arg) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(string value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(uint value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
public override void WriteLine(ulong value)
{
this.Write(value) ;
this.WriteLine() ;
return ;
}
#endregion public WriteLine() overloads
}
}
下面是一個示例log4net的配置文件。這一個日誌記錄到控制檯和日誌文件，並根據大小自動翻轉（它也可以基於日期/時間或每執行一次）。
<log4net>
<!-- Log to the console -->
<appender name="Console" type="log4net.Appender.ConsoleAppender">
<layout type="log4net.Layout.PatternLayout">
<!-- Pattern to output the caller's file name and line number -->
<conversionPattern value="%5level [%thread] (%file:%line) - %message%newline" />
</layout>
</appender>
<!-- Log to a log file. This particular setup should log to a static file name 'log.txt' -->
<!-- When it hits 100KB in size, it rolls, keeping up to 10 archived files. The archived -->
<!-- files are named 'log.text.1', 'log.txt.2', ... , 'log.txt.10' -->
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="log.txt" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="100KB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
</layout>
</appender>
<root>
<level value="DEBUG" />
<appender-ref ref="Console" />
<appender-ref ref="RollingFile" />
</root>
</log4net>
要配置log4net的，最簡單的方法是把一個XmlConfigurator屬性在AssemblyInfo.cs中，這樣的：
// Configure log4net using the .log4net file
[assembly: log4net.Config.XmlConfigurator(ConfigFileExtension="log4net",Watch=true)]
// This will cause log4net to look for a configuration file
// called TestApp.exe.log4net in the application base
// directory (i.e. the directory containing TestApp.exe)
// The config file will be watched for changes.
當你的程序正在運行，您可以打開或關閉日誌記錄，或改變其配置只需編輯和保存配置文件即可。 log4net監視配置文件的變化並在運行中自行重新配置。
我不是log4net的專家，但除非它允許我創建一個可傳遞給此外部庫的單個TextWriter對象，否則這對我的問題不起作用... – Nitax 2012-01-11 20:24:31
@Nitax：請參閱我的答案以上 – 2012-01-11 22:03:08
未經過編譯和首次使用測試，但可能會幫助某些人打字。討厭它已經不存在了。
/// <summary>
/// Spreads data out to multiple text writers.
/// </summary>
class TextWriterMulti : System.IO.TextWriter
{
private System.Collections.Generic.List<System.IO.TextWriter> writers = new System.Collections.Generic.List<System.IO.TextWriter>();
private System.IFormatProvider formatProvider = null;
private System.Text.Encoding encoding = null;
#region TextWriter Properties
public override System.IFormatProvider FormatProvider
{
get
{
System.IFormatProvider formatProvider = this.formatProvider;
if (formatProvider == null)
{
formatProvider = base.FormatProvider;
}
return formatProvider;
}
}
public override string NewLine
{
get { return base.NewLine; }
set
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.NewLine = value;
}
base.NewLine = value;
}
}
public override System.Text.Encoding Encoding
{
get
{
System.Text.Encoding encoding = this.encoding;
if (encoding == null)
{
encoding = System.Text.Encoding.Default;
}
return encoding;
}
}
#region TextWriter Property Setters
TextWriterMulti SetFormatProvider(System.IFormatProvider value)
{
this.formatProvider = value;
return this;
}
TextWriterMulti SetEncoding(System.Text.Encoding value)
{
this.encoding = value;
return this;
}
#endregion // TextWriter Property Setters
#endregion // TextWriter Properties
#region Construction/Destruction
public TextWriterMulti(System.Collections.Generic.IEnumerable<System.IO.TextWriter> writers)
{
this.Clear();
this.AddWriters(writers);
}
#endregion // Construction/Destruction
#region Public interface
public TextWriterMulti Clear()
{
this.writers.Clear();
return this;
}
public TextWriterMulti AddWriter(System.IO.TextWriter writer)
{
this.writers.Add(writer);
return this;
}
public TextWriterMulti AddWriters(System.Collections.Generic.IEnumerable<System.IO.TextWriter> writers)
{
this.writers.AddRange(writers);
return this;
}
#endregion // Public interface
#region TextWriter methods
public override void Close()
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Close();
}
base.Close();
}
protected override void Dispose(bool disposing)
{
foreach (System.IO.TextWriter writer in this.writers)
{
if (disposing)
{
writer.Dispose();
}
}
base.Dispose(disposing);
}
public override void Flush()
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Flush();
}
base.Flush();
}
//foreach (System.IO.TextWriter writer in this.writers)
//{
// writer;
//}
public override void Write(bool value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(char value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(char[] buffer)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(buffer);
}
}
public override void Write(decimal value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(double value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(float value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(int value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(long value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(object value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(string value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(uint value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(ulong value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(value);
}
}
public override void Write(string format, object arg0)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(format, arg0);
}
}
public override void Write(string format, params object[] arg)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(format, arg);
}
}
public override void Write(char[] buffer, int index, int count)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(buffer, index, count);
}
}
public override void Write(string format, object arg0, object arg1)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(format, arg0, arg1);
}
}
public override void Write(string format, object arg0, object arg1, object arg2)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.Write(format, arg0, arg1, arg2);
}
}
public override void WriteLine()
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine();
}
}
public override void WriteLine(bool value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(char value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(char[] buffer)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(buffer);
}
}
public override void WriteLine(decimal value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(double value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(float value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(int value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(long value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(object value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(string value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(uint value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(ulong value)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(value);
}
}
public override void WriteLine(string format, object arg0)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(format, arg0);
}
}
public override void WriteLine(string format, params object[] arg)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(format, arg);
}
}
public override void WriteLine(char[] buffer, int index, int count)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(buffer, index, count);
}
}
public override void WriteLine(string format, object arg0, object arg1)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(format, arg0, arg1);
}
}
public override void WriteLine(string format, object arg0, object arg1, object arg2)
{
foreach (System.IO.TextWriter writer in this.writers)
{
writer.WriteLine(format, arg0, arg1, arg2);
}
}
#endregion // TextWriter methods
}
好吧，用這種方法，我假設我的DistributingTextWriter會持有對控制檯TextWriter和StreamWriter的引用。那麼我是否必須重寫每個Write和WriteLine方法以將這些調用「分配」給所有TextWriters？ – Nitax 2012-01-11 18:52:34
恐怕是這樣的：如果你想保持與TextWriter類的接口的兼容性，你將不得不重新實現所有這些方法。但是，您可以從System.IO.StreamWriter的實現中複製大部分代碼。谷歌的「SSCLI」和/或「轉子」來找到它。 – 2012-01-11 19:03:36