背景

微軟的日志庫一般是輸出到控制臺的，但是在WPF中并不能直接使用控制臺，需要AllocConsole。
但是這種做法個(gè)人覺得不太安全(一關(guān)閉控制臺整個(gè)程序就退出了?)。這時(shí)候就需要一個(gè)更加友好的方式輸出日志。

問題

那如何將日志的內(nèi)容顯示到RichTextBox中?

實(shí)現(xiàn)LoggerProcessor

• 這里參照官方的ConsoleLoggerProcessor，但是需要有點(diǎn)區(qū)別。

public class RichTextBoxLoggerProcessor:IDisposable
{
    ///...其他實(shí)現(xiàn)請參照Microsoft.Extension.Logging的源碼
    private readonly RichTextBoxDocumentStorage _storage;
    private readonly Thread _outputThread;

    /// 這個(gè)構(gòu)造函數(shù)傳入RichTextBoxDocumentStorage，用于顯示單條日志記錄
    public RichTextBoxLoggerProcessor(RichTextBoxDocumentStorage storage,       LoggerQueueFullMode fullMode, int maxQueueLength)
    {
        _storage = storage;
        _messageQueue = new();
        FullMode = fullMode;
        MaxQueueLength = maxQueueLength;
        _outputThread = new Thread(ProcessMessageQueue)
        {
            IsBackground = true,
            Name = "RichTextBox logger queue processing thread"
        };
        _outputThread.Start();
    }

    ///改寫WriteMessage方法，熟悉FlowDocument的兄弟應(yīng)該都知道Paragraph是什么吧
    public void WriteMessage(Paragraph message)
    {
        try
        {
            //發(fā)送回FlowDocument所在的線程后添加Paragraph
            _storage.Document?.Dispatcher.BeginInvoke(() =>
            {
                _storage.Document.Blocks.Add(message);
            });
        }
        catch
        {
            CompleteAdding();
        }
    }

    //同理改寫EnqueMessage方法和Enqueue等方法
    public void EnqueMessage(Paragraph message)
    {
        //...具體邏輯請參閱github源碼
    }

    public bool Enqueue(Paragraph message)
    {
        //...
    }

     public bool TryDequeue(out Paragraph entry)
     {
        //...
     }
}

public class RichTextBoxDocumentStorage
{
    ///因?yàn)橐褂玫紻I，所以創(chuàng)建一個(gè)類來存放FlowDocument;
    public FlowDocument? Document{ get; set; }
}

實(shí)現(xiàn)RichTextBoxLogger

• 這里繼承ILogger接口

public class RichTextBoxLogger:ILogger
{
    private string _category;
    private RichTextBoxLoggerProcessor _processor;

    public RichTextBoxLogger(string category, RichTextBoxLoggerProcessor processor, RichTextBoxFormatter formatter)
    {
        _category = category;
        _processor = processor;
        Formatter = formatter;
    }

    //LogEntry格式化器
    public RichTextBoxFormatter Formatter { get; set; }

    public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
    {
        var logEntry = new LogEntry<TState>(logLevel, _category, eventId, state, exception, formatter);

        //paragraph 需要在主線程創(chuàng)建
        App.Current.Dispatcher.BeginInvoke(() =>
        {
            var message = Formatter.Write(in logEntry);
            if (message is null)
            {
              return;
            }
            _processor.EnqueMessage(message);
      });
  }
}

public abstract class RichTextBoxFormatter
{
    protected RichTextBoxFormatter(string name)
    {
        Name = name;
    }

    public string Name { get; }

    public abstract Paragraph? Write<TState>(in LogEntry<TState> logEntry);
}

創(chuàng)建LoggerProvider

public class RichTextBoxLoggerProvider: ILoggerProvider
{
    private readonly RichTextBoxFormatter _formatter;
    private readonly ConcurrentDictionary<string,RichTextBoxLogger> _loggers = [];
    private readonly RichTextBoxLoggerProcessor _processor;
    public RichTextBoxLoggerProvider(RichTextBoxDocumentStorage storage, RichTextBoxFormatter formatter)
    {
        _formatter = formatter;
        _processor = new RichTextBoxLoggerProcessor(storage, LoggerQueueFullMode.Wait, 2500);
        _formatter = formatter;
    }

    public ILogger CreateLogger(string categoryName)
    {
        return _loggers.GetOrAdd(categoryName, new RichTextBoxLogger(categoryName, _processor, _formatter));
    }
}

創(chuàng)建真正的LogViewer

• 這里使用的是Window來展現(xiàn)日志

public class LogViewer : Window
{
    public LogViewer(RichTextBoxDocumentStorage storage)
    {
        InitializeComponent();
        if(storage.Document is null)
        {
            //確保FlowDocument是在主線程上創(chuàng)建的
            App.Current.Dispatcher.Invoke(()=>{
                _storage.Document =  new FlowDocument() { TextAlignment = System.Windows.TextAlignment.Left }; 
            });
        }
        logPresenter.Document = storage.Document;
    }
}

注冊服務(wù)

public static class RichTextBoxLoggingExtension 
{
    public static ILoggingBuilder AddRichTextBoxLogger(this ILoggingBuilder builder)
    {
        builder.Services.AddSingleton<RichTextBoxDocumentStorage>();
        //格式化的實(shí)現(xiàn)就不寫了，按自己的喜好來寫寫格式化器；這里是參照的SimpleConsoleFormatter實(shí)現(xiàn)的
        builder.Services.AddSingleton<RichTextBoxFormatter, SimpleRichTextBoxFormatter>();
        builder.Services.AddSingleton<ILoggerProvider,RichTextBoxLoggerProvider>();
        return builder;
    }
}

具體使用

• 任意位置使用ServiceProvider喚起LogViewer即可

public class SomeClass
{
    public void OpenLogViewer()
    {
        App.Current.Services.GetRequiredService<LogViewer>().Show();
    }
}

結(jié)尾

這里只是實(shí)現(xiàn)了個(gè)簡單的輸出，還有好多好多功能沒有實(shí)現(xiàn)。
不喜歡寫太長的解釋說明，感覺好麻煩。代碼就是最好的說明（
看哪天心血來潮了，做個(gè)nuget包吧。