背景
微软的日志库一般是输出到控制台的，但是在WPF中并不能直接使用控制台，需要AllocConsole。
但是这种做法个人觉得不太安全(一关闭控制台整个程序就退出了?)。这时候就需要一个更加友好的方式输出日志。
问题
那如何将日志的内容显示到RichTextBox中?
实现LoggerProcessor
- 这里参照官方的ConsoleLoggerProcessor，但是需要有点区别。
public class RichTextBoxLoggerProcessor:IDisposable
{///...其他实现请参照Microsoft.Extension.Logging的源码private readonly RichTextBoxDocumentStorage _storage;private readonly Thread _outputThread;/// 这个构造函数传入RichTextBoxDocumentStorage，用于显示单条日志记录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();}///改写WriteMessage方法，熟悉FlowDocument的兄弟应该都知道Paragraph是什么吧public void WriteMessage(Paragraph message){try{//发送回FlowDocument所在的线程后添加Paragraph_storage.Document?.Dispatcher.BeginInvoke(() =>{_storage.Document.Blocks.Add(message);});}catch{CompleteAdding();}}//同理改写EnqueMessage方法和Enqueue等方法public void EnqueMessage(Paragraph message){//...具体逻辑请参阅github源码}public bool Enqueue(Paragraph message){//...}public bool TryDequeue(out Paragraph entry){//...}
}public class RichTextBoxDocumentStorage
{///因为要使用到DI，所以创建一个类来存放FlowDocument;public FlowDocument? Document{ get; set; }
}
实现RichTextBoxLogger
- 这里继承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 需要在主线程创建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);
}
创建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));}
}
创建真正的LogViewer
- 这里使用的是Window来展现日志
public class LogViewer : Window
{public LogViewer(RichTextBoxDocumentStorage storage){InitializeComponent();if(storage.Document is null){//确保FlowDocument是在主线程上创建的App.Current.Dispatcher.Invoke(()=>{_storage.Document = new FlowDocument() { TextAlignment = System.Windows.TextAlignment.Left }; });}logPresenter.Document = storage.Document;}
}
注册服务
public static class RichTextBoxLoggingExtension
{public static ILoggingBuilder AddRichTextBoxLogger(this ILoggingBuilder builder){builder.Services.AddSingleton<RichTextBoxDocumentStorage>();//格式化的实现就不写了，按自己的喜好来写写格式化器；这里是参照的SimpleConsoleFormatter实现的builder.Services.AddSingleton<RichTextBoxFormatter, SimpleRichTextBoxFormatter>();builder.Services.AddSingleton<ILoggerProvider,RichTextBoxLoggerProvider>();return builder;}
}
具体使用
- 任意位置使用ServiceProvider唤起LogViewer即可
public class SomeClass
{public void OpenLogViewer(){App.Current.Services.GetRequiredService<LogViewer>().Show();}
}
结尾
这里只是实现了个简单的输出，还有好多好多功能没有实现。
不喜欢写太长的解释说明，感觉好麻烦。代码就是最好的说明（
看哪天心血来潮了，做个nuget包吧。
