主控台記錄格式

發行項
04/11/2024

在 .NET 5 中，Microsoft.Extensions.Logging.Console 命名空間中的主控台記錄已新增自訂格式的支援。有三個預先定義的可用格式選項：Simple、Systemd 和 Json。

重要

先前可供列舉 ConsoleLoggerFormat，以便選取所需的記錄格式：可為人類可閱讀的 Default，或為單一行 Systemd。但這些格式無法自訂，且現在已淘汰。

在本文中，您將了解主控台記錄格式器。範例原始程式碼將示範如何：

登錄新的格式器
選取要使用的已登錄格式器
- 透過程式碼或組態
實作自訂格式器
- 透過 IOptionsMonitor<TOptions> 更新組態
- 啟用自訂色彩格式

提示

所有記錄範例原始程式碼都可在範例瀏覽器中下載。如需詳細資訊，請參閱瀏覽程式碼範例: 在 .NET 中記錄。

登錄格式器

Console 記錄提供者有數個預先定義的格式器，且公開自行撰寫自訂格式器的功能。若要登錄任何可用的格式器，請使用對應的 Add{Type}Console 擴充方法：

可用類型	登錄類型的方法
ConsoleFormatterNames.Json	ConsoleLoggerExtensions.AddJsonConsole
ConsoleFormatterNames.Simple	ConsoleLoggerExtensions.AddSimpleConsole
ConsoleFormatterNames.Systemd	ConsoleLoggerExtensions.AddSystemdConsole

簡單

若要使用 Simple 主控台格式器，請使用 AddSimpleConsole 登錄：

using Microsoft.Extensions.Logging;

using ILoggerFactory loggerFactory =
    LoggerFactory.Create(builder =>
        builder.AddSimpleConsole(options =>
        {
            options.IncludeScopes = true;
            options.SingleLine = true;
            options.TimestampFormat = "HH:mm:ss ";
        }));

ILogger<Program> logger = loggerFactory.CreateLogger<Program>();
using (logger.BeginScope("[scope is enabled]"))
{
    logger.LogInformation("Hello World!");
    logger.LogInformation("Logs contain timestamp and log level.");
    logger.LogInformation("Each log message is fit in a single line.");
}

在上述範例原始程式碼中，已登錄 ConsoleFormatterNames.Simple 格式器。其中提供記錄功能，不僅可包裝各記錄訊息中的時間和記錄層級等資訊，也允許訊息的 ANSI 色彩內嵌和縮排。

當此範例應用程式執行時，將會顯示下列格式的記錄訊息：

Systemd

ConsoleFormatterNames.Systemd 主控台記錄器：

使用「Syslog」記錄層級格式和嚴重性
不會使用色彩格式化訊息
一律以單行記錄訊息

這通常適用於使用 Systemd 主控台記錄的容器。使用 .NET 5 時，Simple 主控台記錄器也會啟用精簡版本、以單行記錄，同時允許停用先前範例所顯示的色彩。

using Microsoft.Extensions.Logging;

using ILoggerFactory loggerFactory =
    LoggerFactory.Create(builder =>
        builder.AddSystemdConsole(options =>
        {
            options.IncludeScopes = true;
            options.TimestampFormat = "HH:mm:ss ";
        }));

ILogger<Program> logger = loggerFactory.CreateLogger<Program>();
using (logger.BeginScope("[scope is enabled]"))
{
    logger.LogInformation("Hello World!");
    logger.LogInformation("Logs contain timestamp and log level.");
    logger.LogInformation("Systemd console logs never provide color options.");
    logger.LogInformation("Systemd console logs always appear in a single line.");
}

此範例會產生與下列類似記錄訊息的輸出：

Json

若要以 JSON 格式寫入記錄，則會使用 Json 主控台格式器。範例原始程式碼示範 ASP.NET Core 應用程式將其登錄的方式。使用 webapp 範本，使用 dotnet new 命令建立新的 ASP.NET Core 應用程式：

dotnet new webapp -o Console.ExampleFormatters.Json

執行應用程式時，使用範本程式碼，您會取得下列預設記錄格式：

info: Console.ExampleFormatters.Json.Startup[0]
      Hello .NET friends!
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: https://localhost:5001
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: .\snippets\logging\console-formatter-json

Simple 主控台記錄格式器預設會選取預設組態。您可在 AddJsonConsoleProgram.cs 中呼叫進行變更：

using System.Text.Json;

HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);

builder.Logging.AddJsonConsole(options =>
{
    options.IncludeScopes = false;
    options.TimestampFormat = "HH:mm:ss ";
    options.JsonWriterOptions = new JsonWriterOptions
    {
        Indented = true
    };
});

using IHost host = builder.Build();

var logger =
    host.Services
        .GetRequiredService<ILoggerFactory>()
        .CreateLogger<Program>();

logger.LogInformation("Hello .NET friends!");

await host.RunAsync();

或者，您也可使用記錄組態 (例如 appsettings.json 檔案中的組態) 來進行設定：

{
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft": "Warning",
            "Microsoft.Hosting.Lifetime": "Information"
        },
        "Console": {
            "LogLevel": {
                "Default": "Information",
                "Microsoft": "Warning",
                "Microsoft.Hosting.Lifetime": "Information"
            },
            "FormatterName": "json",
            "FormatterOptions": {
                "SingleLine": true,
                "IncludeScopes": true,
                "TimestampFormat": "HH:mm:ss ",
                "UseUtcTimestamp": true,
                "JsonWriterOptions": {
                    "Indented": true
                }
            }
        }
    },
    "AllowedHosts": "*"
}

再次執行應用程式，在進行上述變更後，記錄訊息現在會格式化為 JSON：

{
  "Timestamp": "02:28:19 ",
  "EventId": 0,
  "LogLevel": "Information",
  "Category": "Console.ExampleFormatters.Json.Startup",
  "Message": "Hello .NET friends!",
  "State": {
    "Message": "Hello .NET friends!",
    "{OriginalFormat}": "Hello .NET friends!"
  }
}
{
  "Timestamp": "02:28:21 ",
  "EventId": 14,
  "LogLevel": "Information",
  "Category": "Microsoft.Hosting.Lifetime",
  "Message": "Now listening on: https://localhost:5001",
  "State": {
    "Message": "Now listening on: https://localhost:5001",
    "address": "https://localhost:5001",
    "{OriginalFormat}": "Now listening on: {address}"
  }
}
{
  "Timestamp": "02:28:21 ",
  "EventId": 14,
  "LogLevel": "Information",
  "Category": "Microsoft.Hosting.Lifetime",
  "Message": "Now listening on: http://localhost:5000",
  "State": {
    "Message": "Now listening on: http://localhost:5000",
    "address": "http://localhost:5000",
    "{OriginalFormat}": "Now listening on: {address}"
  }
}
{
  "Timestamp": "02:28:21 ",
  "EventId": 0,
  "LogLevel": "Information",
  "Category": "Microsoft.Hosting.Lifetime",
  "Message": "Application started. Press Ctrl\u002BC to shut down.",
  "State": {
    "Message": "Application started. Press Ctrl\u002BC to shut down.",
    "{OriginalFormat}": "Application started. Press Ctrl\u002BC to shut down."
  }
}
{
  "Timestamp": "02:28:21 ",
  "EventId": 0,
  "LogLevel": "Information",
  "Category": "Microsoft.Hosting.Lifetime",
  "Message": "Hosting environment: Development",
  "State": {
    "Message": "Hosting environment: Development",
    "envName": "Development",
    "{OriginalFormat}": "Hosting environment: {envName}"
  }
}
{
  "Timestamp": "02:28:21 ",
  "EventId": 0,
  "LogLevel": "Information",
  "Category": "Microsoft.Hosting.Lifetime",
  "Message": "Content root path: .\\snippets\\logging\\console-formatter-json",
  "State": {
    "Message": "Content root path: .\\snippets\\logging\\console-formatter-json",
    "contentRoot": ".\\snippets\\logging\\console-formatter-json",
    "{OriginalFormat}": "Content root path: {contentRoot}"
  }
}

提示

Json 主控台格式器預設會記錄單行內的每則訊息。若要在設定格式器時更容易閱讀，請將 JsonWriterOptions.Indented 設為 true。

警告

使用 Json 主控台格式器時，請勿傳入已序列化為 JSON 的記錄訊息。記錄基礎結構本身已管理記錄訊息的序列化，因此若您要傳入已序列化的記錄訊息，則會進行雙重序列化，導致輸出格式不正確。

設定格式器的組態

先前範例已示範如何以程式設計方式登錄格式器。這也可透過組態來進行。若您更新 appsettings.json 檔案，而不是在 Program.cs 檔案中呼叫 ConfigureLogging，請考慮先前的 Web 應用程式範例原始程式碼，則可取得相同的結果。更新的 appsettings.json 檔案會設定格式器，如下所示：

{
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft": "Warning",
            "Microsoft.Hosting.Lifetime": "Information"
        },
        "Console": {
            "LogLevel": {
                "Default": "Information",
                "Microsoft": "Warning",
                "Microsoft.Hosting.Lifetime": "Information"
            },
            "FormatterName": "json",
            "FormatterOptions": {
                "SingleLine": true,
                "IncludeScopes": true,
                "TimestampFormat": "HH:mm:ss ",
                "UseUtcTimestamp": true,
                "JsonWriterOptions": {
                    "Indented": true
                }
            }
        }
    },
    "AllowedHosts": "*"
}

需要設定的兩個機碼值為 "FormatterName" 和 "FormatterOptions"。若格式器已設定 "FormatterName" 的值，則會選取該格式器且可設定其屬性 (只要是作為 "FormatterOptions" 節點內的機碼)。預先定義的格式器名稱會保留於 ConsoleFormatterNames 底下：

實作自訂格式器

若要實作自訂格式器，您必須：

建立 ConsoleFormatter 的子類別，代表您的自訂格式器
使用下列項目登錄您的自訂格式器
- ConsoleLoggerExtensions.AddConsole
- ConsoleLoggerExtensions.AddConsoleFormatter<TFormatter,TOptions>(ILoggingBuilder, Action<TOptions>)

建立可為您處理此問題的擴充方法：

using Microsoft.Extensions.Logging;

namespace Console.ExampleFormatters.Custom;

public static class ConsoleLoggerExtensions
{
    public static ILoggingBuilder AddCustomFormatter(
        this ILoggingBuilder builder,
        Action<CustomOptions> configure) =>
        builder.AddConsole(options => options.FormatterName = "customName")
            .AddConsoleFormatter<CustomFormatter, CustomOptions>(configure);
}

CustomOptions 定義如下：

using Microsoft.Extensions.Logging.Console;

namespace Console.ExampleFormatters.Custom;

public sealed class CustomOptions : ConsoleFormatterOptions
{
    public string? CustomPrefix { get; set; }
}

在上述程式碼中，選項為 ConsoleFormatterOptions 的子類別。

AddConsoleFormatter API：

登錄 ConsoleFormatter 的子類別
處理組態：
- 根據選項模式和 IOptionsMonitor 介面，使用變更權杖來同步更新

using Console.ExampleFormatters.Custom;
using Microsoft.Extensions.Logging;

using ILoggerFactory loggerFactory =
    LoggerFactory.Create(builder =>
        builder.AddCustomFormatter(options =>
            options.CustomPrefix = " ~~~~~ "));

ILogger<Program> logger = loggerFactory.CreateLogger<Program>();
using (logger.BeginScope("TODO: Add logic to enable scopes"))
{
    logger.LogInformation("Hello World!");
    logger.LogInformation("TODO: Add logic to enable timestamp and log level info.");
}

定義 ConsoleFormatter 的 CustomFormatter 子類別：

using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Logging.Console;
using Microsoft.Extensions.Options;

namespace Console.ExampleFormatters.Custom;

public sealed class CustomFormatter : ConsoleFormatter, IDisposable
{
    private readonly IDisposable? _optionsReloadToken;
    private CustomOptions _formatterOptions;

    public CustomFormatter(IOptionsMonitor<CustomOptions> options)
        // Case insensitive
        : base("customName") =>
        (_optionsReloadToken, _formatterOptions) =
            (options.OnChange(ReloadLoggerOptions), options.CurrentValue);

    private void ReloadLoggerOptions(CustomOptions options) =>
        _formatterOptions = options;

    public override void Write<TState>(
        in LogEntry<TState> logEntry,
        IExternalScopeProvider? scopeProvider,
        TextWriter textWriter)
    {
        string? message =
            logEntry.Formatter?.Invoke(
                logEntry.State, logEntry.Exception);

        if (message is null)
        {
            return;
        }

        CustomLogicGoesHere(textWriter);
        textWriter.WriteLine(message);
    }

    private void CustomLogicGoesHere(TextWriter textWriter)
    {
        textWriter.Write(_formatterOptions.CustomPrefix);
    }

    public void Dispose() => _optionsReloadToken?.Dispose();
}

上述 CustomFormatter.Write<TState> API 會指示包裝各記錄訊息的文字。標準 ConsoleFormatter 至少應可包裝記錄的範圍、時間戳記和嚴重性層級。此外，您也可在記錄訊息中編碼 ANSI 色彩，並提供所需的縮排。 CustomFormatter.Write<TState> 的實作缺少這些功能。

如需進一步自訂格式的靈感，請參閱 Microsoft.Extensions.Logging.Console 命名空間中的現有實作：

自訂組態選項

若要進一步自訂記錄擴充性，您可設定任何組態提供者的衍生 ConsoleFormatterOptions 類別。例如，您可使用 JSON 組態提供者來定義自訂選項。首先定義您的 ConsoleFormatterOptions 子類別。

using Microsoft.Extensions.Logging.Console;

namespace Console.ExampleFormatters.CustomWithConfig;

public sealed class CustomWrappingConsoleFormatterOptions : ConsoleFormatterOptions
{
    public string? CustomPrefix { get; set; }

    public string? CustomSuffix { get; set; }
}

上述主控台格式器選項類別會定義兩個自訂屬性，代表前置詞和後置詞。接著定義 appsettings.json 檔案，以設定主控台格式器選項。

{
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft": "Warning",
            "Microsoft.Hosting.Lifetime": "Information"
        },
        "Console": {
            "LogLevel": {
                "Default": "Information",
                "Microsoft": "Warning",
                "Microsoft.Hosting.Lifetime": "Information"
            },
            "FormatterName": "CustomTimePrefixingFormatter",
            "FormatterOptions": {
                "CustomPrefix": "|-<[",
                "CustomSuffix": "]>-|",
                "SingleLine": true,
                "IncludeScopes": true,
                "TimestampFormat": "HH:mm:ss.ffff ",
                "UseUtcTimestamp": true,
                "JsonWriterOptions": {
                    "Indented": true
                }
            }
        }
    },
    "AllowedHosts": "*"
}

在上述 JSON 組態檔中：

"Logging" 節點會定義 "Console"。
"Console" 節點指定 "CustomTimePrefixingFormatter" 的 "FormatterName"，其對應至自訂格式器。
"FormatterOptions" 節點會定義 "CustomPrefix" 和 "CustomSuffix"，以及其他幾個衍生選項。

提示

系統會保留 $.Logging.Console.FormatterOptions JSON 路徑，在使用 ConsoleFormatterOptions 擴充方法新增路徑時將對應至自訂的 AddConsoleFormatter。除了既有屬性以外，這可提供定義自訂屬性的功能。

請考慮下列 CustomDatePrefixingFormatter：

using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Logging.Console;
using Microsoft.Extensions.Options;

namespace Console.ExampleFormatters.CustomWithConfig;

public sealed class CustomTimePrefixingFormatter : ConsoleFormatter, IDisposable
{
    private readonly IDisposable? _optionsReloadToken;
    private CustomWrappingConsoleFormatterOptions _formatterOptions;

    public CustomTimePrefixingFormatter(
        IOptionsMonitor<CustomWrappingConsoleFormatterOptions> options)
        // Case insensitive
        : base(nameof(CustomTimePrefixingFormatter))
    {
        _optionsReloadToken = options.OnChange(ReloadLoggerOptions);
        _formatterOptions = options.CurrentValue;
    }

    private void ReloadLoggerOptions(CustomWrappingConsoleFormatterOptions options) =>
        _formatterOptions = options;

    public override void Write<TState>(
        in LogEntry<TState> logEntry,
        IExternalScopeProvider? scopeProvider,
        TextWriter textWriter)
    {
        string message =
            logEntry.Formatter(
                logEntry.State, logEntry.Exception);

        if (message == null)
        {
            return;
        }

        WritePrefix(textWriter);
        textWriter.Write(message);
        WriteSuffix(textWriter);
    }

    private void WritePrefix(TextWriter textWriter)
    {
        DateTime now = _formatterOptions.UseUtcTimestamp
            ? DateTime.UtcNow
            : DateTime.Now;

        textWriter.Write($"""
            {_formatterOptions.CustomPrefix} {now.ToString(_formatterOptions.TimestampFormat)}
            """);
    }

    private void WriteSuffix(TextWriter textWriter) =>
        textWriter.WriteLine($" {_formatterOptions.CustomSuffix}");

    public void Dispose() => _optionsReloadToken?.Dispose();
}

在上述格式器實作中：

系統會監視 CustomWrappingConsoleFormatterOptions 是否有變更，並據以更新。
系統會以設定的前置詞和後置詞包裝寫入的訊息。
系統會使用設定的 ConsoleFormatterOptions.UseUtcTimestamp 和 ConsoleFormatterOptions.TimestampFormat 值，將時間戳記加在前置詞之後、訊息之前。

若要使用自訂群組態選項搭配自訂格式器實作，請在呼叫 ConfigureLogging(IHostBuilder, Action<HostBuilderContext,ILoggingBuilder>) 時進行新增。

using Console.ExampleFormatters.CustomWithConfig;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);

builder.Logging.AddConsole()
    .AddConsoleFormatter<
        CustomTimePrefixingFormatter, CustomWrappingConsoleFormatterOptions>();

using IHost host = builder.Build();

ILoggerFactory loggerFactory = host.Services.GetRequiredService<ILoggerFactory>();
ILogger<Program> logger = loggerFactory.CreateLogger<Program>();

using (logger.BeginScope("Logging scope"))
{
    logger.LogInformation("Hello World!");
    logger.LogInformation("The .NET developer community happily welcomes you.");
}

下列主控台輸出與您使用此 CustomTimePrefixingFormatter 預期看到的內容類似。

|-<[ 15:03:15.6179 Hello World! ]>-|
|-<[ 15:03:15.6347 The .NET developer community happily welcomes you. ]>-|

實作自訂色彩格式

若要在自訂記錄格式器中正確啟用色彩功能，您可擴充 SimpleConsoleFormatterOptions，因為其中具有 SimpleConsoleFormatterOptions.ColorBehavior 屬性，可用於啟用記錄中的色彩。

建立由 SimpleConsoleFormatterOptions 衍生的 CustomColorOptions：

using Microsoft.Extensions.Logging.Console;

namespace Console.ExampleFormatters.Custom;

public class CustomColorOptions : SimpleConsoleFormatterOptions
{
    public string? CustomPrefix { get; set; }
}

接著，在 TextWriterExtensions 類別中撰寫一些擴充方法，以便在格式化的記錄訊息中內嵌 ANSI 程式碼的色彩：

namespace Console.ExampleFormatters.Custom;

public static class TextWriterExtensions
{
    const string DefaultForegroundColor = "\x1B[39m\x1B[22m";
    const string DefaultBackgroundColor = "\x1B[49m";

    public static void WriteWithColor(
        this TextWriter textWriter,
        string message,
        ConsoleColor? background,
        ConsoleColor? foreground)
    {
        // Order:
        //   1. background color
        //   2. foreground color
        //   3. message
        //   4. reset foreground color
        //   5. reset background color

        var backgroundColor = background.HasValue ? GetBackgroundColorEscapeCode(background.Value) : null;
        var foregroundColor = foreground.HasValue ? GetForegroundColorEscapeCode(foreground.Value) : null;

        if (backgroundColor != null)
        {
            textWriter.Write(backgroundColor);
        }
        if (foregroundColor != null)
        {
            textWriter.Write(foregroundColor);
        }

        textWriter.WriteLine(message);

        if (foregroundColor != null)
        {
            textWriter.Write(DefaultForegroundColor);
        }
        if (backgroundColor != null)
        {
            textWriter.Write(DefaultBackgroundColor);
        }
    }

    static string GetForegroundColorEscapeCode(ConsoleColor color) =>
        color switch
        {
            ConsoleColor.Black => "\x1B[30m",
            ConsoleColor.DarkRed => "\x1B[31m",
            ConsoleColor.DarkGreen => "\x1B[32m",
            ConsoleColor.DarkYellow => "\x1B[33m",
            ConsoleColor.DarkBlue => "\x1B[34m",
            ConsoleColor.DarkMagenta => "\x1B[35m",
            ConsoleColor.DarkCyan => "\x1B[36m",
            ConsoleColor.Gray => "\x1B[37m",
            ConsoleColor.Red => "\x1B[1m\x1B[31m",
            ConsoleColor.Green => "\x1B[1m\x1B[32m",
            ConsoleColor.Yellow => "\x1B[1m\x1B[33m",
            ConsoleColor.Blue => "\x1B[1m\x1B[34m",
            ConsoleColor.Magenta => "\x1B[1m\x1B[35m",
            ConsoleColor.Cyan => "\x1B[1m\x1B[36m",
            ConsoleColor.White => "\x1B[1m\x1B[37m",

            _ => DefaultForegroundColor
        };

    static string GetBackgroundColorEscapeCode(ConsoleColor color) =>
        color switch
        {
            ConsoleColor.Black => "\x1B[40m",
            ConsoleColor.DarkRed => "\x1B[41m",
            ConsoleColor.DarkGreen => "\x1B[42m",
            ConsoleColor.DarkYellow => "\x1B[43m",
            ConsoleColor.DarkBlue => "\x1B[44m",
            ConsoleColor.DarkMagenta => "\x1B[45m",
            ConsoleColor.DarkCyan => "\x1B[46m",
            ConsoleColor.Gray => "\x1B[47m",

            _ => DefaultBackgroundColor
        };
}

自訂色彩格式器可套用自訂色彩，其定義如下：

using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Logging.Console;
using Microsoft.Extensions.Options;

namespace Console.ExampleFormatters.Custom;

public sealed class CustomColorFormatter : ConsoleFormatter, IDisposable
{
    private readonly IDisposable? _optionsReloadToken;
    private CustomColorOptions _formatterOptions;

    private bool ConsoleColorFormattingEnabled =>
        _formatterOptions.ColorBehavior == LoggerColorBehavior.Enabled ||
        _formatterOptions.ColorBehavior == LoggerColorBehavior.Default &&
        System.Console.IsOutputRedirected == false;

    public CustomColorFormatter(IOptionsMonitor<CustomColorOptions> options)
        // Case insensitive
        : base("customName") =>
        (_optionsReloadToken, _formatterOptions) =
            (options.OnChange(ReloadLoggerOptions), options.CurrentValue);

    private void ReloadLoggerOptions(CustomColorOptions options) =>
        _formatterOptions = options;

    public override void Write<TState>(
        in LogEntry<TState> logEntry,
        IExternalScopeProvider? scopeProvider,
        TextWriter textWriter)
    {
        if (logEntry.Exception is null)
        {
            return;
        }

        string? message =
            logEntry.Formatter?.Invoke(
                logEntry.State, logEntry.Exception);

        if (message is null)
        {
            return;
        }

        CustomLogicGoesHere(textWriter);
        textWriter.WriteLine(message);
    }

    private void CustomLogicGoesHere(TextWriter textWriter)
    {
        if (ConsoleColorFormattingEnabled)
        {
            textWriter.WriteWithColor(
                _formatterOptions.CustomPrefix ?? string.Empty,
                ConsoleColor.Black,
                ConsoleColor.Green);
        }
        else
        {
            textWriter.Write(_formatterOptions.CustomPrefix);
        }
    }

    public void Dispose() => _optionsReloadToken?.Dispose();
}

當您執行應用程式時，記錄會在 FormatterOptions.ColorBehavior 為 Enabled 時以綠色顯示 CustomPrefix 訊息。

注意

當 LoggerColorBehavior 為 Disabled 時，記錄訊息不會解譯記錄訊息中的內嵌 ANSI 色彩代碼，而是會輸出原始訊息。例如，請考慮下列項目：

logger.LogInformation("Random log \x1B[42mwith green background\x1B[49m message");

如此會輸出逐字字串，且不會標示色彩。

Random log \x1B[42mwith green background\x1B[49m message