在WPF中，使用控制台输出日志信息

一、背景

之前的项目中，使用Log4NET将日志信息输出到文本文件中。这种方法适用于常看以前的日志信息，却并不适用于实时查看日志。本以为Log4NET可以很方便地通过配置appender来解决这个问题。无奈，个人水平有限，只能够在控制台程序中实现，而在WPF应用中没有解决这个问题。后来将解决方案转win32。通过调用win32函数来直接输出信息到控制台。

二、解决方案

帮助类

public class ConsoleLogHelper
{

[System.Security.SuppressUnmanagedCodeSecurity]
[DllImport("kernel32", CharSet = CharSet.Auto)]
internal static extern bool AllocConsole();

[System.Security.SuppressUnmanagedCodeSecurity]
[DllImport("kernel32", CharSet = CharSet.Auto)]
internal static extern bool FreeConsole();

/// <summary>
/// 在程序启动时，执行一次即可
/// </summary>
public static void OpenConsole()
{
try
{
var consoleTitle = "App Runtime Log";
AllocConsole();
Console.BackgroundColor = ConsoleColor.Black;

Console.CursorVisible = false;
Console.Title = consoleTitle;
}
catch (Exception)
{
throw;
}
}

/// <summary>
/// 该方法只在退出程序时，调用
/// </summary>
public static void CloseConsole()
{
FreeConsole();
}

public static void WriteLine(string msg)
{
Console.WriteLine(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));
Console.WriteLine(msg);
Console.ForegroundColor = ConsoleColor.White;
}
public static void WriteLineError(string msg)
{
Console.ForegroundColor = ConsoleColor.Red;
WriteLine(msg);
}

public static void WriteLineError(Exception ex)
{
WriteLineError(ex.Message);
}

public static void WriteLineInfo(string msg)
{
Console.ForegroundColor = ConsoleColor.Cyan;
WriteLine(msg);
}

}

使用 App.cs

public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
ConsoleLogHelper.OpenConsole();
}

protected override void OnExit(ExitEventArgs e)
{
base.OnExit(e);
ConsoleLogHelper.CloseConsole();
}
}

使用 MainWindow.xaml

<Window x:Class="Log4Net_Appender_Console.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:Log4Net_Appender_Console"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Grid>
<StackPanel>
<Button Click="Button_Click_default"
Width="200"
Height="50">default</Button>
<Button Click="Button_Click_error"
Width="200"
Height="50">error</Button>
<Button Click="Button_Click_exception"
Width="200"
Height="50">exception</Button>
<Button Click="Button_Click_info"
Width="200"
Height="50">info</Button>

</StackPanel>

</Grid>
</Window>

使用 MainWindow.cs

public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}

private void Excute(Action<int> action)
{
for (int i = 0; i < 10; i++)
{
action(i);
}
}

bdd8
private void Button_Click_default(object sender, RoutedEventArgs e)
{
Excute((i)=> {
Console.WriteLine($"default-->{i.ToString()}");
});
}

private void Button_Click_error(object sender, RoutedEventArgs e)
{
Excute((i) => {
ConsoleLogHelper.WriteLineError($"error-->{i.ToString()}");
});
}

private void Button_Click_exception(object sender, RoutedEventArgs e)
{
try
{
string a = null;
a.ToString();
}
catch (Exception ex)
{
Excute((i) => {
ConsoleLogHelper.WriteLineError(ex);
});
}
}

private void Button_Click_info(object sender, RoutedEventArgs e)
{
Excute((i) => {
ConsoleLogHelper.WriteLineInfo($"info-->{i.ToString()}");
});
}
}

三、分析

使用核心函数AllocConsole()在当前线程中打开一个控制台。然后使用Console.WriteLine()将信息输出到控制台。