现在依赖注入在.Net里面已经普及，自己常写一些简单的demo倒是无所谓，但偶尔写一点正式的工程，也免不了要使用一下，于是总结了一下在WPF里面使用依赖注入。

在写简单Demo时候，通常是在MainWindow的构造函数里面直接做初始化，各种变量也都丢在MainWindow类里面。在使用依赖注入后，我发现在App里面完成一些初始化内容更合适，包括MainWindow也通过容器生成，需要注意的是，记得把App.xaml中的 StartupUri更改为 Startup，并把值改为自定义的启动函数，在启动函数里面调用MainWindow的Show方法。

App.xaml.cs

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using NLog;
using NLog.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Net.WebSockets;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
using System.Windows;namespace TradeClient
{/// <summary>/// Interaction logic for App.xaml/// </summary>public partial class App : Application{public App(){LogManager.Configuration.Variables["ProgramName"] = System.Reflection.Assembly.GetExecutingAssembly().GetName().Name;LogManager.Configuration.Variables["StartTime"] = DateTime.Now.ToString("yyyyMMdd-HHmmss");var config = new ConfigurationBuilder().Build();var servicesCollection = new ServiceCollection();servicesCollection.AddLogging(loggingBuilder => loggingBuilder.AddNLog(config));servicesCollection.AddSingleton<ApiDatas>();servicesCollection.AddSingleton<TradeSpiImpl>();servicesCollection.AddSingleton<TradeSpiMiddle>();servicesCollection.AddSingleton<MainWindow>();ServiceProvider = servicesCollection.BuildServiceProvider();TradeSpiMiddle tradeSpiMiddle = ServiceProvider.GetRequiredService<TradeSpiMiddle>();tradeSpiMiddle.InitTradeSpi(ref TradeSpi);int size = Marshal.SizeOf(TradeSpi);TradeSpiPoint = Marshal.AllocHGlobal(size);Marshal.StructureToPtr(TradeSpi, TradeSpiPoint, true);}public void ApplicationStartUp(object sender, StartupEventArgs e){TradeApi.CreateTradeApi();TradeApi.RegisterSpi(TradeSpiPoint);TradeApi.RegisterFront("127.0.0.1", 10001);TradeApi.Init();MainWindow mainWindow = ServiceProvider.GetRequiredService<MainWindow>();mainWindow.Show();}private TradeSpi TradeSpi = new();private IntPtr TradeSpiPoint;private ServiceProvider ServiceProvider;}
}