.net core 读取本地指定目录下的文件的实例代码

项目需求

asp.net core 读取log目录下的.log文件，.log文件的内容如下：

xxx.log

------------------------------------------begin---------------------------------
写入时间:2018-09-11 17:01:48
userid=1000
golds=10
-------------------------------------------end---------------------------------

一个 begin end 为一组，同一个.log文件里 userid 相同的，取写入时间最大一组值，所需结果如下：

UserID   Golds   RecordDate
1001     20     2018/9/11 17:10:48
1000     20     2018/9/11 17:11:48
1003     30     2018/9/11 17:12:48
1002     10     2018/9/11 18:01:48
1001     20     2018/9/12 17:10:48
1000     30     2018/9/12 17:12:48
1002     10     2018/9/12 18:01:48

项目结构

Snai.File.FileOperation Asp.net core 2.0 网站

项目实现

新建Snai.File解决方案，在解决方案下新建一个名Snai.File.FileOperation Asp.net core 2.0 空网站

把log日志文件拷备到项目下

修改Startup类的ConfigureServices()方法，注册访问本地文件所需的服务，到时在中间件中通过构造函数注入添加到中间件，这样就可以在一个地方控制文件的访问路径（也就是应用程序启动的时候）

public void ConfigureServices(IServiceCollection services){　　services.AddSingleton<IFileProvider>(new PhysicalFileProvider(Directory.GetCurrentDirectory()));}

新建 Middleware 文件夹，在 Middleware下新建 Entity 文件夹，新建 UserGolds.cs 类，用来保存读取的日志内容，代码如下

namespace Snai.File.FileOperation.Middleware.Entity{ public class UserGolds {  public UserGolds()  {   RecordDate = new DateTime(1970, 01, 01);   UserID = 0;   Golds = 0;  }  public DateTime RecordDate { get; set; }  public int UserID { get; set; }  public int Golds { get; set; } }}

在 Middleware 下新建 FileProviderMiddleware.cs 中间件类，用于读取 log 下所有日志文件内容，并整理成所需的内容格式，代码如下

namespace Snai.File.FileOperation.Middleware{ public class FileProviderMiddleware {  private readonly RequestDelegate _next;  private readonly IFileProvider _fileProvider;  public FileProviderMiddleware(RequestDelegate next, IFileProvider fileProvider)  {   _next = next;   _fileProvider = fileProvider;  }  public async Task Invoke(HttpContext context)  {   var output = new StringBuilder("");   //ResolveDirectory(output, "", "");   ResolveFileInfo(output, "log", ".log");   await context.Response.WriteAsync(output.ToString());  }  //读取目录下所有文件内容  private void ResolveFileInfo(StringBuilder output, string path, string suffix)  {   output.AppendLine("UserID Golds RecordDate");   IDirectoryContents dir = _fileProvider.GetDirectoryContents(path);   foreach (IFileInfo item in dir)   {    if (item.IsDirectory)    {     ResolveFileInfo(output,      item.PhysicalPath.Substring(Directory.GetCurrentDirectory().Length),      suffix);    }    else    {     if (item.Name.Contains(suffix))     {      var userList = new List<UserGolds>();      var user = new UserGolds();      IFileInfo file = _fileProvider.GetFileInfo(path + "//" + item.Name);      using (var stream = file.CreateReadStream())      {       using (var reader = new StreamReader(stream))       {        string content = reader.ReadLine();        while (content != null)        {         if (content.Contains("begin"))         {          user = new UserGolds();         }         if (content.Contains("写入时间"))         {          DateTime recordDate;          string strRecordDate = content.Substring(content.IndexOf(":") + 1).Trim();          if (DateTime.TryParse(strRecordDate, out recordDate))          {           user.RecordDate = recordDate;          }         }         if (content.Contains("userid"))         {          int userID;          string strUserID = content.Substring(content.LastIndexOf("=") + 1).Trim();          if (int.TryParse(strUserID, out userID))          {           user.UserID = userID;          }         }         if (content.Contains("golds"))         {          int golds;          string strGolds = content.Substring(content.LastIndexOf("=") + 1).Trim();          if (int.TryParse(strGolds, out golds))          {           user.Golds = golds;          }         }         if (content.Contains("end"))         {          var userMax = userList.FirstOrDefault(u => u.UserID == user.UserID);          if (userMax == null || userMax.UserID <= 0)          {           userList.Add(user);          }          else if (userMax.RecordDate < user.RecordDate)          {           userList.Remove(userMax);           userList.Add(user);          }         }         content = reader.ReadLine();        }       }      }      if (userList != null && userList.Count > 0)      {       foreach (var golds in userList.OrderBy(u => u.RecordDate))       {        output.AppendLine(golds.UserID.ToString() + " " + golds.Golds + " " + golds.RecordDate);       }       output.AppendLine("");      }     }    }   }  }  //读取目录下所有文件名  private void ResolveDirectory(StringBuilder output, string path, string prefix)  {   IDirectoryContents dir = _fileProvider.GetDirectoryContents(path);   foreach (IFileInfo item in dir)   {    if (item.IsDirectory)    {     output.AppendLine(prefix + "[" + item.Name + "]");     ResolveDirectory(output,      item.PhysicalPath.Substring(Directory.GetCurrentDirectory().Length),      prefix + " ");    }    else    {     output.AppendLine(path + prefix + item.Name);    }   }  } } public static class UseFileProviderExtensions {  public static IApplicationBuilder UseFileProvider(this IApplicationBuilder app)  {   return app.UseMiddleware<FileProviderMiddleware>();  } }}

上面有两个方法 ResolveFileInfo()和ResolveDirectory()

ResolveFileInfo() 读取目录下所有文件内容，也就是需求所用的方法

ResolveDirectory() 读取目录下所有文件名，是输出目录下所有目录和文件名，不是需求所需但也可以用

修改Startup类的Configure()方法，在app管道中使用文件中间件服务

public void Configure(IApplicationBuilder app, IHostingEnvironment env){　　if (env.IsDevelopment())　　{　　　　app.UseDeveloperExceptionPage();　　}　　app.UseFileProvider();　　　　app.Run(async (context) =>　　{　　　　await context.Response.WriteAsync("Hello World!");　　});}

到此所有代码都已编写完成

启动运行项目，得到所需结果，页面结果如下