.net core 读取本地指定目录下的文件的实例代码

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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