浅谈ASP.NET Core静态文件处理源码探究_实用技巧_

 //使用默认路径，即wwwroot app.UseStaticFiles(); //或自定义读取路径 var fileProvider = new PhysicalFileProvider($"{env.ContentRootPath}/staticfiles"); app.UseStaticFiles(new StaticFileOptions { RequestPath="/staticfiles", FileProvider = fileProvider });

 public static class StaticFileExtensions { public static IApplicationBuilder UseStaticFiles(this IApplicationBuilder app) { return app.UseMiddleware(); } public static IApplicationBuilder UseStaticFiles(this IApplicationBuilder app, string requestPath) { return app.UseStaticFiles(new StaticFileOptions { RequestPath = new PathString(requestPath) }); } public static IApplicationBuilder UseStaticFiles(this IApplicationBuilder app, StaticFileOptions options) { return app.UseMiddleware(Options.Create(options)); } }

 public class StaticFileOptions : SharedOptionsBase { public StaticFileOptions() : this(new SharedOptions()) { } public StaticFileOptions(SharedOptions sharedOptions) : base(sharedOptions) { OnPrepareResponse = _ => { }; } /// 
 /// 文件类型提供程序,也就是我们常用的文件名对应MimeType的对应关系 /// 
 public IContentTypeProvider ContentTypeProvider { get; set; } /// 
 /// 设置该路径下默认文件输出类型 /// 
 public string DefaultContentType { get; set; } public bool ServeUnknownFileTypes { get; set; } /// 
 /// 文件压缩方式 /// 
 public HttpsCompressionMode HttpsCompression { get; set; } = HttpsCompressionMode.Compress; /// 
 /// 准备输出之前可以做一些自定义操作 /// 
 public Action OnPrepareResponse { get; set; } } public abstract class SharedOptionsBase { protected SharedOptionsBase(SharedOptions sharedOptions) { SharedOptions = sharedOptions; } protected SharedOptions SharedOptions { get; private set; } /// 
 /// 请求路径 /// 
 public PathString RequestPath { get { return SharedOptions.RequestPath; } set { SharedOptions.RequestPath = value; } } /// 
 /// 文件提供程序,在.NET Core中如果需要访问文件相关操作可使用FileProvider文件提供程序获取文件相关信息 /// 
 public IFileProvider FileProvider { get { return SharedOptions.FileProvider; } set { SharedOptions.FileProvider = value; } } }

 var provider = new FileExtensionContentTypeProvider(); provider.Mappings[".myapp"] = "application/x-msdownload"; provider.Mappings[".htm3"] = "text/html"; app.UseStaticFiles(new StaticFileOptions { ContentTypeProvider = provider, //可以在输出之前设置输出相关 OnPrepareResponse = ctx => { ctx.Context.Response.Headers.Append("Cache-Control", $"public, max-age=3600"); } });

 public class StaticFileMiddleware { private readonly StaticFileOptions _options; private readonly PathString _matchUrl; private readonly RequestDelegate _next; private readonly ILogger _logger; private readonly IFileProvider _fileProvider; private readonly IContentTypeProvider _contentTypeProvider; public StaticFileMiddleware(RequestDelegate next, IWebHostEnvironment hostingEnv, IOptions options, ILoggerFactory loggerFactory) { _next = next; _options = options.Value; //设置文件类型提供程序 _contentTypeProvider = options.Value.ContentTypeProvider ?? new FileExtensionContentTypeProvider(); //文件提供程序 _fileProvider = _options.FileProvider ?? Helpers.ResolveFileProvider(hostingEnv); //匹配路径 _matchUrl = _options.RequestPath; _logger = loggerFactory.CreateLogger(); } public Task Invoke(HttpContext context) { //判断是够获取到终结点信息，这也就是为什么我们使用UseStaticFiles要在UseRouting之前 if (!ValidateNoEndpoint(context)) { } //判断HttpMethod，只能是Get和Head操作 else if (!ValidateMethod(context)) { } //判断请求路径是否存在 else if (!ValidatePath(context, _matchUrl, out var subPath)) { } //根据请求文件名称判断是否可以匹配到对应的MimeType，如果匹配到则返回contentType else if (!LookupContentType(_contentTypeProvider, _options, subPath, out var contentType)) { } else { //执行静态文件操作 return TryServeStaticFile(context, contentType, subPath); } return _next(context); } private Task TryServeStaticFile(HttpContext context, string contentType, PathString subPath) { var fileContext = new StaticFileContext(context, _options, _logger, _fileProvider, contentType, subPath); //判断文件是否存在 if (!fileContext.LookupFileInfo()) { _logger.FileNotFound(fileContext.SubPath); } else { //静态文件处理 return fileContext.ServeStaticFile(context, _next); } return _next(context); } }

 internal struct StaticFileContext { private const int StreamCopyBufferSize = 64 * 1024; private readonly HttpContext _context; private readonly StaticFileOptions _options; private readonly HttpRequest _request; private readonly HttpResponse _response; private readonly ILogger _logger; private readonly IFileProvider _fileProvider; private readonly string _method; private readonly string _contentType; private IFileInfo _fileInfo; private EntityTagHeaderValue _etag; private RequestHeaders _requestHeaders; private ResponseHeaders _responseHeaders; private RangeItemHeaderValue _range; private long _length; private readonly PathString _subPath; private DateTimeOffset _lastModified; private PreconditionState _ifMatchState; private PreconditionState _ifNoneMatchState; private PreconditionState _ifModifiedSinceState; private PreconditionState _ifUnmodifiedSinceState; private RequestType _requestType; public StaticFileContext(HttpContext context, StaticFileOptions options, ILogger logger, IFileProvider fileProvider, string contentType, PathString subPath) { _context = context; _options = options; _request = context.Request; _response = context.Response; _logger = logger; _fileProvider = fileProvider; _method = _request.Method; _contentType = contentType; _fileInfo = null; _etag = null; _requestHeaders = null; _responseHeaders = null; _range = null; _length = 0; _subPath = subPath; _lastModified = new DateTimeOffset(); _ifMatchState = PreconditionState.Unspecified; _ifNoneMatchState = PreconditionState.Unspecified; _ifModifiedSinceState = PreconditionState.Unspecified; _ifUnmodifiedSinceState = PreconditionState.Unspecified; //再次判断请求HttpMethod if (HttpMethods.IsGet(_method)) { _requestType = RequestType.IsGet; } else if (HttpMethods.IsHead(_method)) { _requestType = RequestType.IsHead; } else { _requestType = RequestType.Unspecified; } } /// 
 /// 判断文件是否存在 /// 
 public bool LookupFileInfo() { //判断根据请求路径是否可以获取到文件信息 _fileInfo = _fileProvider.GetFileInfo(_subPath.Value); if (_fileInfo.Exists) { //获取文件长度 _length = _fileInfo.Length; //最后修改日期 DateTimeOffset last = _fileInfo.LastModified; _lastModified = new DateTimeOffset(last.Year, last.Month, last.Day, last.Hour, last.Minute, last.Second, last.Offset).ToUniversalTime(); //ETag标识 long etagHash = _lastModified.ToFileTime() ^ _length; _etag = new EntityTagHeaderValue('\"' + Convert.ToString(etagHash, 16) + '\"'); } return _fileInfo.Exists; } /// 
 /// 处理文件输出 /// 
 public async Task ServeStaticFile(HttpContext context, RequestDelega
                
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