我有一个ASP .NET Core自托管项目.我正在从静态文件夹中提供内容(没问题).它可以跨站点提供图像而不会出现问题(CORS标题显示).但是,对于某些文件类型(如
JSON),它们的CORS标头不会显示,并且客户端站点无法查看内容.如果我将文件重命名为未知类型(例如jsonx),它将使用CORS标头提供服务,没问题.如何使用CORS标头来提供服务呢?
我在Startup.cs中设置了以下CORS策略:
public void ConfigureServices(IServiceCollection services) { services.AddCors(options => { options.AddPolicy("CorsPolicy",builder => builder.AllowAnyOrigin() .AllowAnyMethod() .AllowAnyHeader() .AllowCredentials() ); }); // Add framework services. services.AddMvc(); }
以下是我的配置
public void Configure(IApplicationBuilder app,IHostingEnvironment env,ILoggerFactory loggerFactory) { app.UseCors("CorsPolicy"); loggerFactory.AddConsole(Configuration.GetSection("Logging")); loggerFactory.AddDebug(); if (env.IsDevelopment()) { app.UseDeveloperExceptionPage(); app.UsebrowserLink(); } else { app.UseExceptionHandler("/Home/Error"); } // Static File options,normally would be in-line,but the SFO's file provider is not available at instantiation time var sfo = new StaticFileOptions() { ServeUnkNownFileTypes = true,DefaultContentType = "application/octet-stream",RequestPath = "/assets"}; sfo.FileProvider = new PhysicalFileProvider(Program.minervaConfig["ContentPath"]); app.UseStaticFiles(sfo); app.UseMvc(routes => { routes.MapRoute( name: "default",template: "{controller=Home}/{action=Index}/{id?}"); }); }
解决方法
中间件可以帮助处理这种复杂的逻辑.我最近为JavaScript源代码工作了.看起来JSON的媒体类型是“application / json”.
/* using System.Linq; using System.Threading.Tasks; using Microsoft.AspNetCore.Builder; using Microsoft.AspNetCore.Http; Made available under the Apache 2.0 license. https://www.apache.org/licenses/LICENSE-2.0 */ /// <summary> /// Sets response headers for static files having certain media types. /// In Startup.Configure,enable before UseStaticFiles with /// app.UseMiddleware<CorsResponseHeaderMiddleware>(); /// </summary> public class CorsResponseHeaderMiddleware { private readonly RequestDelegate _next; // Must NOT have trailing slash private readonly string AllowedOrigin = "http://server:port"; private bool IsCorsOkContentType(string fieldValue) { var fieldValueLower = fieldValue.ToLower(); // Add other media types here. return (fieldValueLower.StartsWith("application/javascript")); } public CorsResponseHeaderMiddleware(RequestDelegate next) { _next = next; } public async Task Invoke(HttpContext context) { context.Response.OnStarting(ignored => { if (context.Response.StatusCode < 400 && IsCorsOkContentType(context.Response.ContentType)) { context.Response.Headers.Add("Access-Control-Allow-Origin",AllowedOrigin); } return Task.Fromresult(0); },null); await _next(context); } }