Flutter web调用.net核心应用程序接口错误‘访问-控制-允许-原点’

Question

Flutter web调用.net核心应用程序接口错误‘访问-控制-允许-原点’

帮助我，我想要flutter-Web调用api

我使用.net核心应用编程接口

如何在.net核心接口上允许‘访问-控制-允许-起源’

Startup.cs中的代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace test_api
{
    public class Startup
    {
        readonly string MyAllowSpecificOrigins = "_myAllowSpecificOrigins";
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseCors(MyAllowSpecificOrigins);

            // app.UseResponseCaching();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

Flutter Web error

Answer 1

该错误表示您的api (与flutter无关)由于CORS策略而阻止了该请求。CORS会屏蔽其他IP的请求。因此，您几乎必须启用它。

services.AddCors(options =>
    {
        options.AddPolicy("AllowAll",
            builder =>
            {
                builder
                .AllowAnyOrigin() 
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials();
            });
    });

遵循指南和答案here。尝试搜索您的特定asp.net核心版本。此外，控制器顶部的EnableCors属性是工作所必需的。您的“仅允许特定来源”根本不指定任何类型的主机。它只指定策略的名称，而且您还没有在services中使用过