Flutter 颤振web调用.net核心api错误'；访问控制允许原点'；

颤振对.net核心api的web调用错误“访问控制允许源”

帮助我我想要颤振Web调用api

我使用.net核心api

如何在.net核心api上允许“访问控制允许源”

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();
            });
        }
    }
}

---

该错误意味着由于CORS策略，您的api（与颤振无关）已阻止请求。CORS阻止来自其他IP的请求。所以你必须启用它

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

遵循指导原则和答案。尝试搜索特定的asp.net核心版本。此外，还需要控制器顶部的

EnableCors

属性才能工作。您的“仅允许特定来源”根本不指定任何类型的主机。它仅指定策略的名称，而且您还未在

服务中使用