配置跨域

为什么要配置跨域

当你的WebApi和你的HTML JS不在一个站点下面使用ajax 就会报错 

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin

https://www.donet5.com  is therefore not allowed access.

配置跨域

1、打开Startup.cs ，找到ConfigureServices 方法

readonly string MyAllowSpecificOrigins = "_myAllowSpecificOrigins";
public void ConfigureServices(IServiceCollection services)
        {
        
          
            services.AddCors(options =>
            {
   options.AddPolicy(MyAllowSpecificOrigins,
     builder => builder.AllowAnyOrigin()
               .AllowAnyHeader()
              .WithMethods("GET", "POST", "HEAD", "PUT", "DELETE", "OPTIONS")
                );
  });
  
  }

找到Configure 添加一行代码

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseCors(MyAllowSpecificOrigins);//添加这个