Content
//获取或设置报文主体，即客户端提交的数据，返回一个HttpContent

Headers
//获取客户端请求的头部信息集合，可通过在其上调用GetValues(string headerKey)来获取请求头信息

//根据id查询产品
        public Product Get( int id )
        {
            return products.Single( p => p.Id == id );
        }

//查询所有产品
        public IEnumerable<Product> GetAll( )
        {
            return products;
        }

//添加产品
        public Product Add( Product item )
        {
            item.Id = nextId++;
            products.Add( item );
            return item;
        }

//删除产品
        public void Remove( int id )
        {
            products.RemoveAt( id );
        }

//修改产品
        public bool Update( Product item )
        {
            var product=products.Single( p => p.Id == item.Id );
            products.Remove( product );
            products.Add( item );
            return true;
        }
    }
}

namespace API
{
    public static class WebApiConfig
    {
        public static void Register( HttpConfiguration config )
        {
            // Web API 配置和服务
            // Web API configuration and services
            var json = config.Formatters.JsonFormatter;
            // 解决json序列化时的循环引用问题
            json.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
            // 干掉XML序列化器
            config.Formatters.Remove( config.Formatters.XmlFormatter );

var jsonFormatter = config.Formatters.OfType<JsonMediaTypeFormatter>( ).First( );
            jsonFormatter.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver( );
        }
    }
}

namespace ClientCallWebAPI
{
    public class Product
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Category { get; set; }
        public decimal Price { get; set; }
    }

class Program
    {
        static void Main( string[] args )
        {
            HttpClient request = new HttpClient( ); //创建发送请求的http对象
            request.BaseAddress = new Uri( "http://localhost:54838" ); //请求的地址主机名和端口号或域名        
            request.DefaultRequestHeaders.Add( "Accept", "application/json" );//添加Accept报头，定义我能接受的从服务端返回的数据类型
            //发起异步请求，等待返回一个http报文
            //request.GetAsync( "/api/products/1" );  根据id查询产品
            //request.GetAsync( "/api/products" );  查询所有产品
            //request.GetAsync( "/api/products?category=图书" ); 根据类别查询产品 
            HttpResponseMessage response = request.GetAsync( "/api/products?category=图书" ).Result; 
            if (!response.IsSuccessStatusCode) Console.WriteLine( "服务端无响应" );
            string json= response.Content.ReadAsAsync<string>( ).Result; //读取http报文
           
            IEnumerable<Product> products = JsonConvert.DeserializeObject<IEnumerable<Product>>( json );
            if (!products.Any( ))
            {
                Console.WriteLine( $"{response.StatusCode}{response.ReasonPhrase}" );
                return;
            }
            foreach (var item in products)
            {
                Console.WriteLine( $"{item.Id}   {item.Name}   {item.Category}   {item.Price}" );
            }
        }
    }
}

/// <summary>
        /// 检查IP地址格式
        /// </summary>
        /// <param name="ip"></param>
        /// <returns></returns>
        public static bool IsIP( string ip )
        {
            return System.Text.RegularExpressions.Regex.IsMatch( ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$" );
        }
    }
}

using System.Web.Http;
using System.Net;
using System.Net.Http;
using System.Web.Http.Filters;
using System.Diagnostics;
using Newtonsoft.Json;

namespace API.App_Start
{
    /// <summary>
    /// Http错误过滤器
    /// </summary>
    public class HttpErrorFilterAttribute: ExceptionFilterAttribute
    {
        /// <summary>
        /// 过滤Http错误
        /// </summary>
        /// <param name="context"></param>
        public override void OnException( HttpActionExecutedContext context )
        {
            var ex = context.Exception;

//将异常写入日志记录
            Trace.Listeners.Add( new TextWriterTraceListener( "f:/logforHttpError.txt" ) );
            Trace.AutoFlush = true;
            Trace.WriteLine( $"异常发生时间：{DateTime.Now.ToString( "yyyy-MM-dd HH:mm:ss" )}  " +
                $"异常类型：{context.Exception.GetType( ).ToString( )}"+
                $"堆栈信息：{context.Exception.Message}{context.Exception.StackTrace}"
                );

//无实现
            if (ex is NotImplementedException)
            {
                object jsonMsg = new { errorType = ex.GetType( ).ToString( ), message = ex.Message, statusCode = (int)HttpStatusCode.NotImplemented };
                string jsonMsgStr = JsonConvert.SerializeObject( jsonMsg );
                context.Exception= new HttpResponseException( new HttpResponseMessage( HttpStatusCode.NotImplemented )
                {
                    Content = new StringContent( jsonMsgStr ),
                    ReasonPhrase = "请求无实现"
                } );

}

//超时
            else if (ex is TimeoutException)
            {
                object jsonMsg = new { errorType = ex.GetType( ).ToString( ), message = ex.Message, statusCode = (int)HttpStatusCode.RequestTimeout };
                string jsonMsgStr = JsonConvert.SerializeObject( jsonMsg );
                context.Exception = new HttpResponseException( new HttpResponseMessage( HttpStatusCode.RequestTimeout )
                {
                    Content = new StringContent( jsonMsgStr ),
                    ReasonPhrase = "请求超时"
                } );
            }

//服务器内部错误
            else
            {
                object jsonMsg = new { errorType = ex.GetType( ).ToString( ), message = ex.Message, statusCode = (int)HttpStatusCode.InternalServerError };
                string jsonMsgStr = JsonConvert.SerializeObject( jsonMsg );
                context.Exception = new HttpResponseException( new HttpResponseMessage( HttpStatusCode.InternalServerError )
                {
                    Content = new StringContent( jsonMsgStr ),
                    ReasonPhrase = "内部服务器错误"
                } );
            }
            base.OnException( context );
        }
    }
}