在ASP.NET Web API中，当我们的API发生改变，就涉及到版本问题了。如何实现API的版本呢？

 

1、通过路由设置版本

 

最简单的一种方式是通过路由设置，不同的路由，不同的版本，不同的controller。

 

config.Routes.MapHttpRoute(    name: "Food",    routeTemplate: "api/v1/nutrition/foods/{foodid}",    defaults:...)config.Routes.MapHttpRoute(    name: "Foodv2",    routeTemplate: "api/v2/nutrition/foods/{foodid}",    defaults:...)

 

2、通过HttpControllerSelector

 

通过更改HttpControllerSelector也可以实现。

 

首先写一个继承 DefaultHttpControllerSelector的类。

 

using System.Web.http.Dispatcherpublic class CountingKsControllerSelector : DefaultHttpControllerSelector{    private HttpConfiguraion _config;        public CountgKsControllerSelector(HttpConfiguraiton cofig) : base(config)    {        _config = config;    }        //设计就是返回HttpControllerDesriptor的过程    public override System.Web.Http.Controllers.HttpControllerDescriptor SelectController(HttpRequestMessage request)    {        //获取所有的controller键值集合        var controllers = GetControllerMapping();                //获取路由数据        var routeData = request.GetRouteData();                //从路由中获取当前controller的名称        var controllerName = (string)routeData.Values["controller"];                HttpControllerDescriptor descriptor;                if(controllers.TryGetValue(controllerName, out descriptor))        {            var version = "2";                        //从QueryString中获取版本             var newName = string.Concat(controllerName, "V", version);                        HttpControllerDescriptor versionedDescriptor;                        if(controllers.TryGetValue(newName, out versionedDescriptor))            {                return versionedDescriptor;            }                        return descriptor;        }                return null;            }}

 

在WebApiConfig.cs注册自定义的ControllerSelector

 

config.Services.Replace(typeof(IHttpControllerSelector), new CountingKsControllerSelector(config) );

 

以上是大致的实现思路。具体来说可以通过如下几种方式实现。

 

■ 通过Query String实现版本

客户端大致这样请求：

http://localhost:8901/api/nutrition/foods/4492/measures/7269?v=2

 

using System.Web.http.Dispatcherpublic class CountingKsControllerSelector : DefaultHttpControllerSelector{    private HttpConfiguraion _config;        public CountgKsControllerSelector(HttpConfiguraiton cofig) : base(config)    {        _config = config;    }        //设计就是返回HttpControllerDesriptor的过程    public override System.Web.Http.Controllers.HttpControllerDescriptor SelectController(HttpRequestMessage request)    {        //获取所有的controller键值集合        var controllers = GetControllerMapping();                //获取路由数据        var routeData = request.GetRouteData();                //从路由中获取当前controller的名称        var controllerName = (string)routeData.Values["controller"];                HttpControllerDescriptor descriptor;                if(controllers.TryGetValue(controllerName, out descriptor))        {            //var version = "2";                        //从QueryString中获取版本             var version = GetVersionFromQueryString(request);                        var newName = string.Concat(controllerName, "V", version);                        HttpControllerDescriptor versionedDescriptor;                        if(controllers.TryGetValue(newName, out versionedDescriptor))            {                return versionedDescriptor;            }                        return descriptor;        }                return null;            }        //从QueryString中获取版本     private string GetVersionFromQueryString(HttpRequestMessage request)    {        var query = HttpUtility.ParseQueryString(request.RequestUri.Query);        var version = query["v"];        if(version != null)        {            return version;        }                return "1";    }}

 

■ 通过Header实现版本

客户端大致这样请求：

User-Agent:Fiddler

Host:locahohost:8901

X-CountingKs-Version:2

 

private string GetVersionFromHeader(HttpRequestMessage request){    const string HEADER_NAME = "X-CountingKs-Version";        if(request.Headers.Contains(HEADER_NAME))    {        var header = request.Headers.GetValues(HEADER_NAME).FirstOrDefault();                if(header != null)        {            return header;        }    }    return "1";}

 

■ 通过Accept-Header实现版本

客户端大致这样请求：

User-Agent:Fiddler

Host:locahohost:8901

Accept: application/json;version=2

 

private string GetVersionFromAcceptHeaderVersion(HttpRequestMessage request){    var accept = request.Headers.Accept;        foreach(var mime in accept)    {        if(mime.MediaType == "applicaiton/json")        {            var value = mime.Parameters                .Where(v => v.Name.Equals("version",StringComparison.OrdinalIngoreCase))                .FirstOrDefault();                        return value.Value;        }    }        return "1";    }

 

■ 通过MediaType实现版本

在WebApiConfig.cs中

 

var jsonFormatter = config.Formatters.OfType
     
      ().FirstOrDefault();jsonFormatter.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();CreateMediaTypes(jsonFormatter);private static void CreateMediaTypes(JsonMediaTypeFormatter jsonFormatter){    var mediaTypes = new string[]    {        "application/vnd.counting,s.food.v1+json",        "application/vnd.countingks.measure.v1+json",        "application/vnd.countgks.measure.v2+json",        "applicatikon/vnd.countingks.diary.v1+json",        "application/vnd.countingks.diaryEntry.v1+json"    };        foreach(var mediaType in mediaTypes)    {        jsonFormatter.SupportedMeidaTypes.Add(new MediaTypeHeaderValue(mediaType));    }}
     

 

在客户端大致这样请求：

User-Agent:Fiddler

Host:localhost:8901

Accept:application/vnd.countingks.food.v1+json

 

private string GetVersonFromMediaType(HttpRequestMessage request){    var accept = request.Headers.Accept;    var ex = new Regex(@"application\/vnd\.countingks\.([a-z]+)\.v([0-9]+)\+json". RegexOptions.IgnoreCase);        foreach(var mime in accept)    {        var match = ex.Match(mime.MediaType);        if(match != null)        {            return match.Groups[2].Value;        }    }    return "1";}

 

■ 使用SDammann.WebApi.Versioning

https://github.com/Sebazzz/SDammann.WebApi.Versioning