ASP.NET Web API中实现版本的几种方式

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.Dispatcher

public 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 = "";

            //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.Dispatcher

public 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 "";
    }
}

■ 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 "";
}

■ 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 "";

}

■ 通过MediaType实现版本

在WebApiConfig.cs中

var jsonFormatter = config.Formatters.OfType<JsonMediaTypeFormatter>().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[].Value;
        }
    }
    return "";
}

■ 使用SDammann.WebApi.Versioning

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