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WebApiClient高级
老九 edited this page Apr 20, 2019
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过滤器的接口是IApiActionFilterAttribute，WebApiClient提供默认ApiActionFilterAttribute抽象基类，比从IApiActionFilterAttribute实现一个过滤器要简单得多。
这是一个用于调试追踪的过滤器，可以将请求与响应内容写入指定输出目标。如果输出目标是LoggerFactory，需要在HttpApiConfig配置LoggerFactory实例或ServiceProvider实例。
接口或方法使用[TraceFilter]
[TraceFilter(OutputTarget = OutputTarget.Console)] // 输出到控制台窗口
public interface IUserApi : IHttpApi
{
// GET {url}?account={account}&password={password}&something={something}
[HttpGet]
[Timeout(10 * 1000)] // 10s超时
Task<string> GetAboutAsync(
[Url] string url,
UserInfo user,
string something);
}请求之后输出请求信息
var userApi = HttpApi.Resolve<IUserApi>();
var about = await userApi
.GetAboutAsync("webapi/user/about", user, "somevalue");
IUserApi.GetAboutAsync
[REQUEST] 2018-10-08 23:55:25.775
GET /webapi/user/about?Account=laojiu&password=123456&BirthDay=2018-01-01&Gender=1&something=somevalue HTTP/1.1
Host: localhost:9999
[RESPONSE] 2018-10-08 23:55:27.047
This is from NetworkSocket.Http
[TIMESPAN] 00:00:01.2722715[SignFilter]
public interface IUserApi : IHttpApi
{
...
}
class SignFilter : ApiActionFilterAttribute
{
public override Task OnBeginRequestAsync(ApiActionContext context)
{
var sign = DateTime.Now.Ticks.ToString();
context.RequestMessage.AddUrlQuery("sign", sign);
return base.OnBeginRequestAsync(context);
}
}当我们需要为每个请求的url额外的动态添加一个叫sign的参数，这个sign可能和配置文件等有关系，而且每次都需要计算，就可以如上设计与应用一个SignFilter。
全局过滤器的执行优先级比非全局过滤器的要高，且影响全部的请求方法，其要求实现IApiActionFilter接口，并实例化添加到HttpApiConfig的GlobalFilters。像[TraceFilter]等一般过滤器，也是实现了IApiActionFilter接口，也可以添加到GlobalFilters作为全局过滤器。
class MyGlobalFilter : IApiActionFilter
{
public Task OnBeginRequestAsync(ApiActionContext context)
{
// do something
return Task.CompletedTask;
}
public Task OnEndRequestAsync(ApiActionContext context)
{
// do something
return Task.CompletedTask;
}
}添加到GlobalFilters
var myFilter = new MyGlobalFilter();
HttpApi.Register<IUserApi>().ConfigureHttpApiConfig(c =>
{
c.GlobalFilters.Add(myFilter);
}); /// <summary>
/// 表示提供client_credentials方式的token过滤器
/// </summary>
public class TokenFilter : AuthTokenFilter
{
/// <summary>
/// 获取提供Token获取的Url节点
/// </summary>
public string TokenEndpoint { get; private set; }
/// <summary>
/// 获取client_id
/// </summary>
public string ClientId { get; private set; }
/// <summary>
/// 获取client_secret
/// </summary>
public string ClientSecret { get; private set; }
/// <summary>
/// OAuth授权的token过滤器
/// </summary>
/// <param name="tokenEndPoint">提供Token获取的Url节点</param>
/// <param name="client_id">客户端id</param>
/// <param name="client_secret">客户端密码</param>
public TokenFilter(string tokenEndPoint, string client_id, string client_secret)
{
this.TokenEndpoint = tokenEndPoint ?? throw new ArgumentNullException(nameof(tokenEndPoint));
this.ClientId = client_id ?? throw new ArgumentNullException(nameof(client_id));
this.ClientSecret = client_secret ?? throw new ArgumentNullException(nameof(client_secret));
}
/// <summary>
/// 请求获取token
/// 可以使用TokenClient来请求
/// </summary>
/// <returns></returns>
protected override async Task<TokenResult> RequestTokenResultAsync()
{
var tokenClient = new TokenClient(this.TokenEndpoint);
return await tokenClient.RequestClientCredentialsAsync(this.ClientId, this.ClientSecret);
}
/// <summary>
/// 请求刷新token
/// 可以使用TokenClient来刷新
/// </summary>
/// <param name="refresh_token">获取token时返回的refresh_token</param>
/// <returns></returns>
protected override async Task<TokenResult> RequestRefreshTokenAsync(string refresh_token)
{
var tokenClient = new TokenClient(this.TokenEndpoint);
return await tokenClient.RequestRefreshTokenAsync(this.ClientId, this.ClientSecret, refresh_token);
}
}添加到GlobalFilters
var tokenFilter = new TokenFilter ("http://localhost/tokenEndpoint","client","secret");
HttpApi.Register<IUserApi>().ConfigureHttpApiConfig(c =>
{
c.GlobalFilters.Add(tokenFilter);
}); WebApiClient内置很多特性，包含接口级、方法级、参数级的，他们分别是实现了IApiActionAttribute接口、IApiActionFilterAttribute接口、IApiParameterAttribute接口、IApiParameterable接口和IApiReturnAttribute接口的一个或多个接口。
例如服务端要求使用x-www-form-urlencoded提交，由于接口设计不合理，目前要求是提交：fieldX= {X}的json文本&fieldY={Y}的json文本 这里{X}和{Y}都是一个多字段的Model，我们对应的接口是这样设计的：
[HttpHost("/upload")]
ITask<bool> UploadAsync(
[FormField][AliasAs("fieldX")] string xJson,
[FormField][AliasAs("fieldY")] string yJson);显然，我们接口参数为string类型的范围太广，没有约束性，我们希望是这样子
[HttpHost("/upload")]
ITask<bool> UploadAsync([FormFieldJson] X fieldX, [FormFieldJson] Y fieldY);[FormFieldJson]将参数值序列化为Json并做为表单的一个字段内容
[AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false)]
class FormFieldJson: Attribute, IApiParameterAttribute
{
public async Task BeforeRequestAsync(ApiActionContext context, ApiParameterDescriptor parameter)
{
var options = context.HttpApiConfig.FormatOptions;
var json = context.HttpApiConfig.JsonFormatter.Serialize(parameter.Value, options);
var fieldName = parameter.Name;
await context.RequestMessage.AddFormFieldAsync(fieldName, json);
}
}try
{
var user = await userApi.GetByIdAsync("id001");
...
}
catch (HttpStatusFailureException ex)
{
var error = ex.ReadAsAsync<ErrorModel>();
...
}
catch (HttpApiException ex)
{
...
}try
{
var user1 = await userApi
.GetByIdAsync("id001")
.Retry(3, i => TimeSpan.FromSeconds(i))
.WhenCatch<HttpStatusFailureException>();
...
}
catch (HttpStatusFailureException ex)
{
var error = ex.ReadAsAsync<ErrorModel>();
...
}
catch (HttpApiException ex)
{
...
}
catch(Exception ex)
{
...
}在一些场景中，你可能不需要使用async/await异步编程方式，WebApiClient提供了Task对象转换为IObservable对象的扩展，使用方式如下：
var unSubscriber = userApi.GetByIdAsync("id001")
.Retry(3, i => TimeSpan.FromSeconds(i))
.WhenCatch<HttpStatusFailureException>();
.ToObservable().Subscribe(result =>
{
...
}, ex =>
{
...
});