打造适用于c#的feign - KavinDavid
source link: https://www.cnblogs.com/pokemon/p/11412051.html
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打造适用于c#的feign
之前因为工作原因使用spring cloud全家桶开发过若干项目,发现其中的feign非常好用,以前开发接口客户端的时候都是重复使用HttpClient实现业务,每次新增接口都十分繁琐,故萌生了自定义一个feign.net的想法,直到最近辞去工作后有了时间着手开发. 关于feign的介绍就不多说了,网上有大量的资料.
个人无太多精力复制feign的全部功能,只挑一些比较重要的来实现.
首先定义一个 FeignClientAttribute,其中的Fallback和FallbackFactory主要用于服务降级.
FeignClientAttribute
FeignClientLifetime为服务的生命周期
FeignClientLifetime
定义RequestMapping
RequestMappingAttribute
定义PathVariableAttribute等
PathVariableAttribute等
为了方便扩展,定义一个管道,里面包含了服务实例初始化,发送前,发送后等的事件.
FeignClientPipeline
基本的声明有了,然后开始实现动态生成代理类型代码.
先定义一个Proxy父类
View Code
ServiceDiscoveryHttpClientHandler
接下来开始生成代理类
TypeBuilder
CreateTypeBuilder
BuildConstructor
重写父类只读属性
BuildReadOnlyProperty
//serviceId
BuildReadOnlyProperty(typeBuilder, serviceType, "ServiceId", serviceType.GetCustomAttribute<FeignClientAttribute>().Name);
//baseUri
BuildReadOnlyProperty(typeBuilder, serviceType, "BaseUri", serviceType.GetCustomAttribute<RequestMappingAttribute>()?.Value);
// url
if (serviceType.GetCustomAttribute<FeignClientAttribute>().Url != null)
{
BuildReadOnlyProperty(typeBuilder, serviceType, "Url", serviceType.GetCustomAttribute<FeignClientAttribute>().Url);
}
typeBuilder.AddInterfaceImplementation(serviceType);
接下来是最重要的,读取声明服务的所有方法,全部生成到代理类中
foreach (var method in serviceType.GetMethods())
{
methodBuilder.BuildMethod(typeBuilder, serviceType, method, feignClientAttribute);
}
View Code
最后看看效果
声明的服务
Service
生成的dll代码
Proxy Service
接下来测试一下
AddFeignClients
AddTestFeignClients
public void ConfigureServices(IServiceCollection services)
{
services.Configure<CookiePolicyOptions>(options =>
{
// This lambda determines whether user consent for non-essential cookies is needed for a given request.
options.CheckConsentNeeded = context => true;
options.MinimumSameSitePolicy = SameSiteMode.None;
});
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
// services.AddDiscoveryClient(Configuration);
services.AddFeignClients()
.AddTestFeignClients()
//.AddSteeltoeServiceDiscovery()
;
}
[Route("api/[controller]")]
[ApiController]
public class ValuesController : ControllerBase
{
// GET api/values/5
[HttpGet("{id}")]
public async Task<ActionResult<object>> Get(int id, [FromServices] ITestService testService/*, [FromServices] ITestService1 testService1*/)
{
await testService.PostValueAsync();
//string html = await testService1.GetHtml();
//return html;
//var rrr = typeof(Func<Task>).GetConstructors(System.Reflection.BindingFlags.Default);
//IServiceCollection serviceCollection = HttpContext.RequestServices.GetService(typeof(IServiceCollection)) as IServiceCollection;
//testService.GetValueVoidAsync(id, null, new TestServiceParam
//{
// Name = "asasdsad"
//});
//return await testService.GetValueAsync(id, "asdasd");
//await testService.PostValueForm2Async(id, "", new TestServiceParam
//{
// Name = "testName"
//}, new TestServiceParam
//{
// Name = "name"
//});
//testService.GetValueVoid(id, new TestServiceParam
//{
// Name = "testName"
//}, new TestServiceParam
//{
// Name = "name"
//});
//await testService.PostValueAsync();
//await testService.PostValueAsync(id, "", new TestServiceParam());
//return testService.GetQueryResultValue(id.ToString(), new TestServiceParam
//{
// Name = "asasdsad"
//});
//return await testService.GetQueryResultValueAsync(id.ToString(), new TestServiceParam
//{
// Name = "asasdsad"
//});
testService.GetValueVoidAsync(id, "", null);
return "ok";
}
}
正常工作了!
目前只支持简单的服务降级操作,没有实现Hystrix.
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