Intro
在 ASP.NET core 中中间件的设计令人叹为观止, 如此高大上的设计何不集成到自己的代码里呢.
于是就有了封装了一个简单通用的中间件模板的想法, 以后有需要的时候就可以拿来即用.
接口定义
这里按执行的委托是同步还是异步分为了同步和异步两种构建方法
- // 没有返回值的同步中间件构建器
- public interface IPipelineBuilder<TContext>
- {
- IPipelineBuilder<TContext> Use(Func<Action<TContext>, Action<TContext>> middleware);
- Action<TContext> Build();
- }
- // 异步中间件构建器
- public interface IAsyncPipelineBuilder<TContext>
- {
- IAsyncPipelineBuilder<TContext> Use(Func<Func<TContext, Task>, Func<TContext, Task>> middleware);
- Func<TContext, Task> Build();
- }
为了方便使用, 定义一下扩展方法, 使得可以像 ASP.NET core 中 App.Use(Fun<HttpContext, Func<Task>, Task>) 一样比较方便的使用, 扩展方法定义如下:
- public static IPipelineBuilder<TContext> Use<TContext>(this IPipelineBuilder<TContext> builder, Action<TContext, Action> action)
- {
- return builder.Use(next =>
- context =>
- {
- action(context, () => next(context));
- });
- }
- public static IAsyncPipelineBuilder<TContext> Use<TContext>(this IAsyncPipelineBuilder<TContext> builder, Func<TContext, Func<Task>, Task> func)
- {
- return builder.Use(next =>
- context =>
- {
- return func(context, () => next(context));
- });
- }
为了方便创建对应的 PipelineBuilder , 这里定义了两个方法:
使用 Create 方法就可以创建一个 IPipelineBuilder , 使用 CreateAsync 就可以创建一个 IAsyncPipelineBuilder
- public class PipelineBuilder
- {
- public static IPipelineBuilder<TContext> Create<TContext>(Action<TContext> completeAction)
- {
- return new PipelineBuilder<TContext>(completeAction);
- }
- public static IAsyncPipelineBuilder<TContext> CreateAsync<TContext>(Func<TContext, Task> completeFunc)
- {
- return new AsyncPipelineBuilder<TContext>(completeFunc);
- }
- }
使用示例
来看一个使用示例, 这里的示例修改自设计模式里的责任链模式的一个示例, 废话不说, 来看代码:
这是一个请假的示例, 不同的请假时间交由不同的审批主管进行审批, 最后模拟了从请假 1 小时到请假 8 小时的申请处理情况
- private class RequestContext
- {
- public string RequesterName { get; set; }
- public int Hour { get; set; }
- }
- public static void Test()
- {
- var requestContext = new RequestContext()
- {
- RequesterName = "Kangkang",
- Hour = 12,
- };
- var builder = PipelineBuilder.Create<RequestContext>(context =>
- {
- Console.WriteLine($"{context.RequesterName} {context.Hour}h apply failed");
- })
- .Use((context, next) =>
- {
- if (context.Hour <= 2)
- {
- Console.WriteLine("pass 1");
- }
- else
- {
- next();
- }
- })
- .Use((context, next) =>
- {
- if (context.Hour <= 4)
- {
- Console.WriteLine("pass 2");
- }
- else
- {
- next();
- }
- })
- .Use((context, next) =>
- {
- if (context.Hour <= 6)
- {
- Console.WriteLine("pass 3");
- }
- else
- {
- next();
- }
- })
- ;
- var requestPipeline = builder.Build();
- foreach (var i in Enumerable.Range(1, 8))
- {
- Console.WriteLine();
- Console.WriteLine($"--------- h:{i} apply Pipeline------------------");
- requestContext.Hour = i;
- requestPipeline.Invoke(requestContext);
- Console.WriteLine("----------------------------");
- Console.WriteLine();
- }
- }
- public static async Task AsyncPipelineBuilderTest()
- {
- var requestContext = new RequestContext()
- {
- RequesterName = "Michael",
- Hour = 12,
- };
- var builder = PipelineBuilder.CreateAsync<RequestContext>(context =>
- {
- Console.WriteLine($"{context.RequesterName} {context.Hour}h apply failed");
- return Task.CompletedTask;
- })
- .Use(async (context, next) =>
- {
- if (context.Hour <= 2)
- {
- Console.WriteLine("pass 1");
- }
- else
- {
- await next();
- }
- })
- .Use(async (context, next) =>
- {
- if (context.Hour <= 4)
- {
- Console.WriteLine("pass 2");
- }
- else
- {
- await next();
- }
- })
- .Use(async (context, next) =>
- {
- if (context.Hour <= 6)
- {
- Console.WriteLine("pass 3");
- }
- else
- {
- await next();
- }
- })
- ;
- var requestPipeline = builder.Build();
- foreach (var i in Enumerable.Range(1, 8))
- {
- Console.WriteLine($"--------- h:{i} apply AsyncPipeline------------------");
- requestContext.Hour = i;
- await requestPipeline.Invoke(requestContext);
- Console.WriteLine("----------------------------");
- }
- }
运行效果:
实现代码
- internal class PipelineBuilder<TContext> : IPipelineBuilder<TContext>
- {
- private readonly Action<TContext> _completeFunc;
- private readonly IList<Func<Action<TContext>, Action<TContext>>> _pipelines = new List<Func<Action<TContext>, Action<TContext>>>();
- public PipelineBuilder(Action<TContext> completeFunc)
- {
- _completeFunc = completeFunc;
- }
- public IPipelineBuilder<TContext> Use(Func<Action<TContext>, Action<TContext>> middleware)
- {
- _pipelines.Add(middleware);
- return this;
- }
- public Action<TContext> Build()
- {
- var request = _completeFunc;
- foreach (var pipeline in _pipelines.Reverse())
- {
- request = pipeline(request);
- }
- return request;
- }
- }
- internal class AsyncPipelineBuilder<TContext> : IAsyncPipelineBuilder<TContext>
- {
- private readonly Func<TContext, Task> _completeFunc;
- private readonly IList<Func<Func<TContext, Task>, Func<TContext, Task>>> _pipelines = new List<Func<Func<TContext, Task>, Func<TContext, Task>>>();
- public AsyncPipelineBuilder(Func<TContext, Task> completeFunc)
- {
- _completeFunc = completeFunc;
- }
- public IAsyncPipelineBuilder<TContext> Use(Func<Func<TContext, Task>, Func<TContext, Task>> middleware)
- {
- _pipelines.Add(middleware);
- return this;
- }
- public Func<TContext, Task> Build()
- {
- var request = _completeFunc;
- foreach (var pipeline in _pipelines.Reverse())
- {
- request = pipeline(request);
- }
- return request;
- }
- }
- Reference
来源: https://www.cnblogs.com/weihanli/p/12700006.html