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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。
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
我要评论//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);
}
}
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：
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;
}
}
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