.NET MVC5简介(五)管道处理模型IHttpModule
https://www.cnblogs.com/jimmyzhang/archive/2007/09/04/880967.html
ihttpmodule
httpruntime(运行时)。在一个控制台程序中,程序的入口是program中的main方法。那么,一个网站的入口在哪里呢?在最开始的ashx中,有个processrequest方法,后来在webform中,在后台是一个不分类,继承自page类,在page_load方法中去写代码。其实page类型也有一个processrequest的虚方法。
都是这个processrequest方法来处理请求的。在mvc中也是如此。在mvc中,任何一个http请求,一定有一个ihttphandler来处理,在这个接口中,定义了一个processrequest方法。httpapplication继承自ihttphandler接口。任何一个http请求就是一个httpapplication对象来处理的,然后处理过程固定包含权限认证、缓存处理、session处理、cookie出库、生成html、输出客户端,与此同时,千千万万的开发者,又有各种各样的扩展诉求,任何一个环节都有可能扩展,如果是我们来设计,该怎么设计?
其实在mvc框架里面,用到的是观察者模式:
在httpapplication类型,有这些事件:
// // 摘要: // occurs just before asp.net sends http headers to the client. public event eventhandler presendrequestheaders; // // 摘要: // occurs when the handler is selected to respond to the request. public event eventhandler maprequesthandler; // // 摘要: // occurs when the application is disposed. public event eventhandler disposed; // // 摘要: // occurs as the first event in the http pipeline chain of execution when asp.net // responds to a request. public event eventhandler beginrequest; // // 摘要: // occurs when a security module has established the identity of the user. public event eventhandler authenticaterequest; // // 摘要: // occurs when a security module has established the identity of the user. public event eventhandler postauthenticaterequest; // // 摘要: // occurs when a security module has verified user authorization. public event eventhandler authorizerequest; // // 摘要: // occurs when the user for the current request has been authorized. public event eventhandler postauthorizerequest; // // 摘要: // occurs when asp.net finishes an authorization event to let the caching modules // serve requests from the cache, bypassing execution of the event handler (for // example, a page or an xml web service). public event eventhandler resolverequestcache; // // 摘要: // occurs when asp.net bypasses execution of the current event handler and allows // a caching module to serve a request from the cache. public event eventhandler postresolverequestcache; // // 摘要: // occurs just before asp.net sends content to the client. public event eventhandler presendrequestcontent; // // 摘要: // occurs when asp.net has mapped the current request to the appropriate event handler. public event eventhandler postmaprequesthandler; // // 摘要: // occurs when asp.net has completed processing all the event handlers for the system.web.httpapplication.logrequest // event. public event eventhandler postlogrequest; // // 摘要: // occurs when the managed objects that are associated with the request have been // released. public event eventhandler requestcompleted; // // 摘要: // occurs when the request state (for example, session state) that is associated // with the current request has been obtained. public event eventhandler postacquirerequeststate; // // 摘要: // occurs just before asp.net starts executing an event handler (for example, a // page or an xml web service). public event eventhandler prerequesthandlerexecute; // // 摘要: // occurs when the asp.net event handler (for example, a page or an xml web service) // finishes execution. public event eventhandler postrequesthandlerexecute; // // 摘要: // occurs after asp.net finishes executing all request event handlers. this event // causes state modules to save the current state data. public event eventhandler releaserequeststate; // // 摘要: // occurs when asp.net has completed executing all request event handlers and the // request state data has been stored. public event eventhandler postreleaserequeststate; // // 摘要: // occurs when asp.net finishes executing an event handler in order to let caching // modules store responses that will be used to serve subsequent requests from the // cache. public event eventhandler updaterequestcache; // // 摘要: // occurs when asp.net finishes updating caching modules and storing responses that // are used to serve subsequent requests from the cache. public event eventhandler postupdaterequestcache; // // 摘要: // occurs just before asp.net performs any logging for the current request. public event eventhandler logrequest; // // 摘要: // occurs when asp.net acquires the current state (for example, session state) that // is associated with the current request. public event eventhandler acquirerequeststate; // // 摘要: // occurs as the last event in the http pipeline chain of execution when asp.net // responds to a request. public event eventhandler endrequest; // // 摘要: // occurs when an unhandled exception is thrown. public event eventhandler error;
这里用的是观察者模式,把固定的步骤直接卸载handler里面,在步骤前后分别放一个事件,然后开发者可以对事件注册动作,等着请求进来了,然后就可以按照顺讯执行一下。这种设计是不是很完美?但是仍有不完美的地方,就是每个请求都要执行这些事件,太多管闲事了。在.net core中出现了中间件,比这种更加完美。后续再详细介绍。
请见下列代码
public class httpprocessdemo { public class httpapplicationdemo : ihttphandler { public bool isreusable => true; public event action beginrequest; public event action endrequest; public event action presomething1handler; public event action postsomething1handler; public event action presomething2handler; public event action postsomething2handler; public event action presomething3handler; public event action postsomething3handler; public event action presomething4handler; public event action postsomething4handler; public event action presomething5handler; public event action postsomething5handler; public event action presomething6handler; public event action postsomething6handler; public void processrequest(httpcontext context) { this.beginrequest?.invoke(); this.presomething1handler?.invoke(); console.writeline("something 1"); this.postsomething1handler?.invoke(); this.presomething2handler?.invoke(); console.writeline("something 2"); this.postsomething2handler?.invoke(); this.presomething3handler?.invoke(); console.writeline("something 3"); this.postsomething3handler?.invoke(); this.presomething4handler?.invoke(); console.writeline("something 4"); this.postsomething4handler?.invoke(); this.presomething5handler?.invoke(); console.writeline("something 5"); this.postsomething5handler?.invoke(); this.presomething6handler?.invoke(); console.writeline("something 6"); this.postsomething6handler?.invoke(); this.endrequest?.invoke(); } //任何请求进来,只能是 123456 //事件升级后,可以在程序启动时,实例化httpapplicationdemo后,可以给事件注册动作,请求再进来时,处理不仅是123456了,还有多个事件里面的动作 }
对httpapplication里面的事件进行动作注册,就叫ihttpmodule。
自定义一个httpmodule+配置文件注册,然后任何一个请求都会执行init里面注册给application事件的动作。
public class customhttpmodule : ihttpmodule { public void dispose() { console.writeline(); } public event eventhandler customhttpmodulehandler; /// <summary> /// 注册动作 /// </summary> /// <param name="context"></param> public void init(httpapplication application) { application.beginrequest += (s, e) => { this.customhttpmodulehandler?.invoke(application, null); }; //application.endrequest += (s, e) => //{ // httpcontext.current.response.write("customhttpmodule.endrequest"); //}; #region 为每一个事件,都注册了一个动作,向客户端输出信息 application.acquirerequeststate += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "acquirerequeststate ")); application.authenticaterequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "authenticaterequest ")); application.authorizerequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "authorizerequest ")); application.beginrequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "beginrequest ")); application.disposed += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "disposed ")); application.endrequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "endrequest ")); application.error += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "error ")); application.logrequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "logrequest ")); application.maprequesthandler += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "maprequesthandler ")); application.postacquirerequeststate += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postacquirerequeststate ")); application.postauthenticaterequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postauthenticaterequest ")); application.postauthorizerequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postauthorizerequest ")); application.postlogrequest += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postlogrequest ")); application.postmaprequesthandler += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postmaprequesthandler ")); application.postreleaserequeststate += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postreleaserequeststate ")); application.postrequesthandlerexecute += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postrequesthandlerexecute ")); application.postresolverequestcache += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postresolverequestcache ")); application.postupdaterequestcache += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "postupdaterequestcache ")); application.prerequesthandlerexecute += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "prerequesthandlerexecute ")); application.presendrequestcontent += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "presendrequestcontent ")); application.presendrequestheaders += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "presendrequestheaders ")); application.releaserequeststate += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "releaserequeststate ")); application.requestcompleted += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "requestcompleted ")); application.resolverequestcache += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "resolverequestcache ")); application.updaterequestcache += (s, e) => application.response.write(string.format("<h1 style='color:#00f'>来自mycustommodule 的处理,{0}请求到达 {1}</h1><hr>", datetime.now.tostring(), "updaterequestcache ")); #endregion } }
访问下页面,就是这样的结果:
正常流程下,会按照顺序执行19个事件。
学完httpmodule,我们可以做点什么有用的扩展?
任何一个请求都会执行httpmoduleinit里面注册给application的事件
1、日志-性能监控
2、权限
3、缓存
4、页面加点东西
5、请求过滤
6、mvc就是一个module的扩展
不适合的:不是针对全部请求的,就不太适合用module,因为有性能损耗
1、多语言,根据cookie信息去查询不同的数据做不同的展示,如果是全部一套处理,最后httpmodule拦截+处理,适合httpmodule
2、跳转到不同界面,也不合适
3、防盗链,针对一类的后缀来处理的,而不是全部请求---判断----再防盗链
在httpmodule里面发布一个customhttpmodulehandler,在global增加一个动作customhttpmodulebingle_customhttpmodulehandler(配置文件module名称_module里面事件名称),请求响应时,该事件会执行
protected void customhttpmodulebingle_customhttpmodulehandler(object sender, eventargs e) { this.logger.info("this is customhttpmodulebingle_customhttpmodulehandler");
}
httpmodule是对httpapplication的事件动作注册动作,global是对httpmodule里面的事件注册动作。