在.net framework mvc 中有四种过滤器，授权过滤器（authorize）、action 过滤器、结果过滤器（result）、异常过滤器（exception）四种过滤器。在.net core mvc中，有五种过滤器，授权过滤器、action过滤器、异常过滤器、结果过滤器、资源过滤器，新增了资源过滤器。
.net core mvc和.net framework mvc在基本使用上差别不大，主要的还是框架的差别。其中路由是个很重要的东西，参考文章：
action过滤器、结果过滤器、exception，三个特性，没有什么变化。在exceptionfilter多了个order参数，就是用来排序的。
结果过滤器，包装了单个action result的执行，当且晋档action方法成功执行完毕后才运行。它们是理想的围绕视图执行或格式处理的逻辑（所在之处）。继承attribute，iresultfilter
/// <summary>
/// result的filter
/// </summary>
public class customresultfilterattribute : attribute, iresultfilter
{
//private logger logger = logger.createlogger(typeof(customresultfilterattribute));
public void onresultexecuted(resultexecutedcontext context)
{
console.writeline("onresultexecuted executed!");
//logger.info("onresultexecuted executed!");
}
public void onresultexecuting(resultexecutingcontext context)
{
console.writeline("onresultexecuting executing!");
//logger.info("onresultexecuting executing!");
}
}
异常过滤器，为mvc隐藏程序为处理异常应用全局策略。继承exceptionfilterattribute
/// <summary>
/// 异常处理的filter
/// </summary>
public class customexceptionfilterattribute : exceptionfilterattribute
{
private readonly ihostingenvironment _hostingenvironment;
private readonly imodelmetadataprovider _modelmetadataprovider;
//private logger logger = logger.createlogger(typeof(customexceptionfilterattribute));
/// <summary>
/// ioc来的
/// </summary>
/// <param name="hostingenvironment"></param>
/// <param name="modelmetadataprovider"></param>
public customexceptionfilterattribute(
ihostingenvironment hostingenvironment,
imodelmetadataprovider modelmetadataprovider)
{
_hostingenvironment = hostingenvironment;
_modelmetadataprovider = modelmetadataprovider;
}
/// <summary>
/// 没有处理的异常，就会进来
/// </summary>
/// <param name="filtercontext"></param>
public override void onexception(exceptioncontext filtercontext)
{
if (!filtercontext.exceptionhandled)//异常有没有被处理过
{
string controllername = (string)filtercontext.routedata.values["controller"];
string actionname = (string)filtercontext.routedata.values["action"];
string msgtemplate = "在执行 controller[{0}] 的 action[{1}] 时产生异常";
//logger.error(string.format(msgtemplate, controllername, actionname), filtercontext.exception);
if (this.isajaxrequest(filtercontext.httpcontext.request))//检查请求头
{
filtercontext.result = new jsonresult(
new
{
result = false,
promptmsg = "系统出现异常，请联系管理员",
debugmessage = filtercontext.exception.message
}//这个就是返回的结果
);
}
else
{
var result = new viewresult { viewname = "~/views/shared/error.cshtml" };
result.viewdata = new viewdatadictionary(_modelmetadataprovider, filtercontext.modelstate);
result.viewdata.add("exception", filtercontext.exception);
filtercontext.result = result;
}
filtercontext.exceptionhandled = true;
}
}
private bool isajaxrequest(httprequest request)
{
string header = request.headers["x-requested-with"];
return "xmlhttprequest".equals(header);
}
}
定义完exceptionfilter，该怎么注册到全局呢？在stratup.cs中configureserver中，进行注册
services.addmvc(o =>
{
o.filters.add(typeof(customexceptionfilterattribute));// 这里就是全局注册filter
}).setcompatibilityversion(compatibilityversion.version_2_2);
action 过滤器，包装了对单个action方法的调用，可以将参数传递给action并从中获得action result。继承iactionfilter
/// <summary>
/// action的filter`
/// </summary>
public class customactionfilterattribute : attribute, iactionfilter
{
private ilogger<customactionfilterattribute> _logger = null;
public customactionfilterattribute(ilogger<customactionfilterattribute> logger)
{
this._logger = logger;
}
public void onactionexecuted(actionexecutedcontext context)
{
//context.httpcontext.response.writeasync("actionfilter executed!");
console.writeline("actionfilter executed!");
//this._logger.logdebug("actionfilter executed!");
}
public void onactionexecuting(actionexecutingcontext context)
{
//context.httpcontext.response.writeasync("actionfilter executing!");
console.writeline("actionfilter executing!");
//this._logger.logdebug("actionfilter executing!");
}
}
在startup.cs中configureservices进行注册
//允许使用servicefilter 标记特性 services.addscoped<customactionfilterattribute>();
标记到controller的actionfilter
/// <summary>
/// 标记到controller
/// </summary>
public class customcontrolleractionfilterattribute : attribute, iactionfilter
{
private ilogger<customcontrolleractionfilterattribute> _logger = null;
public customcontrolleractionfilterattribute(ilogger<customcontrolleractionfilterattribute> logger)
{
this._logger = logger;
}
public void onactionexecuted(actionexecutedcontext context)
{
//context.httpcontext.response.writeasync("actionfilter executed!");
console.writeline("actionfilter executed!");
//this._logger.logdebug("actionfilter executed!");
}
public void onactionexecuting(actionexecutingcontext context)
{
//context.httpcontext.response.writeasync("actionfilter executing!");
console.writeline("actionfilter executing!");
//this._logger.logdebug("actionfilter executing!");
}
}
[typefilter(typeof(customcontrolleractionfilterattribute),order =-1)]
public class thirdcontroller : controller
{
}
注册到全局的actionfilter
public class customglobalactionfilterattribute : attribute, iactionfilter
{
private ilogger<customglobalactionfilterattribute> _logger = null;
public customglobalactionfilterattribute(ilogger<customglobalactionfilterattribute> logger)
{
this._logger = logger;
}
public void onactionexecuted(actionexecutedcontext context)
{
//context.httpcontext.response.writeasync("actionfilter executed!");
console.writeline("actionfilter executed!");
//this._logger.logdebug("actionfilter executed!");
}
public void onactionexecuting(actionexecutingcontext context)
{
//context.httpcontext.response.writeasync("actionfilter executing!");
console.writeline("actionfilter executing!");
//this._logger.logdebug("actionfilter executing!");
}
}
还是要在startup中进行全局的注册
services.addmvc(o =>
{
o.filters.add(typeof(customglobalactionfilterattribute));// 这里就是全局注册filter
}).setcompatibilityversion(compatibilityversion.version_2_2);
分别对全局、控制器、action注册了actionfilter默认执行顺序：
全局onactionexecuting===》控制器的onactionexecuting====》action的onactionexecuting====》执行action ====》action的onactionexecuted====》控制器的onactionexecuted====》全局的onactionexecuted。类似于一个俄罗斯套娃，也可以说是一个洋葱模型。
资源过滤器，是授权之后第一个用来处理请求的过滤器，也是最后一个接触到请求的过滤器（因为之后就会离开过滤器管道）。在性能方面，资源过滤器在实现缓存或短路过滤器管道尤其有用。继承iresourcefilter
/// <summary>
/// 自定义的资源filter
/// </summary>
public class customresourcefilterattribute : attribute, iresourcefilter
{
private static readonly dictionary<string, object> _cache = new dictionary<string, object>();
private string _cachekey;
/// <summary>
/// 控制器实例化之前
/// </summary>
/// <param name="context"></param>
public void onresourceexecuting(resourceexecutingcontext context)
{
_cachekey = context.httpcontext.request.path.tostring();
if (_cache.containskey(_cachekey))
{
var cachedvalue = _cache[_cachekey] as viewresult;
if (cachedvalue != null)
{
context.result = cachedvalue;
}
}
}
/// <summary>
/// 把请求都处理完的
/// </summary>
/// <param name="context"></param>
public void onresourceexecuted(resourceexecutedcontext context)
{
if (!string.isnullorempty(_cachekey) &&
!_cache.containskey(_cachekey))
{
var result = context.result as viewresult;
if (result != null)
{
_cache.add(_cachekey, result);
}
}
}
}
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