我为Web API 2开发了自定义操作过滤器 - LogActionWebApiFilter ：
namespace Utility.Logger.WebApi.RequestResponse.Attributes
{
/// <summary>
/// Log action web API action filter
/// </summary>
internal class LogActionWebApiFilter : ActionFilterAttribute
{
#region Private Fields
/// <summary>
/// The current identifier
/// </summary>
private static Guid currentId;
/// <summary>
/// The request start time
/// </summary>
private static DateTime requestStartTime;
/// <summary>
/// The logger
/// </summary>
private IEventLogger logger;
#endregion Private Fields
#region Public Constructors
/// <summary>
/// Initializes a new instance of the <see cref="LogActionWebApiFilter"/> class.
/// </summary>
/// <param name="logger">The logger.</param>
public LogActionWebApiFilter(IEventLogger logger)
{
this.logger = logger;
}
#endregion Public Constructors
#region Public overrided Methods
/// <summary>
/// Occurs after the action method is invoked.
/// </summary>
/// <param name="actionExecutedContext">The action executed context.</param>
public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
if (actionExecutedContext.ActionContext.ActionDescriptor.GetCustomAttributes<NoLogWebApiFilter>().Any())
{
return;
}
// Some business logic
this.logger.DebugFormat("API Call of {0}()", actionExecutedContext.ActionContext.ActionDescriptor.ActionName);
}
/// <summary>
/// Occurs before the action method is invoked.
/// </summary>
/// <param name="actionContext">The action context.</param>
public override void OnActionExecuting(HttpActionContext actionContext)
{
if (actionContext.ActionDescriptor.GetCustomAttributes<NoLogWebApiFilter>().Any())
{
return;
}
// Some business logic
}
#endregion Public overrided Methods
}
}
现在，我希望在应用程序启动后根据标志注册/取消注册此自定义操作过滤器运行时。
这是我的过滤器注册码：
public void StartLogging()
{
var existingFilter
= System.Web.Http.GlobalConfiguration.Configuration.Filters.FirstOrDefault(
f =>
f.Instance.GetType().ToString().Equals(typeof(LogActionWebApiFilter).ToString()
));
if (existingFilter == null)
{
System.Web.Http.GlobalConfiguration.Configuration.Filters.Add(new LogActionWebApiFilter(this.logger));
}
}
这是我的过滤器注销代码：
public void StopLogging()
{
var existingFilter
= System.Web.Http.GlobalConfiguration.Configuration.Filters.FirstOrDefault(
f =>
f.Instance.GetType().ToString().Equals(typeof(LogActionWebApiFilter).ToString()
));
if (existingFilter != null)
{
System.Web.Http.GlobalConfiguration.Configuration.Filters.Remove(existingFilter.Instance);
existingFilter = null;
}
}
问题： -
Application_BeginRequest() - 事件中，我检查标志（有一些业务逻辑），并根据标志的值我从上述两种方法中调用相应的方法。System.Web.Http.GlobalConfiguration.Configuration.Filters，但OnActionExecuting() / OnActionExecuted()中的任何一个都未被调用。请指导我，我在这里做错了什么。
提前致谢， Balaguru。
答案 0 :(得分：0)
无法在Application_BeginRequest（）事件中控制动作过滤器。动作过滤器是全局过滤器，只能在Application_Start（）中注册。
我建议你可以通过配置文件添加或删除过滤器。
<configSections>
<section name="filters" type="ConfigurableFilters.FiltersSettings, AssemblyName "/>
</configSections>
<filters>
<add type="ConfigurableFilters.BarFilter, AssemblyName" />
<add type="ConfigurableFilters.FooFilter, AssemblyName" />
</filters>
在这种情况下，您需要一个ConfigurationElement。
Public class FilterAction : ConfigurationElement
{
[ConfigurationProperty("type", IsRequired = true, IsKey = true)]
public string Type
{
get { return base["type"] as string; }
set { base["type"] = value; }
}
}
还有一个ConfigurationElementCollection。
public class FilterActionCollection : ConfigurationElementCollection
{
protected override ConfigurationElement CreateNewElement()
{ return new FilterAction();}
protected override object GetElementKey(ConfigurationElement element)
{ return ((FilterAction) element).Type;}
}
还有一个ConfigurationSection。
public class FiltersSettings : ConfigurationSection
{
public static FiltersSettings Settings
{
get {
var section = ConfigurationManager.GetSection("filters")
as FiltersSettings;
return section ?? new FiltersSettings();
}
}
[ConfigurationProperty("", IsDefaultCollection = true)]
public FilterActionCollection Filters
{
get { return base[_filtersProperty] as FilterActionCollection; }
set { base[_filtersProperty] = value; }
}
private readonly ConfigurationProperty _filtersProperty =
new ConfigurationProperty(
null, typeof (FilterActionCollection), null,
ConfigurationPropertyOptions.IsDefaultCollection);
}
应用已配置过滤器的一种方法是在应用程序启动期间使用以下代码：
var filters = FiltersSettings.Settings.Filters;
foreach (var filter in filters.Cast<FilterAction>())
{
var filterType = Type.GetType(filter.Type);
GlobalFilters.Filters.Add(Activator.CreateInstance(filterType));
}
答案 1 :(得分：0)
这里最简单的答案是将一个切换值添加到/* Smartphones (portrait and landscape) ----------- */
@media only screen and (min-device-width : 320px) and (max-device-width : 480px) {
/* Styles */
}
/* Smartphones (landscape) ----------- */
@media only screen and (min-width : 321px) {
/* Styles */
}
/* Smartphones (portrait) ----------- */
@media only screen and (max-width : 320px) {
/* Styles */
}
/* iPads (portrait and landscape) ----------- */
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) {
/* Styles */
}
/* iPads (landscape) ----------- */
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) {
/* Styles */
}
/* iPads (portrait) ----------- */
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) {
/* Styles */
}
/**********
iPad 3
**********/
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
/* Desktops and laptops ----------- */
@media only screen and (min-width : 1224px) {
/* Styles */
}
/* Large screens ----------- */
@media only screen and (min-width : 1824px) {
/* Styles */
}
/* iPhone 4 ----------- */
@media only screen and (min-device-width : 320px) and (max-device-width : 480px) and (orientation : landscape) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
@media only screen and (min-device-width : 320px) and (max-device-width : 480px) and (orientation : portrait) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
/* iPhone 5 ----------- */
@media only screen and (min-device-width: 320px) and (max-device-height: 568px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
@media only screen and (min-device-width: 320px) and (max-device-height: 568px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
/* iPhone 6 ----------- */
@media only screen and (min-device-width: 375px) and (max-device-height: 667px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
@media only screen and (min-device-width: 375px) and (max-device-height: 667px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
/* iPhone 6+ ----------- */
@media only screen and (min-device-width: 414px) and (max-device-height: 736px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
@media only screen and (min-device-width: 414px) and (max-device-height: 736px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
/* Samsung Galaxy S3 ----------- */
@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */
}
/* Samsung Galaxy S4 ----------- */
@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 3){
/* Styles */
}
@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 3){
/* Styles */
}
/* Samsung Galaxy S5 ----------- */
@media only screen and (min-device-width: 360px) and (max-device-height: 640px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 3){
/* Styles */
}
@media only screen and (min-device-width: 360px) and (max-device-height: 640px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 3){
/* Styles */
}并在您的日志记录代码中查询。
Request.Properties在您的记录器中：
public void StartLogging()
{
// Check the value does not already exist etc. and either add or modify.
if (actionContext.Request.Properties.ContainsKey("ShouldLog")) {
actionContext.Request.Properties["ShouldLog"] = true;
}
else {
actionContext.Request.Properties.Add("ShouldLog", true);
}
}