网站就必须用响应式布局吗？MVC视图展现模式之移动布局：

demo:

有人会疑问，为什么他能识别.mobile的后缀却不能识别例如：.mac .dnt 等等后缀呢？这些又是放在哪里的呢？

mobile 这个后缀其实是存放在：DisplayModeProvider.Instance.Modes 里面的，我们监视一下，发现里面就一个mobile，还有一个是默认的

可以猜想，运行的时候是从上往下匹配的，“”的是通用匹配，那么我们加入一个自定义的后缀看看==>(可以思考一下，为什么用 insert 不用 add)

//添加一个自定义后缀            DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("dnt")            {                ContextCondition = (Context) => Context.Request.UserAgent.Contains("dnt")            });

可能你不是很理解 DefaultDisplayMode，看看反编译吧----构造函数为suffix赋值（后缀）

添加一个自定义的后缀视图

打开谷歌浏览器，设置一下User-Agent Switcher的浏览模式

附录：

DisplayModeProvider：

// Generated by .NET Reflector from F:\Work\Net\Mobile\packages\Microsoft.AspNet.WebPages.3.2.3\lib\net45\System.Web.WebPages.dllnamespace System.Web.WebPages{    using System;    using System.Collections;    using System.Collections.Generic;    using System.Diagnostics;    using System.Runtime.CompilerServices;    using System.Web;        public sealed class DisplayModeProvider    {        private static readonly object _displayModeKey = new object();        private readonly List
      
        _displayModes;        private static readonly DisplayModeProvider _instance = new DisplayModeProvider();        public static readonly string DefaultDisplayModeId = string.Empty;        public static readonly string MobileDisplayModeId = "Mobile";                internal DisplayModeProvider()        {            List
       
         list = new List
        
         ();            DefaultDisplayMode item = new DefaultDisplayMode(MobileDisplayModeId) {                ContextCondition = context => context.GetOverriddenBrowser().IsMobileDevice            };            list.Add(item);            list.Add(new DefaultDisplayMode());            this._displayModes = list;        }                private int FindFirstAvailableDisplayMode(IDisplayMode currentDisplayMode, bool requireConsistentDisplayMode)        {            if (!requireConsistentDisplayMode || (currentDisplayMode == null))            {                return 0;            }            int index = this._displayModes.IndexOf(currentDisplayMode);            if (index < 0)            {                return this._displayModes.Count;            }            return index;        }                public IEnumerable
         
           GetAvailableDisplayModesForContext(HttpContextBase httpContext, IDisplayMode currentDisplayMode)        {            return this.GetAvailableDisplayModesForContext(httpContext, currentDisplayMode, this.RequireConsistentDisplayMode);        }                internal IEnumerable
          
            GetAvailableDisplayModesForContext(HttpContextBase httpContext, IDisplayMode currentDisplayMode, bool requireConsistentDisplayMode)        {            int iteratorVariable0 = this.FindFirstAvailableDisplayMode(currentDisplayMode, requireConsistentDisplayMode);            for (int i = iteratorVariable0; i < this._displayModes.Count; i++)            {                IDisplayMode iteratorVariable2 = this._displayModes[i];                if (iteratorVariable2.CanHandleContext(httpContext))                {                    yield return iteratorVariable2;                }            }        }                public DisplayInfo GetDisplayInfoForVirtualPath(string virtualPath, HttpContextBase httpContext, Func
           
             virtualPathExists, IDisplayMode currentDisplayMode) { return this.GetDisplayInfoForVirtualPath(virtualPath, httpContext, virtualPathExists, currentDisplayMode, this.RequireConsistentDisplayMode); } internal DisplayInfo GetDisplayInfoForVirtualPath(string virtualPath, HttpContextBase httpContext, Func
            
              virtualPathExists, IDisplayMode currentDisplayMode, bool requireConsistentDisplayMode) { for (int i = this.FindFirstAvailableDisplayMode(currentDisplayMode, requireConsistentDisplayMode); i < this._displayModes.Count; i++) { IDisplayMode mode = this._displayModes[i]; if (mode.CanHandleContext(httpContext)) { DisplayInfo info = mode.GetDisplayInfo(httpContext, virtualPath, virtualPathExists); if (info != null) { return info; } } } return null; } internal static IDisplayMode GetDisplayMode(HttpContextBase context) { if (context == null) { return null; } return (context.Items[_displayModeKey] as IDisplayMode); } internal static void SetDisplayMode(HttpContextBase context, IDisplayMode displayMode) { if (context != null) { context.Items[_displayModeKey] = displayMode; } } public static DisplayModeProvider Instance { get { return _instance; } } public IList
             
               Modes { get { return this._displayModes; } } public bool RequireConsistentDisplayMode { get; set; } [CompilerGenerated] private sealed class 
              
               d__4 : IEnumerable
               
                , IEnumerable, IEnumerator
                
                 , IEnumerator, IDisposable { private int <>1__state; private IDisplayMode <>2__current; public IDisplayMode <>3__currentDisplayMode; public HttpContextBase <>3__httpContext; public bool <>3__requireConsistentDisplayMode; public DisplayModeProvider <>4__this; private int <>l__initialThreadId; public int 
                 
                  5__5; public int 
                  5__6; public IDisplayMode 
                   
                    5__7; public IDisplayMode currentDisplayMode; public HttpContextBase httpContext; public bool requireConsistentDisplayMode; [DebuggerHidden] public 
                    
                     d__4(int <>1__state) { this.<>1__state = <>1__state; this.<>l__initialThreadId = Environment.CurrentManagedThreadId; } private bool MoveNext() { switch (this.<>1__state) { case 0: this.<>1__state = -1; this.
                     
                      5__5 = this.<>4__this.FindFirstAvailableDisplayMode(this.currentDisplayMode, this.requireConsistentDisplayMode); this.
                      5__6 = this.
                       
                        5__5; goto Label_00A5; case 1: this.<>1__state = -1; break; default: goto Label_00BD; } Label_0097: this.
                        5__6++; Label_00A5: if (this.5__6 < this.<>4__this._displayModes.Count) { this.
                          
                           5__7 = this.<>4__this._displayModes[this.
                           5__6]; if (this.
                            
                             5__7.CanHandleContext(this.httpContext)) { this.<>2__current = this.
                             
                              5__7; this.<>1__state = 1; return true; } goto Label_0097; } Label_00BD: return false; } [DebuggerHidden] IEnumerator
                              
                                IEnumerable
                               
                                .GetEnumerator() { DisplayModeProvider.
                                
                                 d__4 d__; if ((Environment.CurrentManagedThreadId == this.<>l__initialThreadId) && (this.<>1__state == -2)) { this.<>1__state = 0; d__ = this; } else { d__ = new DisplayModeProvider.
                                 
                                  d__4(0) { <>4__this = this.<>4__this }; } d__.httpContext = this.<>3__httpContext; d__.currentDisplayMode = this.<>3__currentDisplayMode; d__.requireConsistentDisplayMode = this.<>3__requireConsistentDisplayMode; return d__; } [DebuggerHidden] IEnumerator IEnumerable.GetEnumerator() { return this.System.Collections.Generic.IEnumerable
                                  
                                   .GetEnumerator(); } [DebuggerHidden] void IEnumerator.Reset() { throw new NotSupportedException(); } void IDisposable.Dispose() { } IDisplayMode IEnumerator
                                   
                                    .Current { [DebuggerHidden] get { return this.<>2__current; } } object IEnumerator.Current { [DebuggerHidden] get { return this.<>2__current; } } } }}
                                   
                                  
                                 
                                
                               
                              
                             
                            
                          
                       
                     
                    
                   
                 
                
               
              
             
            
           
          
         
        
       
      

DefaultDisplayMode：

// Generated by .NET Reflector from F:\Work\Net\Mobile\packages\Microsoft.AspNet.WebPages.3.2.3\lib\net45\System.Web.WebPages.dllnamespace System.Web.WebPages{    using System;    using System.IO;    using System.Runtime.CompilerServices;    using System.Web;        public class DefaultDisplayMode : IDisplayMode    {        private readonly string _suffix;                public DefaultDisplayMode() : this(DisplayModeProvider.DefaultDisplayModeId)        {        }                public DefaultDisplayMode(string suffix)        {            this._suffix = suffix ?? string.Empty;        }                public bool CanHandleContext(HttpContextBase httpContext)        {            if (this.ContextCondition != null)            {                return this.ContextCondition(httpContext);            }            return true;        }                public virtual DisplayInfo GetDisplayInfo(HttpContextBase httpContext, string virtualPath, Func
      
        virtualPathExists)        {            string arg = this.TransformPath(virtualPath, this._suffix);            if ((arg != null) && virtualPathExists(arg))            {                return new DisplayInfo(arg, this);            }            return null;        }                protected virtual string TransformPath(string virtualPath, string suffix)        {            if (string.IsNullOrEmpty(suffix))            {                return virtualPath;            }            string extension = Path.GetExtension(virtualPath);            return Path.ChangeExtension(virtualPath, suffix + extension);        }                public Func
       
         ContextCondition { get; set; }                public virtual string DisplayModeId        {            get            {                return this._suffix;            }        }    }}
       
      

参考：