Microsoft.Practices.ServiceLocation 之 动态单例模式
背景
框架开发中，经常会用到“单例模式”，但是传统的单例模式不支持多态和运行时变化，在关注测试的今天，这种模式是不可行的。为了应对这种情况，微软又提供了另外一种模式，暂且将其称为“动态单例模式”。 我也想统一我的框架对单例的使用模式，因此就写了这篇文章。
Microsoft.Practices.ServiceLocation 核心代码
看完代码，如何使用这种模式就不用我多介绍了。
IServiceLocator
View Code1 using System; 2 using System.Collections.Generic; 3 4 namespace Microsoft.Practices.ServiceLocation 5 { 6 /// <summary> 7 /// The generic Service Locator interface. This interface is used 8 /// to retrieve services (instances identified by type and optional 9 /// name) from a container. 10 /// </summary> 11 public interface IServiceLocator : IServiceProvider 12 { 13 /// <summary> 14 /// Get an instance of the given <paramref name="serviceType"/>. 15 /// </summary> 16 /// <param name="serviceType">Type of object requested.</param> 17 /// <exception cref="ActivationException">if there is an error resolving 18 /// the service instance.</exception> 19 /// <returns>The requested service instance.</returns> 20 object GetInstance(Type serviceType); 21 22 /// <summary> 23 /// Get an instance of the given named <paramref name="serviceType"/>. 24 /// </summary> 25 /// <param name="serviceType">Type of object requested.</param> 26 /// <param name="key">Name the object was registered with.</param> 27 /// <exception cref="ActivationException">if there is an error resolving 28 /// the service instance.</exception> 29 /// <returns>The requested service instance.</returns> 30 object GetInstance(Type serviceType, string key); 31 32 /// <summary> 33 /// Get all instances of the given <paramref name="serviceType"/> currently 34 /// registered in the container. 35 /// </summary> 36 /// <param name="serviceType">Type of object requested.</param> 37 /// <exception cref="ActivationException">if there is are errors resolving 38 /// the service instance.</exception> 39 /// <returns>A sequence of instances of the requested <paramref name="serviceType"/>.</returns> 40 IEnumerable<object> GetAllInstances(Type serviceType); 41 42 /// <summary> 43 /// Get an instance of the given <typeparamref name="TService"/>. 44 /// </summary> 45 /// <typeparam name="TService">Type of object requested.</typeparam> 46 /// <exception cref="ActivationException">if there is are errors resolving 47 /// the service instance.</exception> 48 /// <returns>The requested service instance.</returns> 49 TService GetInstance<TService>(); 50 51 /// <summary> 52 /// Get an instance of the given named <typeparamref name="TService"/>. 53 /// </summary> 54 /// <typeparam name="TService">Type of object requested.</typeparam> 55 /// <param name="key">Name the object was registered with.</param> 56 /// <exception cref="ActivationException">if there is are errors resolving 57 /// the service instance.</exception> 58 /// <returns>The requested service instance.</returns> 59 TService GetInstance<TService>(string key); 60 61 /// <summary> 62 /// Get all instances of the given <typeparamref name="TService"/> currently 63 /// registered in the container. 64 /// </summary> 65 /// <typeparam name="TService">Type of object requested.</typeparam> 66 /// <exception cref="ActivationException">if there is are errors resolving 67 /// the service instance.</exception> 68 /// <returns>A sequence of instances of the requested <typeparamref name="TService"/>.</returns> 69 IEnumerable<TService> GetAllInstances<TService>(); 70 } 71 }
ServiceLocatorProvider
View Code1 namespace Microsoft.Practices.ServiceLocation 2 { 3 /// <summary> 4 /// This delegate type is used to provide a method that will 5 /// return the current container. Used with the <see cref="ServiceLocator"/> 6 /// static accessor class. 7 /// </summary> 8 /// <returns>An <see cref="IServiceLocator"/>.</returns> 9 public delegate IServiceLocator ServiceLocatorProvider(); 10 }
ServiceLocator
View Code1 namespace Microsoft.Practices.ServiceLocation 2 { 3 /// <summary> 4 /// This class provides the ambient container for this application. If your 5 /// framework defines such an ambient container, use ServiceLocator.Current 6 /// to get it. 7 /// </summary> 8 public static class ServiceLocator 9 { 10 private static ServiceLocatorProvider currentProvider; 11 12 /// <summary> 13 /// The current ambient container. 14 /// </summary> 15 public static IServiceLocator Current 16 { 17 get { return currentProvider(); } 18 } 19 20 /// <summary> 21 /// Set the delegate that is used to retrieve the current container. 22 /// </summary> 23 /// <param name="newProvider">Delegate that, when called, will return 24 /// the current ambient container.</param> 25 public static void SetLocatorProvider(ServiceLocatorProvider newProvider) 26 { 27 currentProvider = newProvider; 28 } 29 } 30 }
动态单例模式的优点
- 支持多态。
- 运行时可变。
- 支持其它级别范围的单例，如：请求级、线程级和会话级等。
- 支持对象池。
纯CSS3实现手风琴风格菜单
今天分享一个如何使用纯CSS3创建手风琴风格菜单教程，菜单主要通过使用:target伪类来实现。
:target使用介绍
CSS3 target伪类是众多实用的CSS3特性中的一个。它用来匹配文档(页面)的URI中某个标志符的目标元素。具体来说，URI中的标志符通常会包含一 个”#”字符，然后后面带有一个标志符名称，比如#respond，target就是用来匹配ID为respond的元素的。
现在在页面中，点击一个ID链接后，页面只会跳转到相应的位置，但是并不会有比较明显的UI标识，使用:target伪类可以像:hover等伪类一样对目标元素定义样式。第一步：HTML标签结构
一 个简单的无序列表，每个li中包含一个超链接和span，同时为每一个li添加一个不同的id和一个连接到这个id的超链接。为了添加样式和展开菜单项下 面的内容，需要使用:target伪类。
1 <ul class="accordion"> 2 3 <li id="one" class="files"><a href="#one">我的文件<span>495</span></a></li> 4 5 <li id="two" class="mail"><a href="#two">邮件<span>26</span></a></li> 6 7 <li id="three" class="cloud"><a href="#three">网盘<span>58</span></a></li> 8 9 <li id="four" class="sign"><a href="#four">退出登录</a></li> 10 11 </ul>
第二步：菜单布局基本样式
首先修改一些浏览器默认 样式，清除margin padding等等。
1 .accordion, 2 .accordion ul, 3 .accordion li, 4 .accordion a, 5 .accordion span { 6 margin: 0; 7 padding: 0; 8 border: none; 9 outline: none; 10 text-align:left; 11 } 12 13 .accordion li { 14 list-style: none; 15 }
定义菜单项链接样式，添加渐变，阴影的效果，定义字体等。这里没有指定固定的宽度，菜单的 宽度100%填充它的父元素，如果你想把菜单设置成300px，你可以给它添加一个父div，指定宽度为300px就可以了。虽然没有指定宽度，但是定义 了最小宽度，保证菜单布局能够正确的显示。
1 .accordion li > a { 2 display: block; 3 position: relative; 4 min-width: 110px; 5 padding: 0 10px 0 40px; 6 7 color: #fdfdfd; 8 font: bold 14px/32px 黑体,宋体; 9 text-decoration: none; 10 text-shadow: 0px 1px 0px rgba(0,0,0, .35); 11 12 background: #6c6e74; 13 background: -moz-linear-gradient(top, #6c6e74 0%, #4b4d51 100%); 14 background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#6c6e74), color-stop(100%,#4b4d51)); 15 background: -webkit-linear-gradient(top, #6c6e74 0%,#4b4d51 100%); 16 background: -o-linear-gradient(top, #6c6e74 0%,#4b4d51 100%); 17 background: -ms-linear-gradient(top, #6c6e74 0%,#4b4d51 100%); 18 background: linear-gradient(top, #6c6e74 0%,#4b4d51 100%); 19 20 -webkit-box-shadow: inset 0px 1px 0px 0px rgba(255,255,255, .1), 0px 1px 0px 0px rgba(0,0,0, .1); 21 -moz-box-shadow: inset 0px 1px 0px 0px rgba(255,255,255, .1), 0px 1px 0px 0px rgba(0,0,0, .1); 22 box-shadow: inset 0px 1px 0px 0px rgba(255,255,255, .1), 0px 1px 0px 0px rgba(0,0,0, .1); 23 }
定义数字指示器样式，当然如果你的菜单不需要数字指示器，你打可以删掉这个html结构中 span元素。
1 .accordion li > a span { 2 display: block; 3 position: absolute; 4 top: 7px; 5 right: 0; 6 padding: 0 10px; 7 margin-right: 10px; 8 9 font: normal bold 12px/18px Arial, sans-serif; 10 background: #404247; 11 12 -webkit-border-radius: 15px; 13 -moz-border-radius: 15px; 14 border-radius: 15px; 15 16 -webkit-box-shadow: inset 1px 1px 1px rgba(0,0,0, .2), 1px 1px 1px rgba(255,255,255, .1); 17 -moz-box-shadow: inset 1px 1px 1px rgba(0,0,0, .2), 1px 1px 1px rgba(255,255,255, .1); 18 box-shadow: inset 1px 1px 1px rgba(0,0,0, .2), 1px 1px 1px rgba(255,255,255, .1); 19 }
第三步：添加图标样式
我们使用:before为菜单插入图标，图标的宽 高都是24px，用下面的样式使其正确的显示。我创建了一个sprite，包含了四个图标的正常和hover时候的不同样式。
1 .accordion > li > a:before { 2 position: absolute; 3 top: 0; 4 left: 0; 5 content: ''; 6 width: 24px; 7 height: 24px; 8 margin: 4px 8px; 9 10 background-repeat: no-repeat; 11 background-image: url(../images/icons.png); 12 background-position: 0px 0px; 13 } 14 15 .accordion li.files > a:before { background-position: 0px 0px; } 16 .accordion li.files:hover > a:before, 17 .accordion li.files:target > a:before { background-position: 0px -24px; } 18 19 .accordion li.mail > a:before { background-position: -24px 0px; } 20 .accordion li.mail:hover > a:before, 21 .accordion li.mail:target > a:before { background-position: -24px -24px; } 22 23 .accordion li.cloud > a:before { background-position: -48px 0px; } 24 .accordion li.cloud:hover > a:before, 25 .accordion li.cloud:target > a:before { background-position: -48px -24px; } 26 27 .accordion li.sign > a:before { background-position: -72px 0px; } 28 .accordion li.sign:hover > a:before, 29 .accordion li.sign:target > a:before { background-position: -72px -24px; }
第四步：子菜单HTML和样式
HTML：
同 样也使用ul作为子菜单，放到父菜单的li里面，如下代码：
1 <li id="one"><a href="#one">我的文件<span>495</span></a> 2 <ul> 3 4 <li><a href="javascript:void(0);"><em>01</em>音乐<span>42</span></a></li> 5 6 <li><a href="javascript:void(0);"><em>02</em>视频<span>87</span></a></li> 7 8 <li><a href="javascript:void(0);"><em>03</em>图片<span>366</span></a></li> 9 </ul> 10 11 </li>
CSS：
1 .sub-menu li a { 2 font: bold 12px/32px 黑体,宋体; 3 color: #797979; 4 text-shadow: 1px 1px 0px rgba(255,255,255, .2); 5 6 background: #e5e5e5; 7 border-bottom: 1px solid #c9c9c9; 8 9 -webkit-box-shadow: inset 0px 1px 0px 0px rgba(255,255,255, .1), 0px 1px 0px 0px rgba(0,0,0, .1); 10 -moz-box-shadow: inset 0px 1px 0px 0px rgba(255,255,255, .1), 0px 1px 0px 0px rgba(0,0,0, .1); 11 box-shadow: inset 0px 1px 0px 0px rgba(255,255,255, .1), 0px 1px 0px 0px rgba(0,0,0, .1); 12 } 13 14 .sub-menu li:last-child a { border: none; } 15 16 .sub-menu li > a span { 17 color: #797979; 18 text-shadow: 1px 1px 0px rgba(255,255,255, .2); 19 background: transparent; 20 border: 1px solid #c9c9c9; 21 22 -webkit-box-shadow: none; 23 -moz-box-shadow: none; 24 box-shadow: none; 25 } 26 27 .sub-menu em { 28 position: absolute; 29 top: 0; 30 left: 0; 31 margin-left: 14px; 32 color: #a6a6a6; 33 font: normal 10px/32px Arial, sans-serif; 34 }
第五步：定义鼠标悬浮和菜单激活时状态样式
当鼠标悬浮和菜单激活时改变 背景为绿色。
1 .accordion > li:hover > a, 2 .accordion > li:target > a { 3 color: #3e5706; 4 text-shadow: 1px 1px 1px rgba(255,255,255, .2); 5 background: #a5cd4e; 6 background: -moz-linear-gradient(top, #a5cd4e 0%, #6b8f1a 100%); 7 background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#a5cd4e), color-stop(100%,#6b8f1a)); 8 background: -webkit-linear-gradient(top, #a5cd4e 0%,#6b8f1a 100%); 9 background: -o-linear-gradient(top, #a5cd4e 0%,#6b8f1a 100%); 10 background: -ms-linear-gradient(top, #a5cd4e 0%,#6b8f1a 100%); 11 background: linear-gradient(top, #a5cd4e 0%,#6b8f1a 100%); 12 } 13 14 .accordion > li:hover > a span, 15 .accordion > li:target > a span { 16 color: #fdfdfd; 17 text-shadow: 0px 1px 0px rgba(0,0,0, .35); 18 background: #3e5706; 19 } 20 21 .sub-menu li:hover a { background: #efefef; }
第六步：控制子菜单的显示与隐藏
为 了隐藏子菜单，我们需要定义子菜单的高度为0px。当点击父菜单时，为子菜单添加下滑显示的动态效果。为了实现下滑的效果，需要指定子菜单固定的高度。因 为这个教程中子菜单有三个link，所以这里指定了98px。如果你想加更多的子菜单就需要修改height为所有子菜单的高度和，当然如果你想要让它自 动变化，可以给高度赋值100%，但是这样下滑的动画效果就没有了。
1 .accordion li > .sub-menu { 2 height: 0; 3 overflow: hidden; 4 5 -webkit-transition: all .2s ease-in-out; 6 -moz-transition: all .2s ease-in-out; 7 -o-transition: all .2s ease-in-out; 8 -ms-transition: all .2s ease-in-out; 9 transition: all .2s ease-in-out; 10 } 11 12 .accordion li:target > .sub-menu { 13 height: 98px; 14 }
总结：
到此纯CSS3实现的手风琴风格菜单就全部结束了。教程中我们主要通过使用伪类:before和:target来定义样式，使用:target来实现菜单点击展开子菜单事件。希望你能够喜欢这个教程。
分类: CSS3