深入理解BootStrap 缩略图（thumbnail）与警示窗（alert）13

1、缩略图

缩略图在网站中最常用的地方就是产品列表页面，一行显示几张图片，有的在图片底下（左侧或右侧）带有标题、描述等信息。Bootstrap框架将这一部独立成一个模块组件。并通过“thumbnail”样式配合bootstrap的网格系统来实现。可以将产品列表页变得更好看。

源码文件：

☑ LESS版本：对应文件thumbnails.less

☑ Sass版本：对应文件_thumbnails.scss

☑ 编译后版本：bootstrap.css文件第4402行～第4426行

使用方法：

通过“thumbnail”样式配合bootstrap的网格系统来实现。

前面也说过了，缩略图的实现是配合网格系统一起使用，假设我们一个产品列表，如下图所示：

先来看结构：

<code class="hljs applescript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"container"</span>>
    <<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"row"</span>>
        <<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"col-xs-6 col-md-3"</span>>
            <a href=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"#"</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"thumbnail"</span>>
                <img src=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"imgs/a.png"</span> style=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"width: 100%; display: block;"</span> alt=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>>
            </a>
        </<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>>
    …
    </<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>>
</<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

上面的结构表示的是在宽屏幕（可视区域大于768px）的时候，一行显示四个缩略图(单击全屏查看效果)：

在窄屏（可视区域小于768px）的时候，一行只显示两个缩略图：

• col-xs-超小屏幕 手机 (<768px),
• col-sm-小屏幕 平板 (≥768px),
• col-md-中等屏幕 桌面显示器 (≥992px)

class="col-xs-6 col-md-3"这个是响应式网格的语法， 你可以这样认为，当屏幕为小屏幕(<768px)时自动使用class="col-xs-6" 当屏幕为中屏(>=768px)时自动使用 class="col-md-3" BootStrap总共分为12列，上面的代码表示在极小屏幕时每6份(占一半)，即6，中大屏幕是占3份。

实现原理：

布局实现的主要是依靠于Bootstrap框架的网格系统，而缩略图对应的样式代码：

/bootstrap.css文件第4402行～第4426行/

<code class="hljs css has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.thumbnail</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">display</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> block</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">4</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-bottom</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">20</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">line-height</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">1.42857143</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#fff</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">1</span>px solid <span class="hljs-hexcolor" style="box-sizing: border-box;">#ddd</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-radius</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">4</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">-webkit-transition</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> all .<span class="hljs-number" style="box-sizing: border-box;">2</span>s ease-in-out</span></span>;
          <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">transition</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> all .<span class="hljs-number" style="box-sizing: border-box;">2</span>s ease-in-out</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.thumbnail</span> > <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">img</span>,
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.thumbnail</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">a</span> > <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">img</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-right</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> auto</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-left</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> auto</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">a</span><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.thumbnail</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:hover</span>,
<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">a</span><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.thumbnail</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:focus</span>,
<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">a</span><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.thumbnail</span><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.active</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#428bca</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.thumbnail</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.caption</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">9</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#333</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li></ul>

2、复杂缩略图

上一小节，展示的仅只有缩略图的一种使用方式，除了这种方式之外，还可以让缩略图配合标题、描述内容，按钮等：

在仅有缩略图的基础上，添加了一个div名为“caption“的容器，在这个容器中放置其他内容，比如说标题，文本描述，按钮等：

<code class="hljs xml has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"container"</span>></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"row"</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"col-xs-6 col-md-3"</span>></span>
            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">href</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"#"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"thumbnail"</span>></span>
                <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">img</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">src</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"imgs/1.jpg"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">style</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"height: 180px; width: 100%; display: block;"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">alt</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">""</span>></span>
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                <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">h3</span>></span>Bootstrap框架系列教程<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">h3</span>></span>
                <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">p</span>></span>Bootstrap框架是一个优秀的前端框，就算您是一位后端程序员或者你是一位不懂设计的前端人员，你也能依赖于Bootstrap制作做优美的网站...<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">p</span>></span>
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                    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">href</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"##"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"btn btn-primary"</span>></span>开始学习<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span>></span>
                    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">href</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"##"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"btn btn-info"</span>></span>正在学习<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span>></span>
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            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span>></span>
    …
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li></ul>

效果如下： 

3、警示框

在网站中，网页总是需要和用户一起做沟通与交流。特别是当用户操作上下文为用户提供一些有效的警示框，比如说告诉用户操作成功、操作错误、提示或者警告等。如下图所示：

在Bootstrap框架有一个独立的组件，实现上述的效果，这个组件被称为警示框。

源码版本：

☑ LESS版本：对应的源码文件alerts.less

☑ Sass版本：对应的源码文件_alerts.scss

☑ 编译后的版本：bootstrap.css文件第4427行～第4499行

4、默认警示框

Bootstrap框架通过“alert“样式来实现警示框效果。在默认情况之下，提供了四种不同的警示框效果：

1、成功警示框：告诉用用户操作成功，在“alert”样式基础上追加“alert-success”样式，具体呈现的是背景、边框和文本都是绿色；

2、信息警示框：给用户提供提示信息，在“alert”样式基础上追加“alert-info”样式，具体呈现的是背景、边框和文本都是浅蓝色；

3、警告警示框：提示用户小心操作（提供警告信息），在“alert”样式基础上追加“alert-warning”样式，具体呈现的是背景、边框、文本都是浅黄色；

4、错误警示框：提示用户操作错误，在“alert”样式基础上追加“alert-danger”样式，具体呈现的是背景、边框和文本都是浅红色。

使用方法：

具体使用的时候，可以在类名为“alert”的div容器里放置提示信息。实现不同类型警示框，只需要在“alert”基础上追加对应的类名，如下：

<code class="hljs applescript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert alert-success"</span> role=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert"</span>>恭喜您操作成功！</<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>>
<<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert alert-info"</span> role=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert"</span>>请输入正确的密码</<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>>
<<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert alert-warning"</span> role=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert"</span>>您已操作失败两次，还有最后一次机会</<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>>
<<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert alert-danger"</span> role=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert"</span>>对不起，您输入的密码有误</<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

运行效果如下：

实现原理：

其中“alert”样式的源码主要是设置了警示框的背景色、边框、圆角和文字颜色。另外对其内部几个元素h4、p、ul和“.alert-link”做了样式上的特殊处理：

/bootstrap.css文件第4427行～第4446行/

<code class="hljs css has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">15</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-bottom</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">20</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">1</span>px solid transparent</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-radius</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">4</span>px</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">h4</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-top</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> inherit</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">font-weight</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> bold</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert</span> > <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">p</span>,
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert</span> > <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">ul</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-bottom</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert</span> > <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">p</span> + <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">p</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-top</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">5</span>px</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li></ul>

不同类型的警示框，主要是通过“alert-success”、“alert-info”、“alert-warning”和“alert-danger”样式来实现：

/bootstrap.css文件第4456行～第4499行/

<code class="hljs css has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-success</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#3c763d</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#dff0d8</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#d6e9c6</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-success</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">hr</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-top-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#c9e2b3</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-success</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#2b542c</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-info</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#31708f</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#d9edf7</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#bce8f1</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-info</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">hr</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-top-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#a6e1ec</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-info</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#245269</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-warning</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#8a6d3b</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#fcf8e3</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#faebcc</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-warning</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">hr</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-top-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#f7e1b5</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-warning</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#66512c</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-danger</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#a94442</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#f2dede</span></span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#ebccd1</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-danger</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">hr</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border-top-color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#e4b9c0</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-danger</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#843534</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li></ul>

5、可关闭的警示框

大家在平时浏览网页的时候，会发现一些警示框带有关闭按钮，用户一点击关闭按钮就能自动关闭显示的警示框（也就是让警示框隐藏不显示）。在Bootstrap框架中的警示框也具有这样的功能。

使用方法：

只需要在默认的警示框里面添加一个关闭按钮。然后进行三个步骤：

• 1、需要在基本警示框“alert”的基础上添加“alert-dismissable”样式。

• 2、在button标签中加入class="close"类，实现警示框关闭按钮的样式。

• 3、要确保关闭按钮元素上设置了自定义属性：“data-dismiss="alert"”（因为可关闭警示框需要借助于Javascript来检测该属性，从而控制警示框的关闭）。

具体使用如下：

<code class="hljs applescript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span> <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert alert-success alert-dismissable"</span> role=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert"</span>>
    <button <span class="hljs-type" style="box-sizing: border-box;">class</span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"close"</span> type=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"button"</span> data-dismiss=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alert"</span>>&<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">times</span>;</button>
    恭喜您操作成功！
</<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">div</span>></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

运行效果如下：

原理分析：

在样式上，需要在基本警示框“alert”的基础上添加“alert-dismissable”样式，这样就可以实现带关闭功能的警示框。

/bootstrap.css文件第4447行～第4455行/

<code class="hljs css has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-dismissable</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding-right</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">35</span>px</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-dismissable</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.close</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">position</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> relative</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">top</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> -<span class="hljs-number" style="box-sizing: border-box;">2</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">right</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> -<span class="hljs-number" style="box-sizing: border-box;">21</span>px</span></span>;
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> inherit</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

6、警示框的链接

有时候你可能想在警示框中加入链接地址，用来告诉用户跳到某一个地方或新的页面。而这个时候你又想让用户能明显的看出来这是链接地址。在Bootstrap框架中对警示框里的链接样式做了一个高亮显示处理。为不同类型的警示框内的链接进行了加粗处理，并且颜色相应加深。

实现方法：

Bootstrap框架是通过给警示框加的链接添加一个名为“alert-link”的类名，通过“alert-link”样式给链接提供高亮显示。

具体使用如下：

<code class="hljs xml has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"alert alert-warning"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">role</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"alert"</span>></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">strong</span>></span>Warning!<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">strong</span>></span>
     忘记密码？---><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">href</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"##"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"alert-link"</span>></span>请点击此处<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"alert alert-danger"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">role</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"alert"</span>></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">strong</span>></span>Oh snap!<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">strong</span>></span>
    密码输入错误---><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">href</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"##"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">class</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"alert-link"</span>></span>请点击此处找回密码。。<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">a</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">div</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

运行效果如下：

实现原理：

实现样式如下：

/bootstrap.css文件第4437行～第4439行/

<code class="hljs css has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">font-weight</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> bold</span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

/不同类型警示框中链接的文本颜色/

<code class="hljs css has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-success</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#2b542c</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-info</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#245269</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-warning</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#66512c</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span>
<span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-danger</span> <span class="hljs-class" style="box-sizing: border-box; color: rgb(155, 112, 63);">.alert-link</span> <span class="hljs-rules" style="box-sizing: border-box;">{
  <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">color</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#843534</span></span></span>;
<span class="hljs-rule" style="box-sizing: border-box;">}</span></span></code>