Bootstrap----按钮式下拉菜单Button-dropdowns

如图说明：

1、单按钮下拉菜单：只要改变一些基本的标记，就能把按钮变成下拉菜单的开关。

2、有间隔的按钮下拉菜单：分裂式按钮下拉菜单也需要同样的改变一些标记，但只是多一个分开的按钮。

3、有不同尺寸的按钮下来菜单：按钮式下拉菜单适用所有尺寸的按钮

4、Dropup 变种（向上弹出菜单）：给父元素添加 .dropup 类就能使触发的下拉菜单朝上方打开。

其中，HTML代码为：

<!--按钮式下拉菜单 Button-dropdowns start-->
<h3 id="Button-dropdowns">按钮式下拉菜单 Button-dropdowns</h3>
<hr>
<div class="container">
     <h5 >单按钮下拉菜单</h5>
     <div class="btn-group">
          <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown" aria-expanded="false">Action <span class="caret"></span></button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group">
          <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown" aria-expanded="false">Action <span class="caret"></span></button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group">
          <button type="button" class="btn btn-success dropdown-toggle" data-toggle="dropdown" aria-expanded="false">Action <span class="caret"></span></button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <h5>有间隔的按钮下拉菜单</h5>
     <div class="btn-group">
          <button type="button" class="btn btn-info">Info</button>
          <button type="button" class="btn btn-info dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
                  <span class="caret"></span>
                  <span class="sr-only">Toggle Dropdown</span>
          </button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group">
          <button type="button" class="btn btn-warning">Warning</button>
          <button type="button" class="btn btn-warning dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
                  <span class="caret"></span>
                  <span class="sr-only">Toggle Dropdown</span>
          </button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group">
          <button type="button" class="btn btn-danger">Danger</button>
          <button type="button" class="btn btn-danger dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
                  <span class="caret"></span>
                  <span class="sr-only">Toggle Dropdown</span>
          </button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group">
          <button type="button" class="btn btn-link">Danger</button>
          <button type="button" class="btn btn-link dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
                  <span class="caret"></span>
                  <span class="sr-only">Toggle Dropdown</span>
          </button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <h5>有不同尺寸的按钮下来菜单</h5>
     <div class="btn-group">
          <button class="btn btn-default btn-lg dropdown-toggle" type="button" data-toggle="dropdown" aria-expanded="false">Large button <span class="caret"></span></button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group">
          <button class="btn btn-default btn-sm dropdown-toggle" type="button" data-toggle="dropdown" aria-expanded="false">Large button <span class="caret"></span></button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group">
          <button class="btn btn-default btn-xs dropdown-toggle" type="button" data-toggle="dropdown" aria-expanded="false">Large button <span class="caret"></span></button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <h5>有Dropop变种-向上弹出下拉菜单</h5>
     <div class="btn-group dropup">
          <button type="button" class="btn btn-default">Dropup</button>
          <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
                  <span class="caret"></span>
                  <span class="sr-only">Toggle Dropdown</span>
          </button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
     <div class="btn-group dropup">
          <button type="button" class="btn btn-danger">Dropup</button>
          <button type="button" class="btn btn-danger dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
                  <span class="caret"></span>
                  <span class="sr-only">Toggle Dropdown</span>
          </button>
          <ul class="dropdown-menu" role="menu">
              <li><a href="#">ACTION</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li class="divider"></li>
              <li><a href="#">Separated link</a></li>
          </ul>
     </div>
</div>
<!--按钮式下拉菜单 Button-dropdowns end-->

 

CSS代码为：

/*下拉菜单-六种颜色btn-default\primary\success\info\warning\danger\link Button-dropdowns*/
.btn {display: inline-block;padding: 6px 12px;margin-bottom: 0;font-size: 14px;font-weight: normal;line-height: 1.42857143;text-align: center;white-space: nowrap;vertical-align: middle;-ms-touch-action: manipulation;touch-action: manipulation;cursor: pointer;-webkit-user-select: none;-moz-user-select: none;-ms-user-select: none;user-select: none;background-image: none;border: 1px solid transparent;border-radius: 4px;}
.btn:focus,.btn:active:focus,.btn.active:focus,.btn.focus,.btn:active.focus,.btn.active.focus {outline: thin dotted;outline: 5px auto -webkit-focus-ring-color;outline-offset: -2px;}
.btn:hover,.btn:focus,.btn.focus {color: #333;text-decoration: none;}
.btn:active,.btn.active {background-image: none;outline: 0;-webkit-box-shadow: inset 0 3px 5px rgba(0, 0, 0, .125);box-shadow: inset 0 3px 5px rgba(0, 0, 0, .125);}
.btn.disabled,.btn[disabled],fieldset[disabled] .btn {cursor: not-allowed;filter: alpha(opacity=65);-webkit-box-shadow: none;box-shadow: none;opacity: .65;}
a.btn.disabled,fieldset[disabled] a.btn {pointer-events: none;}
.btn-default {color: #333;background-color: #fff;border-color: #ccc;}
.btn-default:focus,.btn-default.focus {color: #333;background-color: #e6e6e6;border-color: #8c8c8c;}
.btn-default:hover {color: #333;background-color: #e6e6e6;border-color: #adadad;}
.btn-default:active,.btn-default.active,.open > .dropdown-toggle.btn-default {color: #333;background-color: #e6e6e6;border-color: #adadad;}
.btn-default:active:hover,.btn-default.active:hover,.open > .dropdown-toggle.btn-default:hover,.btn-default:active:focus,.btn-default.active:focus,.open > .dropdown-toggle.btn-default:focus,.btn-default:active.focus,.btn-default.active.focus,.open > .dropdown-toggle.btn-default.focus {color: #333;background-color: #d4d4d4;border-color: #8c8c8c;}
.btn-default:active,.btn-default.active,.open > .dropdown-toggle.btn-default {background-image: none;}
.btn-default.disabled,.btn-default[disabled],fieldset[disabled] .btn-default,.btn-default.disabled:hover,.btn-default[disabled]:hover,fieldset[disabled] .btn-default:hover,.btn-default.disabled:focus,.btn-default[disabled]:focus,fieldset[disabled] .btn-default:focus,.btn-default.disabled.focus,.btn-default[disabled].focus,fieldset[disabled] .btn-default.focus,.btn-default.disabled:active,.btn-default[disabled]:active,fieldset[disabled] .btn-default:active,.btn-default.disabled.active,.btn-default[disabled].active,fieldset[disabled] .btn-default.active {background-color: #fff;border-color: #ccc;}
.btn-default .badge {color: #fff;background-color: #333;}
.btn-primary {color: #fff;background-color: #337ab7;border-color: #2e6da4;}
.btn-primary:focus,.btn-primary.focus {color: #fff;background-color: #286090;border-color: #122b40;}
.btn-primary:hover {color: #fff;background-color: #286090;border-color: #204d74;}
.btn-primary:active,.btn-primary.active,.open > .dropdown-toggle.btn-primary {color: #fff;background-color: #286090;border-color: #204d74;}
.btn-primary:active:hover,.btn-primary.active:hover,.open > .dropdown-toggle.btn-primary:hover,.btn-primary:active:focus,.btn-primary.active:focus,.open > .dropdown-toggle.btn-primary:focus,.btn-primary:active.focus,.btn-primary.active.focus,.open > .dropdown-toggle.btn-primary.focus {color: #fff;background-color: #204d74;border-color: #122b40;}
.btn-primary:active,.btn-primary.active,.open > .dropdown-toggle.btn-primary {background-image: none;}.btn-primary.disabled,.btn-primary[disabled],fieldset[disabled] .btn-primary,.btn-primary.disabled:hover,.btn-primary[disabled]:hover,fieldset[disabled] .btn-primary:hover,.btn-primary.disabled:focus,.btn-primary[disabled]:focus,fieldset[disabled] .btn-primary:focus,.btn-primary.disabled.focus,.btn-primary[disabled].focus,fieldset[disabled] .btn-primary.focus,.btn-primary.disabled:active,.btn-primary[disabled]:active,fieldset[disabled] .btn-primary:active,.btn-primary.disabled.active,.btn-primary[disabled].active,fieldset[disabled] .btn-primary.active {background-color: #337ab7;border-color: #2e6da4;}
.btn-primary .badge {color: #337ab7;background-color: #fff;}
.btn-success {color: #fff;background-color: #5cb85c;border-color: #4cae4c;}
.btn-success:focus,.btn-success.focus {color: #fff;background-color: #449d44;border-color: #255625;}
.btn-success:hover {color: #fff;background-color: #449d44;border-color: #398439;}
.btn-success:active,.btn-success.active,.open > .dropdown-toggle.btn-success {color: #fff;background-color: #449d44;border-color: #398439;}
.btn-success:active:hover,.btn-success.active:hover,.open > .dropdown-toggle.btn-success:hover,.btn-success:active:focus,.btn-success.active:focus,.open > .dropdown-toggle.btn-success:focus,.btn-success:active.focus,.btn-success.active.focus,.open > .dropdown-toggle.btn-success.focus {color: #fff;background-color: #398439;border-color: #255625;}
.btn-success:active,.btn-success.active,.open > .dropdown-toggle.btn-success {background-image: none;}
.btn-success.disabled,.btn-success[disabled],fieldset[disabled] .btn-success,.btn-success.disabled:hover,.btn-success[disabled]:hover,fieldset[disabled] .btn-success:hover,.btn-success.disabled:focus,.btn-success[disabled]:focus,fieldset[disabled] .btn-success:focus,.btn-success.disabled.focus,.btn-success[disabled].focus,fieldset[disabled] .btn-success.focus,.btn-success.disabled:active,.btn-success[disabled]:active,fieldset[disabled] .btn-success:active,.btn-success.disabled.active,.btn-success[disabled].active,fieldset[disabled] .btn-success.active {background-color: #5cb85c;border-color: #4cae4c;}
.btn-success .badge {color: #5cb85c;background-color: #fff;}
.btn-info {color: #fff;background-color: #5bc0de;border-color: #46b8da;}
.btn-info:focus,.btn-info.focus {color: #fff;background-color: #31b0d5;border-color: #1b6d85;}
.btn-info:hover {color: #fff;background-color: #31b0d5;border-color: #269abc;}
.btn-info:active,.btn-info.active,.open > .dropdown-toggle.btn-info {color: #fff;background-color: #31b0d5;border-color: #269abc;}
.btn-info:active:hover,.btn-info.active:hover,.open > .dropdown-toggle.btn-info:hover,.btn-info:active:focus,.btn-info.active:focus,.open > .dropdown-toggle.btn-info:focus,.btn-info:active.focus,.btn-info.active.focus,.open > .dropdown-toggle.btn-info.focus {color: #fff;background-color: #269abc;border-color: #1b6d85;}
.btn-info:active,.btn-info.active,.open > .dropdown-toggle.btn-info {background-image: none;}
.btn-info.disabled,.btn-info[disabled],fieldset[disabled] .btn-info,.btn-info.disabled:hover,.btn-info[disabled]:hover,fieldset[disabled] .btn-info:hover,.btn-info.disabled:focus,.btn-info[disabled]:focus,fieldset[disabled] .btn-info:focus,.btn-info.disabled.focus,.btn-info[disabled].focus,fieldset[disabled] .btn-info.focus,.btn-info.disabled:active,.btn-info[disabled]:active,fieldset[disabled] .btn-info:active,.btn-info.disabled.active,.btn-info[disabled].active,fieldset[disabled] .btn-info.active {background-color: #5bc0de;border-color: #46b8da;}
.btn-info .badge {color: #5bc0de;background-color: #fff;}
.btn-warning {color: #fff;background-color: #f0ad4e;border-color: #eea236;}
.btn-warning:focus,.btn-warning.focus {color: #fff;background-color: #ec971f;border-color: #985f0d;}
.btn-warning:hover {color: #fff;background-color: #ec971f;border-color: #d58512;}
.btn-warning:active,.btn-warning.active,.open > .dropdown-toggle.btn-warning {color: #fff;background-color: #ec971f;border-color: #d58512;}
.btn-warning:active:hover,.btn-warning.active:hover,.open > .dropdown-toggle.btn-warning:hover,.btn-warning:active:focus,.btn-warning.active:focus,.open > .dropdown-toggle.btn-warning:focus,.btn-warning:active.focus,.btn-warning.active.focus,.open > .dropdown-toggle.btn-warning.focus {color: #fff;background-color: #d58512;border-color: #985f0d;}
.btn-warning:active,.btn-warning.active,.open > .dropdown-toggle.btn-warning {background-image: none;}
.btn-warning.disabled,.btn-warning[disabled],fieldset[disabled] .btn-warning,.btn-warning.disabled:hover,
.btn-warning[disabled]:hover,fieldset[disabled] .btn-warning:hover,.btn-warning.disabled:focus,.btn-warning[disabled]:focus,fieldset[disabled] .btn-warning:focus,.btn-warning.disabled.focus,.btn-warning[disabled].focus,fieldset[disabled] .btn-warning.focus,.btn-warning.disabled:active,.btn-warning[disabled]:active,fieldset[disabled] .btn-warning:active,.btn-warning.disabled.active,.btn-warning[disabled].active,fieldset[disabled] .btn-warning.active { background-color: #f0ad4e;border-color: #eea236;}
.btn-warning .badge {color: #f0ad4e;background-color: #fff;}
.btn-danger {color: #fff;background-color: #d9534f;border-color: #d43f3a;}
.btn-danger:focus,.btn-danger.focus {color: #fff;background-color: #c9302c;border-color: #761c19;}
.btn-danger:hover {color: #fff;background-color: #c9302c;border-color: #ac2925;}
.btn-danger:active,.btn-danger.active,.open > .dropdown-toggle.btn-danger {color: #fff;background-color: #c9302c;border-color: #ac2925;}
.btn-danger:active:hover,.btn-danger.active:hover,.open > .dropdown-toggle.btn-danger:hover,.btn-danger:active:focus,.btn-danger.active:focus,.open > .dropdown-toggle.btn-danger:focus,.btn-danger:active.focus,.btn-danger.active.focus,.open > .dropdown-toggle.btn-danger.focus {color: #fff;background-color: #ac2925;border-color: #761c19;}
.btn-danger:active,.btn-danger.active,.open > .dropdown-toggle.btn-danger {background-image: none;}
.btn-danger.disabled,.btn-danger[disabled],fieldset[disabled] .btn-danger,.btn-danger.disabled:hover,.btn-danger[disabled]:hover,fieldset[disabled] .btn-danger:hover,.btn-danger.disabled:focus,.btn-danger[disabled]:focus,fieldset[disabled] .btn-danger:focus,.btn-danger.disabled.focus,.btn-danger[disabled].focus,fieldset[disabled] .btn-danger.focus,.btn-danger.disabled:active,.btn-danger[disabled]:active,fieldset[disabled] .btn-danger:active,.btn-danger.disabled.active,.btn-danger[disabled].active,fieldset[disabled] .btn-danger.active {background-color: #d9534f;border-color: #d43f3a;}
.btn-danger .badge {color: #d9534f;background-color: #fff;}
.btn-link {font-weight: normal;color: #337ab7;border-radius: 0;}
.btn-link,.btn-link:active,.btn-link.active,.btn-link[disabled],fieldset[disabled] .btn-link {background-color: transparent;-webkit-box-shadow: none;box-shadow: none;}
.btn-link,.btn-link:hover,.btn-link:focus,.btn-link:active {border-color: transparent;}
.btn-link:hover,.btn-link:focus {color: #23527c;text-decoration: underline;background-color: transparent;}
.btn-link[disabled]:hover,fieldset[disabled] .btn-link:hover,.btn-link[disabled]:focus,fieldset[disabled] .btn-link:focus {color: #777;text-decoration: none;}
.btn-lg,.btn-group-lg > .btn {padding: 10px 16px;font-size: 18px;line-height: 1.3333333;border-radius: 6px;}
.btn-sm,.btn-group-sm > .btn {padding: 5px 10px;font-size: 12px;line-height: 1.5;border-radius: 3px;}
.btn-xs,.btn-group-xs > .btn {padding: 1px 5px;font-size: 12px;line-height: 1.5;border-radius: 3px;}

本地效果为：desk/bootstrap/boot_index.html#Button-dropdowns

官网效果查看：http://bootstrap.css88.com/components/#btn-dropdowns