我琢磨了一天。。。bootstarp三个版本全试过了，还有jquery。。。也不行。到最后我下载了案列模板把里面十多个js添加进去，，，才成功了，，，现在的问题是，，，g开头那些图标好像引用不了

谢谢啊，我少加了个bootstrap.min.js

<div class="navbar navbar-default">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target=".navbar-collapse">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="#">Project name</a>
        </div>
        <div class="navbar-collapse collapse">
            <ul class="nav navbar-nav">
                <li class="active"><a href="#">Home</a></li>
                <li><a href="#about">About</a></li>
                <li><a href="#contact">Contact</a></li>
                <li class="dropdown">
                    <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <span class="caret"></span></a>
                    <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 class="dropdown-header">Nav header</li>
                        <li><a href="#">Separated link</a></li>
                        <li><a href="#">One more separated link</a></li>
                    </ul>
                </li>
            </ul>
        </div><!--/.nav-collapse -->
    </div>
</div>

发代码