Bootstrap树形菜单，就这么简单

一、CSS部分：

.tree {
    min-height:20px;
    padding:19px;
    margin-bottom:20px;
    background-color:#fbfbfb;
    border:1px solid #999;
    -webkit-border-radius:4px;
    -moz-border-radius:4px;
    border-radius:4px;
    -webkit-box-shadow:inset 0 1px 1px rgba(0, 0, 0, 0.05);
    -moz-box-shadow:inset 0 1px 1px rgba(0, 0, 0, 0.05);
    box-shadow:inset 0 1px 1px rgba(0, 0, 0, 0.05)
}
.tree li {
    list-style-type:none;
    margin:0;
    padding:10px 5px 0 5px;
    position:relative
}
.tree li::before, .tree li::after {
    content:\'\';
    left:-20px;
    position:absolute;
    right:auto
}
.tree li::before {
    border-left:1px solid #999;
    bottom:50px;
    height:100%;
    top:0;
    width:1px
}
.tree li::after {
    border-top:1px solid #999;
    height:20px;
    top:25px;
    width:25px
}

.tree li span {
    -moz-border-radius:5px;
    -webkit-border-radius:5px;
    border:1px solid #999;
    border-radius:5px;
    display:inline-block;
    padding:3px 8px;
    text-decoration:none
}
.tree li.parent_li>span {
    cursor:pointer
}
.tree>ul>li::before, .tree>ul>li::after {
    border:0
}
.tree li:last-child::before {
    height:30px
}
.tree li.parent_li>span:hover, .tree li.parent_li>span:hover+ul li span {
    background:#eee;
    border:1px solid #94a0b4;
    color:#000
}

.icon-plus-sign{display:inline-block;width:16px;height:16px;background:url(\'../Images/bg/ico_small.png\') left -44px no-repeat;}
.icon-minus-sign{display:inline-block;width:16px;height:16px;background:url(\'../Images/bg/ico_small.png\') left 0px no-repeat;}

完全可以自己建一个Css文件，将他们考入，引用。

.tree li::before, .tree li::after {}
.tree li::before {}
.tree li::after {}

主要用上面三个属性实现树的前面树形线，注意是用css3的before 和after实现

二、HTML部分：

 <div class="tree well">
            <ul>
                <li>
                    <span><i class="icon-plus-sign"></i> Parent</span><a href="">Goes somewhere</a>
                    <ul>
                        <li>
                            <span><i class="icon-plus-sign"></i> Child</span> <a href="">Goes somewhere</a>
                            <ul>
                                <li>
                                    <span><i class="icon-leaf"></i> Grand Child</span> <a href="">Goes somewhere</a>
                                </li>
                            </ul>
                        </li>
                        <li>
                            <span><i class="icon-plus-sign"></i> Child</span> <a href="">Goes somewhere</a>
                            <ul>
                                <li>
                                    <span><i class="icon-leaf"></i> Grand Child</span> <a href="">Goes somewhere</a>
                                </li>
                                <li>
                                    <span><i class="icon-plus-sign"></i> Grand Child</span> <a href="">Goes somewhere</a>
                                    <ul>
                                        <li>
                                            <span><i class="icon-plus-sign"></i> Great Grand Child</span> <a href="">Goes somewhere</a>
                                            <ul>
                                                <li>
                                                    <span><i class="icon-leaf"></i> Great great Grand Child</span> <a href="">Goes somewhere</a>
                                                </li>
                                                <li>
                                                    <span><i class="icon-leaf"></i> Great great Grand Child</span> <a href="">Goes somewhere</a>
                                                </li>
                                            </ul>
                                        </li>
                                        <li>
                                            <span><i class="icon-leaf"></i> Great Grand Child</span> <a href="">Goes somewhere</a>
                                        </li>
                                        <li>
                                            <span><i class="icon-leaf"></i> Great Grand Child</span> <a href="">Goes somewhere</a>
                                        </li>
                                    </ul>
                                </li>
                                <li>
                                    <span><i class="icon-leaf"></i> Grand Child</span> <a href="">Goes somewhere</a>
                                </li>
                            </ul>
                        </li>
                    </ul>
                </li>

                <li>
                    <span><i class="icon-plus-sign"></i> Parent2</span> <a href="">Goes somewhere</a>
                    <ul>
                        <li>
                            <span><i class="icon-leaf"></i> Child</span> <a href="">Goes somewhere</a>
                        </li>
                    </ul>
                </li>
            </ul>
        </div>

三、JQ:

   <script type="text/javascript">
        var d=true;
        $(function () {
            $(\'.tree li:has(ul)\').addClass(\'parent_li\').find(\' > span\').attr(\'title\', \'Collapse this branch\');
            $(\'.tree li.parent_li > span\').on(\'click\', function (e) {
                var d = $(this).siblings(\'ul\').is(":visible");
                $(this).siblings(\'ul\').slideToggle(\'fast\');//.siblings(\'dt\').css(\'background-position\',\'right -40px\');
                if (d) {
                    console.log($(this).find(">i"));
                    $(this).find(">i").addClass(\'icon-minus-sign\').removeClass(\'icon-plus-sign\');
                    
                } else {
                  //  $(this).find(\' > i\').addClass(\'icon-minus-sign\').removeClass(\'icon-plus-sign\');
                    $(this).find(">i").addClass(\'icon-plus-sign\').removeClass(\'icon-minus-sign\');
                }
                e.stopPropagation();
            });
        });

    </script>

4、树形折叠图片：

为这两个样式准备

.icon-plus-sign{display:inline-block;width:16px;height:16px;background:url(\'../Images/bg/ico_small.png\') left -44px no-repeat;}
.icon-minus-sign{display:inline-block;width:16px;height:16px;background:url(\'../Images/bg/ico_small.png\') left 0px no-repeat;}