源碼先放在這里薄啥，以后來補充撞反，大部分注釋寫了鸦列，很好明白租冠。

/*
 * angular-ui-bootstrap
 * http://angular-ui.github.io/bootstrap/

 * Version: 1.2.4 - 2016-03-06
 * License: MIT
 */angular.module("ui.bootstrap", ["ui.bootstrap.tpls","ui.bootstrap.collapse"]);
angular.module("ui.bootstrap.tpls", []);
angular.module('ui.bootstrap.collapse', [])

  .directive('uibCollapse', ['$animate', '$q', '$parse', '$injector', function($animate, $q, $parse, $injector) {
    var $animateCss = $injector.has('$animateCss') ? $injector.get('$animateCss') : null;
    return {
      link: function(scope, element, attrs) {
        var expandingExpr = $parse(attrs.expanding),//假如指令屬性中有expanding方法，則用$attr獲取
            expandedExpr = $parse(attrs.expanded),//假如屬性中有expanded方法薯嗤，則用$attr獲取
            collapsingExpr = $parse(attrs.collapsing),//假如屬性中有collapsingExpr方法顽爹，則用$attr獲取
            collapsedExpr = $parse(attrs.collapsed);//假如屬性中有collapsedExpr方法，則用$attr獲取
//$parse和$eval都是解析字符串骆姐，區(qū)別是$parse是作為單獨的一個服務存在镜粤，$eval是作為單獨的一個scope方法來使用的
        if (!scope.$eval(attrs.uibCollapse)) {//如果uib-collapse為false的話，就為元素添加如下樣式和屬性
          element.addClass('in')
            .addClass('collapse')
            .attr('aria-expanded', true)
            .attr('aria-hidden', false)
            .css({height: 'auto'});
        }
//展開方法玻褪，由shouldCollapse負責監(jiān)聽肉渴，并且通過$q來達到展開折疊前后事件發(fā)生的控制
        function expand() {
          if (element.hasClass('collapse') && element.hasClass('in')) { //如果已經是展開的就返回
            return;
          }
//查到的資料顯示 resolve是$q.deffer()的方法，不知這里為什么$q怎么回事带射。
          $q.resolve(expandingExpr(scope))//成功執(zhí)行的信息黄虱，傳遞下去
            .then(function() {
              element.removeClass('collapse')
                .addClass('collapsing')
                .attr('aria-expanded', true)
                .attr('aria-hidden', false);

              if ($animateCss) {
                $animateCss(element, {
                  addClass: 'in',
                  easing: 'ease',
                  to: { height: element[0].scrollHeight + 'px' }
                }).start()['finally'](expandDone);
              } else {
                $animate.addClass(element, 'in', {
                  to: { height: element[0].scrollHeight + 'px' }
                }).then(expandDone);
              }
            });
        }

        function expandDone() {
          element.removeClass('collapsing')
            .addClass('collapse')
            .css({height: 'auto'});
          expandedExpr(scope);
        }

        function collapse() {
          if (!element.hasClass('collapse') && !element.hasClass('in')) {
            return collapseDone();
          }

          $q.resolve(collapsingExpr(scope))
            .then(function() {
              element
                // IMPORTANT: The height must be set before adding "collapsing" class.
                // Otherwise, the browser attempts to animate from height 0 (in
                // collapsing class) to the given height here.
                .css({height: element[0].scrollHeight + 'px'})
                // initially all panel collapse have the collapse class, this removal
                // prevents the animation from jumping to collapsed state
                .removeClass('collapse')
                .addClass('collapsing')
                .attr('aria-expanded', false)
                .attr('aria-hidden', true);

              if ($animateCss) {
                $animateCss(element, {
                  removeClass: 'in',
                  to: {height: '0'}
                }).start()['finally'](collapseDone);
              } else {
                $animate.removeClass(element, 'in', {
                  to: {height: '0'}
                }).then(collapseDone);
              }
            });
        }

        function collapseDone() {
          element.css({height: '0'}); // Required so that collapse works when animation is disabled
          element.removeClass('collapsing')
            .addClass('collapse');
          collapsedExpr(scope);
        }
//監(jiān)聽展開折疊變化
        scope.$watch(attrs.uibCollapse, function(shouldCollapse) {
          if (shouldCollapse) {
            collapse();
          } else {
            expand();
          }
        });
      }
    };
  }]);