angularjs 缓存

设置缓存请求的数据：只有请求URL不变，就不会重新发请求

设置带定时时间的缓存：

.factory('cacheInterceptor', ['$cacheFactory', '$timeout', function($cacheFactory, $timeout) {
  var ttlMap = {};
  return {
    request: function(config) {
      if (config.ttl) {
        var ttl = config.ttl;
        delete config.ttl;
        config.cache = true;

        // If not in ttlMap then we set up a timer to delete, otherwise there's already a timer.
        if (!ttlMap[config.url]) {
          ttlMap[config.url] = true;
          $timeout(ttl)
          .then(function() {
            $cacheFactory.get('$http').remove(config.url);          
            delete ttlMap[config.url];
          });
        }
      }
      return config;
    }
  };
}])

.config(['$routeProvider', '$httpProvider', function($routeProvider, $httpProvider) {

  $httpProvider.interceptors.push('cacheInterceptor');

$http.get('/permissions.json', {timeToLive: Constant.timeToLive}).then(function(result){

.constant('Constant', {
  url: {
    logout: '/auth/logout'
  },
  timeToLive: 60*60*1000
})