AngularJS服务

栏目: JavaScript · 发布时间: 5年前

内容简介：AngularJS services are substitutable objects that are wired together using dependency injection (DI). You can use services to organize and share code across your app.AngularJS服务是使用依赖注入（DI）连接在一起的可替换对象。您可以使用服务在整个应用中组织和共享代码。AngularJS 提供了好多有用的服务，像$http,但是对于大多数

AngularJS services are substitutable objects that are wired together using dependency injection (DI). You can use services to organize and share code across your app.

AngularJS服务是使用依赖注入（DI）连接在一起的可替换对象。您可以使用服务在整个应用中组织和共享代码。

在 AngularJS 中，服务是一个函数或对象，可在你的 AngularJS 应用中使用。
服务提供了一种能在应用的整个生命周期内保持数据的方法，它能够在控制器之间进行通信，并保持数据的一致性。

AngularJS服务包括：

懒实例：当一个组件依赖它的时候，AngularJS只是实例化了一个服务
单例：依赖于服务的每个组件都会获得对服务工厂生成的单个实例的引用。
- 服务是一个单例对象，在每个应用中只会被实例化一次（被$injector）

AngularJS 提供了好多有用的服务，像$http,但是对于大多数的应用程度，你需要创建你自已的服务。

Note: Like other core AngularJS identifiers, built-in services always start with $ (e.g. $http). 
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像其他核心AngularJS标识符一样，创建服务通常需要用到 http）

使用服务：

To use an AngularJS service, you add it as a dependency for the component (controller, service, filter or directive) that depends on the service. AngularJS's dependency injection subsystem takes care of the rest.

为了使用AngularJS服务，请将其添加为依赖于服务的组件（控制器，服务，过滤器或指令）的依赖项。AngularJS的依赖注入子系统负责其余部分。

使用内建服务

AngularJS 内建了30 多个服务。有个 $location 服务，它可以返回当前页面的 URL 地址。

<!DOCTYPE html>
<html ng-app="app">
<head lang="zh_CN">
    <meta charset="utf-8">
    <title>Angular服务学习</title>
    <script src="http://apps.bdimg.com/libs/angular.js/1.4.6/angular.min.js" type="text/javascript"></script>
</head>
<body>
<div ng-controller="ctrl">
    <p>当前页面的Url:</p>
    <h3>{{myUrl}}</h3>
</div>
</body>
<script>
    let app = angular.module('app', []);
    app.controller('ctrl', function ($scope, $location) {
        $scope.myUrl = $location.absUrl();
    })
</script>
</html>
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注意 $location 服务是作为一个参数传递到 controller 中。如果要使用它，需要在 controller 中定义。

使用自定义服务

<!DOCTYPE html>
<html ng-app="app">
<head lang="zh_CN">
    <meta charset="utf-8">
    <title>Angular服务学习</title>
    <script src="http://apps.bdimg.com/libs/angular.js/1.4.6/angular.min.js" type="text/javascript"></script>
</head>
<body>
<div id="simple" ng-controller="MyController">
    <p>Let's try this simple notify service, injected into the controller...</p>
    <input ng-init="message='test'" ng-model="message" >
    <button ng-click="callNotify(message);">NOTIFY</button>
    <p>(you have to click 3 times to see an alert)</p>
</div>
</body>
<script>
    let app = angular.module('app', []);
    app.controller('MyController', ['$scope', 'notify', function($scope, notify) {
        $scope.callNotify = function(msg) {
            notify(msg);
        };
    }]).
    factory('notify', ['$window', function(win) {
        var msgs = [];
        return function(msg) {
            msgs.push(msg);
            if (msgs.length === 3) {
                win.alert(msgs.join('\n'));
                msgs = [];
            }
        };
    }]);
</script>
</html>
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创建服务

创建服务的三种方式：

factory服务
$provide服务

Application developers are free to define their own services by registering the service's name and service factory function, with an AngularJS module.

应用程序开发人员可以通过使用AngularJS模块注册服务的名称和服务工厂函数来自由定义自己的服务。

The service factory function generates the single object or function that represents the service to the rest of the application. The object or function returned by the service is injected into any component (controller, service, filter or directive) that specifies a dependency on the service.

服务工厂函数生成单个对象或函数表示服务给应用程序的其余部分。服务返回的对象或函数将注入到指定服务依赖关系的任何组件（控制器，服务，过滤器或指令）中。

注册服务

Services are registered to modules via the Module API. Typically you use the Module factory API to register a service:

服务通过Module API注册到模块。通常，您使用Module factory API注册服务：

var myModule = angular.module('myModule', []);
myModule.factory('serviceId', function() {
  var shinyNewServiceInstance;
  // factory function body that constructs shinyNewServiceInstance
  return shinyNewServiceInstance;
});
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Note that you are not registering a service instance, but rather a factory function that will create this instance when called.

请注意，您没有注册服务实例，而是在调用时将创建此实例的工厂函数。

依赖（Dependencies）

Services can have their own dependencies. Just like declaring dependencies in a controller, you declare dependencies by specifying them in the service's factory function signature. 服务可以有它们自己的依赖项。就像在控制器中声明依赖项一样，你可以通过在服务工厂函数签名中指定依赖项来声明依赖项。 For more on dependencies, see the dependency injection docs. 有关依赖项的更多信息，请参阅依赖注入的文档 The example module below has two services, each with various dependencies: 下面的示例模块有两个服务，每个服务都有各种依赖项：

var batchModule = angular.module('batchModule', []);

/**
 * The `batchLog` service allows for messages to be queued in memory and flushed
 * to the console.log every 50 seconds.
 *
 * @param {*} message Message to be logged.
 */
batchModule.factory('batchLog', ['$interval', '$log', function($interval, $log) {
  var messageQueue = [];

  function log() {
    if (messageQueue.length) {
      $log.log('batchLog messages: ', messageQueue);
      messageQueue = [];
    }
  }

  // start periodic checking
  $interval(log, 50000);

  return function(message) {
    messageQueue.push(message);
  }
}]);

/**
 * `routeTemplateMonitor` monitors each `$route` change and logs the current
 * template via the `batchLog` service.
 */
batchModule.factory('routeTemplateMonitor', ['$route', 'batchLog', '$rootScope',
  function($route, batchLog, $rootScope) {
    return {
      startMonitoring: function() {
        $rootScope.$on('$routeChangeSuccess', function() {
          batchLog($route.current ? $route.current.template : null);
        });
      }
    };
  }]);
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In the example, note that: 在示例中，请注意：

The batchLog service depends on the built-in log services.
- 该batchLog服务取决于内置 log服务
The routeTemplateMonitor service depends on the built-in $route service and our custom batchLog service.
- 该routeTemplateMonitor服务取决于内置$route 服务和我们的自定义batchLog服务。
Both services use the array notation to declare their dependencies.
- 两种服务都使用数组表示法来声明它们的依赖项。
The order of identifiers in the array is the same as the order of argument names in the factory function.
- 数组中标识符的顺序与工厂函数中参数名称的顺序相同。

使用 provide）

You can also register services via the provide注册服务

angular.module('myModule', []).config(['$provide', function($provide) {
  $provide.factory('serviceId', function() {
    var shinyNewServiceInstance;
    // factory function body that constructs shinyNewServiceInstance
    return shinyNewServiceInstance;
  });
}]);
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This technique is often used in unit tests to mock out a service's dependencies. 这个技术通过用于单元测试，以模拟服务的依赖关系

单元测试（Unit Testing）

The following is a unit test for the notify service from the Creating AngularJS Services example above. The unit test example uses a Jasmine spy (mock) instead of a real browser alert.

var mock, notify;
beforeEach(module('myServiceModule'));
beforeEach(function() {
  mock = {alert: jasmine.createSpy()};

  module(function($provide) {
    $provide.value('$window', mock);
  });

  inject(function($injector) {
    notify = $injector.get('notify');
  });
});

it('should not alert first two notifications', function() {
  notify('one');
  notify('two');

  expect(mock.alert).not.toHaveBeenCalled();
});

it('should alert all after third notification', function() {
  notify('one');
  notify('two');
  notify('three');

  expect(mock.alert).toHaveBeenCalledWith("one\ntwo\nthree");
});

it('should clear messages after alert', function() {
  notify('one');
  notify('two');
  notify('third');
  notify('more');
  notify('two');
  notify('third');

  expect(mock.alert.calls.count()).toEqual(2);
  expect(mock.alert.calls.mostRecent().args).toEqual(["more\ntwo\nthird"]);
});
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