1. AngularJS服务
AngularJS可注入类型包括：Service、Factory、Provider、Value及Constant。
2. Service
AngularJS Service是封装了一些特定业务逻辑的单例对象，在每个应用中只会被实例化一次（由$injector实例化），且延迟加载（需要时才会创建）。
AngularJS Service对外提供方法供其他组件调用。
2.1 AngularJS内置Service对象
AngularJS内置30多个服务。
1>. $location：返回当前页面的 URL 地址
<!DOCTYPE html>
<html ng-app="app">
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="../lib/angular.min.js"></script>
<script type="text/javascript">
var app = angular.module("app", []);
app.controller("HelloCtrl", ["$scope", "$location", function ($scope, $location) {
$scope.url = $location.absUrl();
}]);
</script>
</head>
<body>
<div ng-controller="HelloCtrl">
{{ url }}
</div>
</body>
</html>
2>.$timeout：在指定的毫秒数后调用函数或计算表达式，只执行一次。
<!DOCTYPE html>
<html ng-app="app">
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="../lib/angular.min.js"></script>
<script type="text/javascript">
var app = angular.module("app", []);
app.controller("HelloCtrl", ["$scope", "$timeout", function ($scope, $timeout) {
$scope.text = "Hello World!";
$timeout(function () {
$scope.text = "Hello AngularJS!";
}, 2000);
}]);
</script>
</head>
<body>
<div ng-controller="HelloCtrl">
{{ text }}
</div>
</body>
</html>
3>.$interval：按照指定的周期（以毫秒计）来调用函数或计算表达式，会多次不停地调用执行。
<!DOCTYPE html>
<html ng-app="app">
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="../lib/angular.min.js"></script>
<script type="text/javascript">
var app = angular.module("app", []);
app.controller("HelloCtrl", ["$scope", "$interval", function ($scope, $interval ) {
$scope.time = new Date().toLocaleTimeString();
$interval (function () {
$scope.time = new Date().toLocaleTimeString();
}, 1000);
}]);
</script>
</head>
<body>
<div ng-controller="HelloCtrl">
{{ time }}
</div>
</body>
</html>
不使用 $interval 服务的情况下，运用 $apply显示时间。
<!DOCTYPE html>
<html ng-app="app">
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="../lib/angular.min.js"></script>
<script type="text/javascript">
var app = angular.module("app", []);
app.controller("HelloCtrl", ["$scope", function ($scope) {
$scope.time = new Date().toLocaleTimeString();
$scope.setTime = function() {
// $apply访问并修改数据
$scope.$apply (function () {
$scope.time = new Date().toLocaleTimeString();
});
} setInterval($scope.setTime, 1000);
}]);
</script>
</head>
<body>
<div ng-controller="HelloCtrl">
{{ time }}
</div>
</body>
</html>
2.2 自定义服务
AngularJS自定义服务语法格式：
var app = angular.module("app", []);
app.service("serviceName", function(){
// 属性、方法
});
其中：
第一个参数：Service名称
第二个参数：Service对象的构造函数，可以定义属性和方法来封装处理一些逻辑。
示例：
<!DOCTYPE html>
<html ng-app="app">
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="../lib/angular.min.js"></script>
<script type="text/javascript">
var app = angular.module("app", []);
app.controller("HelloCtrl", ["$scope", "$datetime", function ($scope, $datetime) {
$scope.time = $datetime.getTime();
}]);
app.service("$datetime", function(){
this.getTime = function() {
return new Date().toLocaleTimeString();
};
});
</script>
</head>
<body>
<div ng-controller="HelloCtrl">
{{ time }}
</div>
</body>
</html>
示例：
<!DOCTYPE html>
<html ng-app="app">
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="../lib/angular.min.js"></script>
<script type="text/javascript">
var app = angular.module("app", []);
app.controller("HelloCtrl", ["$scope", "$interval", "$datetime", function ($scope, $interval, $datetime) {
$interval (function () {
$scope.time = $datetime.getTime();
}, 1000);
}]);
app.service("$datetime", function(){
this.getTime = function() {
return new Date().toLocaleTimeString();
};
});
</script>
</head>
<body>
<div ng-controller="HelloCtrl">
{{ time }}
</div>
</body>
</html>
示例：在自定义的Service中可以注入其他Service对象。
<!DOCTYPE html>
<html ng-app="app">
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="../lib/angular.min.js"></script>
<script type="text/javascript">
var app = angular.module("app", []);
app.run(["$datetime", function ($datetime) {
$datetime.getTime();
}]);
app.service("$datetime", ["$interval", "$log", function($interval, $log) {
this.getTime = function() {
$interval (function () {
$log.info(new Date().toLocaleTimeString());
}, 1000);
};
}]);
</script>
</head>
<body>
</body>
</html>
3. Factory
4. Provider
5. Constant
constant创建的服务用来返回一个常量。
constant语法格式：
var app = angular.module("app", []);
app.constant(name, value);
其中，
参数name：创建服务的名称
value：一个常量，与服务名称对应的常量值或对象。当注入该服务之后，可以直接调用服务名对应的常量。