原文来自：http://blog.manishchhabra.com/2013/09/angularjs-service-vs-factory-with-example/
What is an AngularJS service or factory?
Singleton.
Yes! That one word is enough to define AngularJS services. The purpose of AngularJS service / factory function is to generate a single object or function that represents the service to rest of the application. That object or function is passed as a parameter to any other factory function which specifies a dependency on this service.
Services
Syntax: module.service(‘serviceName‘, function);
Result: When declaring serviceName as an injectable argument you will be provided with the instance of a function passed to module.service.
Usage: Could be useful for sharing utility functions that are useful to invoke by simply appending () to the injected function reference. Could also be run with injectedArg.call(this) or similar.
Example:
1 varapp = angular.module(‘myApp‘, []);
2
3 // Service definition
4 app.service(‘testService‘, function(){
5 this.sayHello= function(text){
6 return"Service says \"Hello "+ text + "\"";
7 };
8 });
9
10 // AngularJS Controller that uses the service
11 functionHelloCtrl($scope, testService)
12 {
13 $scope.fromService = testService.sayHello("World");
14 }
Factories
Syntax: module.factory(‘factoryName‘, function);
Result: When declaring factoryName as an injectable argument you will be provided the value that is returned by invoking the function reference passed to module.factory.
Usage: Could be useful for returning a ‘class’ function that can then be new’ed to create instances.
1 varapp = angular.module(‘myApp‘, []);
2
3 // Factory
4 app.factory(‘testFactory‘, function(){
5 return{
6 sayHello: function(text){
7 return"Factory says \"Hello "+ text + "\"";
8 }
9 }
10 });
11
12 // AngularJS Controller that uses the factory
13 functionHelloCtrl($scope, testFactory)
14 {
15 $scope.fromFactory = testFactory.sayHello("World");
16 }