归属module (name,constructor)
提供一个服务
与factory 相似

var app = angular.module('myapp',[]).value('testvalue','widuu').service('testservice',function(testvalue) {
    this.lable = function() {
        return "this will output:hello " + testvalue;
    }
});
app.controller('mytest',function($scope,testvalue,testservice) {
    $scope.test = "hello " + testvalue;
    $scope.output = testservice.lable();
});