AngularJS 简介
AngularJS 是一个 JavaScript 框架。它可通过 <script> 标签添加到 HTML 页面。
AngularJS 通过 指令 扩展了 HTML,且通过 表达式 绑定数据到 HTML。
什么是 AngularJS?
AngularJS 使得开发现代的单一页面应用程序(SPAs:Single Page Applications)变得更加容易。
AngularJS 把应用程序数据绑定到 HTML 元素。
AngularJS 可以克隆和重复 HTML 元素。
AngularJS 可以隐藏和显示 HTML 元素。
AngularJS 可以在 HTML 元素"背后"添加代码。
AngularJS 支持输入验证。
通常,在AngularJS中使用JSON作为存储数据的模型。我们可能这样在controller中写model:
app.controller('BookController',['$scope',function($scope){ $scope.book = { id:1, name:'', author:'', stores:[ {id:1, name:'', quantity:2}, {id:2, name:'', quantity:2}, ... ] }; }])
在视图中也许这样用到这个model:
<div ng-controller="BookController"> <span ng-bind="book.id"></span> <input type="text" ng-model="book.name"/> <input type="text" ng-model="book.author"/> </div>
当我们需要从服务端获取数据的时候,可能这样写:
app.controller('BookController',['$scope', '$http', function($scope, $http){ var bookId = 1; $http.get('api/books'+bookId).success(function(bookData){ $scope.book = bookData; }) $scope.deleteBook = function(){ $http.delete('api/books/' + bookId); } $scope.updateBook = function(){ $http.put('api/books/'+bookId, $scope.book); } $scope.getBookImageUrl = function(width, height){ return 'our/iamge/service' +bookId + '/width/height'; } $scope.isAvailable = function(){ if(!$scope.book.stores || $scope.book.stores.length === 0){ return false; } reutrn $scope.book.stores.some(function(store){ return store.quantity > 0; }) } }])
在视图中可能这样使用:
<div ng-controller="BookController"> <div ng-style="{backgroundImage: 'url('+getBookImageUrl(100,100)+')'}"></div> <span ng-bind="book.id"></span"text" ng-model="book.name"/> <input type="text" ng-model="book.author"/> is available: <span ng-bind="isAvailable() "></span> <button ng-click="deleteBook()">Delete</button> <button ng-click="updateBook">Update</button> </div>
以上,JSON格式的model只能在BookController中使用,如何在其他controller中也可以使用呢?
--通过factory方式
app.factory('Book', ['$http', function($http){ function Book(bookData){ if(bookData){ this.setData(bookData); } } Book.prototype = { setData: function(bookData){ angular.extend(this, bookData); }, load: function(id){ var scope = this; $http.get('api/books/' + bookId).success(function(bookData){ scope.setData(bookData); }) }, delete: function(bookId){ $http.delete('api/books/' + bookId); }, update: function(bookId){ $http.put('api/books/' + bookId, this); }, getImageUrl: function(width, height){ return 'our/image/service/' + this.book.id + '/' + width + '/' + height; }, isAvailable: funciton(){ if(!this.book.stores || this.book.stores.length === 0) { return false; } return this.book.stores.some(function(store){ return store.quantity > 0; }) } } return Book; }])
以上,通过factory的方式创建了类似Book的一个Data Model,现在可以注入到controller中去了。
app.controller('BookController', ['$scope', 'Book', function($scope, Book){ $scope.book = new Book(); $scope.book.load(1); }])
在视图中也会有相应的变化。
<div ng-controller="BookController"> <div ng-style="{backgroundImage: 'url(' + book.getImageUrl(100, 100) + ')'}"></div> <span ng-bind="book.id"></span> <input type="text" ng-model="book.name"/> <input type="text" ng-model="book.author"/> is abailble: <span ng-bind="book.isAvailabe() "></span> <button ng-click="book.delete()">Delete</button> <button ng-click="book.update()">Update</button> </div>
以上,多个controller可以使用同一个有关book的Data Model了,如果多个controller处理同一个有关book的Data Model呢?
app.factory('booksManager', ['$http', '$q', 'Book', function($http. $q, Book){ var booksManager = { _pool: {}, _retrieveInstance: function(bookId, bookData){ var instance = this._pool[bookId]; if(instance){ instance.setData(bookData); } else { instance = new Book(bookData); this._pool[bookId] = instance; } return instance; }, _seach: function(bookId){ reutrn this_.pool[bookId]; }, _load: function(bookId, deferred){ var scope = this; $http.get('api/books/' + bookId) .success(funciton(bookData){ var book = scope._retrieveInstance(bookData.id, bookData); deferred.resolve(book); }) .error(function(){ deferred.reject(); }) }, getBook: function(bookId){ var deferred = $q.defer(); var book = this._search(bookId); if(book){ deferred.resove(book); } else { this._load(bookId, deferred); } return deferred.promise; }, loadAllBooks: function(){ var deferred = $q.defer(); var scope = this; $http.get('api/books') .success(function(booksArray){ var books = []; booksArray.forEach(function(bookData){ var book = scope.l_retrieveInstance(bookData.id, bookData); books.push(book); }); deferred.resolve(books); }) .error(function(){ deferred.reject(); }); return deferred.promise; }, setBook: function(bookData){ var scope = this; var book = this._search(bookData.id); if(book){ book.setData(bookData); } else { book = scope._retrieveInstance(bookData); } return book; } }; return booksManager; }])
Book服务去掉load方法。
app.factory('Book', ['$http', function($http) { function Book(bookData) { if (bookData) { this.setData(bookData): } // Some other initializations related to book }; Book.prototype = { setData: function(bookData) { angular.extend(this, bookData); }, delete: function() { $http.delete('ourserver/books/' + bookId); }, update: function() { $http.put('ourserver/books/' + bookId, this); }, getImageUrl: function(width, height) { return 'our/image/service/' + this.book.id + '/width/height'; }, isAvailable: function() { if (!this.book.stores || this.book.stores.length === 0) { return false; } return this.book.stores.some(function(store) { return store.quantity > 0; }); } }; return Book; }]);
现在,多个controller可以使用同一个booksManager服务。
app.controller('EditableBookController',['$scope', 'booksManager', function($scope, booksManager){ booksManager.getBook(1).then(function(book){ $scope.book = book; }) }]) .controller('BooksListController',['$scope', 'booksManager', function($scope, booksManager){ booksManager.loadAllBooks().then(function(books){ $scope.books = books; }) }])
P70系列延期,华为新旗舰将在下月发布
3月20日消息,近期博主@数码闲聊站 透露,原定三月份发布的华为新旗舰P70系列延期发布,预计4月份上市。
而博主@定焦数码 爆料,华为的P70系列在定位上已经超过了Mate60,成为了重要的旗舰系列之一。它肩负着重返影像领域顶尖的使命。那么这次P70会带来哪些令人惊艳的创新呢?
根据目前爆料的消息来看,华为P70系列将推出三个版本,其中P70和P70 Pro采用了三角形的摄像头模组设计,而P70 Art则采用了与上一代P60 Art相似的不规则形状设计。这样的外观是否好看见仁见智,但辨识度绝对拉满。