详解angularjs利用ui-route异步加载组件

ui-route相比于angularjs的原生视图路由更好地支持了路由嵌套，状态转移等等。随着视图不断增加，打包的js体积也会越来越大，比如我在应用里面用到了wangeditor里面单独依赖的jquery就300多k。异步加载各个组件就很有必要。在这里我就以ui-route为框架来进行异步加载说明。

首先看一下路由加载文件

angular.module('webtrn-sns').config(['$stateProvider', function ($stateProvider) {
$stateProvider.state({
name: 'home.message',
url: '/message',
abstract: true,
templateProvider: ['resources', function (resources) {
return resources.template
}],
controllerProvider: ['resources', (resources)=> {
return resources.controller
}],
onEnter: ['resources', (resources)=>resources.css.use()],
onExit: ['resources', (resources)=>resources.css.unuse()],
resolve: {
resources: ()=> {
return new Promise(
resolve => {
require([], () => {
resolve({
css: require('./css/message_box.css'),
template: require('./html/message_box.html'),
controller: require('./js/message_box.js')
})
})
}
);
}
}
}
).state({
name: 'home.message.add_message',
url: '/add_message?isReply&toUid&title',
params: {isReply: null, toUid: null, title: null},
templateProvider: ['resources', function (resources) {
return resources.template
}],
controllerProvider: ['resources', (resources)=> {
return resources.controller
}],
onEnter: ['resources', (resources)=>resources.css.use()],
onExit: ['resources', (resources)=>resources.css.unuse()],resolve: {
resources: ()=> {
return new Promise(
resolve => {
require(['./js/message.js'], () => {
resolve({
css: require('./css/add_message.css'),
template: require('./html/add_message.html'),
controller: require('./js/add_message.js')
})
})
}
);
}
}}
)
}])

这个是路由状态的一个声明文件，name,url,param字段的方式不变，关键是看resolve这个部分。根据ui-route的resolve文档,resolve是为了给state或者controller进行自定义注入对象的。

下面是举出文档中关于resolve的例子：

$stateProvider.state('myState', {
resolve:{
// Example using function with simple return value.
// Since it's not a promise, it resolves immediately.
simpleObj: function(){
return {value: 'simple!'};
},
// Example using function with returned promise.
// This is the typical use case of resolve.
// You need to inject any services that you are
// using, e.g. $http in this example
promiseObj: function($http){
// $http returns a promise for the url data
return $http({method: 'GET', url: '/someUrl'});
},
// Another promise example. If you need to do some
// processing of the result, use .then, and your
// promise is chained in for free. This is another
// typical use case of resolve.
promiseObj2: function($http){
return $http({method: 'GET', url: '/someUrl'})
.then (function (data) {
return doSomeStuffFirst(data);
});
},
// Example using a service by name as string.
// This would look for a 'translations' service
// within the module and return it.
// Note: The service could return a promise and
// it would work just like the example above
translations: "translations",
// Example showing injection of service into
// resolve function. Service then returns a
// promise. Tip: Inject $stateParams to get
// access to url parameters.
translations2: function(translations, $stateParams){
// Assume that getLang is a service method
// that uses $http to fetch some translations.
// Also assume our url was "/:lang/home".
return translations.getLang($stateParams.lang);
},
// Example showing returning of custom made promise
greeting: function($q, $timeout){
var deferred = $q.defer();
$timeout(function() {
deferred.resolve('Hello!');
}, 1000);
return deferred.promise;
}
},
// The controller waits for every one of the above items to be
// completely resolved before instantiation. For example, the
// controller will not instantiate until promiseObj's promise has
// been resolved. Then those objects are injected into the controller
// and available for use.
controller: function($scope, simpleObj, promiseObj, promiseObj2, translations, translations2, greeting){
$scope.simple = simpleObj.value;
// You can be sure that promiseObj is ready to use!
$scope.items = promiseObj.data.items;
$scope.items = promiseObj2.items;
$scope.title = translations.getLang("english").title;
$scope.title = translations2.title;
$scope.greeting = greeting;
}
})

我们可以看到resolve的对象是支持Promise的。

再回到我们之前的代码templateProvider和controllerProvider我们注入了resources的模板对象和controller对象，onEnter和onExit注入了css模块。

如果controller中依赖了服务怎么办的？

resolve: {
resources: ()=> {
return new Promise(
resolve => {
require(['./js/message.js'], () => {
resolve({
css: require('./css/add_message.css'),
template: require('./html/add_message.html'),
controller: require('./js/add_message.js')
})
})
}
);
}
}

可以在require里面将服务注入，如代码中的message.js。而为了将服务进行异步加载我们不能用普通的.factory或者.service。而需要调用$provide.factory或者$provide.service

如果采用webpack进行编译打包的话就需要webpack.optimize.CommonsChunkPlugin的支持，这样可以对js进行拆分打包，达到异步加载js的目的。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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