[转] Atlas与面向对象的Javascript

英文链接： http://atlas.asp.net/docs/atlas/doc/javascript/default.aspx

按我的理解，面向对象基本的特性无非六个字：封装、继承和多态。研究了Atlas的文档之后，发现它的Javascript脚本库把这几个特性都实现了。Ok, Let go......

先看看封装

Atlas提供了命名空间Namespace的功能来隔离命名冲突，而且在类中可以定义私有变量，达到的封装的目的。可惜的是类的方法好像只能是公共的。

以下是示例代码（所有的示例代码来自于原文链接）

Type.registerNamespace("Demo");

Demo.Person = function(firstName, lastName, emailAddress) {

var _firstName = firstName;

var _lastName = lastName;

var _emailAddress = emailAddress;

this.getFirstName = function() {

return _firstName;

}

this.getLastName = function() {

return _lastName;

}

this.getEmailAddress = function() {

return _emailAddress;

}

this.setEmailAddress = function(emailAddress) {

_emailAddress = emailAddress;

}

this.getName = function() {

return _firstName + ' ' + _lastName;

}

this.dispose = function() {

alert('bye ' + this.getName());

}

}

Demo.Person.registerClass('Demo.Person', null, Sys.IDisposable);

定义了以上的Demo.Person类之后，就可以在页面中的Javascript代码中按OO的方法使用了。

var testPerson = new Demo.Person('John', 'Smith', 'john.smith@example.com');

alert(testPerson.getFirstName() + " " + testPerson.getLastName() );

然后来看看继承

Demo.Person.prototype.sendMail = function() {

var emailAddress = this.getEmailAddress();

if (emailAddress.indexOf('@') < 0) {

emailAddress = emailAddress + '@example.com';

}

alert('Sending mail to ' + emailAddress + ' ');

}

Demo.Person.prototype.toString = function() {

return this.getName() + ' (' + this.getEmailAddress() + ')';

}

Demo.Employee = function(firstName, lastName, emailAddress, team, title) {

Demo.Employee.initializeBase(this, [firstName, lastName, emailAddress]);

var _team = team;

var _title = title;

this.getTeam = function() {

return _team;

}

this.setTeam = function(team) {

_team = team;

}

this.getTitle = function() {

return _title;

}

this.setTitle = function(title) {

_title = title;

}

}

Demo.Employee.registerClass('Demo.Employee', Demo.Person);

Demo.Employee.prototype.toString = function() {

return Demo.Employee.callBaseMethod(this, 'toString') + '\r\n' + this.getTitle() + '\r\n' + this.getTeam();

}

简单地说，就是用prototype定义虚函数。使用registerCalss定义基类，构造函数调用initializeBase

最后，我们来看看多态

其实上面的代码toString函数已经实现了继承的多态。我们再来看看接口实现的多态：

Type.registerNamespace("Demo.Animals");

Demo.Animals.IPet = function() {

this.returnFriendlyName = Function.abstractMethod;

}

Demo.Animals.IPet.registerInterface('Demo.Animals.IPet');

Demo.Animals.Animal = function(name) {

var _name = name;

this.returnName = function() {

return _name;

}

}

Demo.Animals.Animal.registerAbstractClass('Demo.Animals.Animal');

Demo.Animals.Animal.prototype.toStringCustom = function() {

return this.returnName();

}

Demo.Animals.Animal.prototype.speak = Function.abstractMethod;

Demo.Animals.Pet = function(name, friendlyName) {

Demo.Animals.Pet.initializeBase(this, [name]);

var _friendlyName = friendlyName;

this.returnFriendlyName = function() {

return _friendlyName;

}

}

Demo.Animals.Pet.registerAbstractClass('Demo.Animals.Pet', Demo.Animals.Animal, Demo.Animals.IPet);

Demo.Animals.Cat = function(friendlyName) {

Demo.Animals.Cat.initializeBase(this, ['Cat', friendlyName]);

}

Demo.Animals.Cat.registerClass('Demo.Animals.Cat', Demo.Animals.Pet);

Demo.Animals.Cat.prototype.speak = function() {

alert('meow');

}

Demo.Animals.Cat.prototype.toStringCustom = function() {

return 'Pet ' + Demo.Animals.Cat.callBaseMethod(this, 'toStringCustom');

}

Demo.Animals.Felix = function() {

Demo.Animals.Felix.initializeBase(this, ['Felix']);

}

Demo.Animals.Felix.registerClass('Demo.Animals.Felix', Demo.Animals.Cat);

Demo.Animals.Felix.prototype.toStringCustom = function() {

return Demo.Animals.Felix.callBaseMethod(this, 'toStringCustom') + ' its Felix!';

}

Demo.Animals.Dog = function(friendlyName) {

Demo.Animals.Dog.initializeBase(this, ['Dog', friendlyName]);

}

Demo.Animals.Dog.registerClass('Demo.Animals.Dog', Demo.Animals.Pet);

Demo.Animals.Dog.prototype.speak = function() {

alert('woof');

}

Demo.Animals.Tiger = function() {

Demo.Animals.Tiger.initializeBase(this, ['Tiger']);

}

Demo.Animals.Tiger.registerClass('Demo.Animals.Tiger', Demo.Animals.Animal);

Demo.Animals.Tiger.prototype.speak = function() {

alert('grrr');

}

首先，用registerInterface定义一个接口

然后，在registerClass的时候，第三个参数指定类实现了哪个接口

Atlas还支持抽象类的定义(registerAbstractClass)

确实算是比较完备了。

FROM: http://www.cnblogs.com/didasoft/archive/2006/03/30/362863.html