面向对象的Javascript之三(封装和信息隐藏)_js面向对象

var Publication = new Interface("Publication", ["getIsbn", "setIsbn", "getTitle", "setTitle", "getAuthor", "setAuthor", "display"]);
var Book = (function() {
// private static attribute
var numsOfBooks = 0;
// private static contant
var Constants = {
"MAX_JAVASCRIPT_NUMS": 500,
"MAX_NET_NUMS": 1000
};
// private static previleged method
this.getMaxNums(name) {
return Constants[name.ToUpperCase()];
}
// private static method
function checkIsbn(isbn) {
if(isbn == undefined || typeof isbn != "string") return false;
isbn = isbn.replace("-", "");
if(isbn.length != 10 && isbn.length != 13) return false;
var sum = 0;
if(isbn.length == 10) {
if(!isbn.match(\^\d{9}\)) return false;
for(var i = 0;i < 9;i++) {
sum += isbn.charAt(i) * (10 - i);
}
var checksum = sum % 11;
if(checksum == 10) checksum = "X";
if(isbn.charAt(9) != checksum) return false;
} else {
if(!isbn.match(\^\d{12}\)) return false;
for(var i = 0;i < 12;i++) {
sum += isbn.charAt(i) * (i % 2 == 0 ? 1 : 3);
}
var checksum = sum % 10;
if(isbn.charAt(12) != checksum) return false;
}
return true;
}
// return constructor
return function(newIsbn, newTitle, newAuthor) {
// private attribute
var isbn, title, author;
// previleged method
this.getIsbn = function() {
return isbn;
};
this.setIsbn = function(newIsbn) {
if(!Book.checkIsbn(newIsbn)) {
throw new Error("Book: Invalid ISBN.");
}
isbn = newIsbn;
}
this.getTitle = function() {
return title;
},
this.setTitle = function(newTitle) {
title = newTitle || "";
},
this.getAuthor = function() {
return author;
},
this.setAuthor = function(newAuthor) {
author = newAuthor || "";
}
Book.numsOfBooks++;
if(Book.numsOfBooks > 50) {
throw new Error("Book: at most 50 instances of Book can be created.");
}
// implements Publication interface
this.setIsbn(newIsbn);
this.setTitle(newTitle);
this.setAuthor(newAuthor);
};
})();
// public static methods
Book.convertToTitle = function(title) {
return title.toUpperCase();
}
// public methods
Book.prototype = {
display: function() {
return "Book: ISBN: " + this.getIsbn() + ",Title: " + this.getTitle() +
",Author: " + this.getAuthor() + ", Maximum: ";
},
showMaxNums: function() {
return Book.getMaxNums("MAX_JAVASCRIPT_NUMS");
}
};