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<head>
<title>javascript高级语法20-责任链模式</title>
</head>
<body>
<script>
/*责任链模式
* 消除发送者与接收者之间的耦合。
* 1.责任链的发送者知道链的入口是谁
* 2.每一个链节点知道自己的下一个节点是谁
* 3.每一个链的传入和传出值是一样的；
*/ //扩展filter函数
Function.prototype.method = function(name,fn){
this.prototype[name] = fn;
return this;
}
if(!Array.prototype.filter){
Array.method("filter",function(fn,obj){
var scope = this.Obj || window;
var a = [];
for(var i=0;i<this.length;i++){
if(!fn.call(scope,this[i],i,this)){
continue;
}
a.push(this[i]);
}
//返回过滤好的数据
return a;
})
} function demo(){
//扩展window
window.setSuccessor = function(after,before){
after.successor = before;
}
//用于拷贝字符串的方法 20*"-" = "------------------"
window.copyStr = function(num,str){
var newStr = '';
for(var i=0;i<num;i++){
newStr += str;
}
return newStr;
}
//转换数组中的对象为字符串
var showStr = function(arr){
var newStr = "";
for(var i=0;i<arr.length;i++){
newStr += JSON.stringify(arr[i]);
}
return newStr;
} //书店找书和加书两个需求
//用户可以输入关键字找书（书号，作者，名称）
//不同书架管理员管理自己的书籍添加任务 //图书类
var Book = function(id,name,author,type){
this.id = id;
this.name = name;
this.author = author;
this.type = type;
}
//书店
var myBookShop = (function(){
//书架
var jsBooks = new Array(); //JS书架
var cBooks = new Array(); //C语言书架
var pythonBooks = new Array(); //python书架
//内部类1
function addJSBook(book){
if(book.type == "js"){
jsBooks.push(book);
}else{
//负责传递到下一个功能
addJSBook.successor(book);
}
}
//内部类2
function addPythonBook(book){
if(book.type == "py"){
pythonBooks.push(book);
}else{
//负责传递到下一个功能
addPythonBook.successor(book);
}
}
//内部类3
function addCBook(book){
if(book.type == "c"){
cBooks.push(book);
}else{
//负责传递到下一个功能
addCBook.successor(book);
}
}
//设置责任链
setSuccessor(addJSBook,addPythonBook);
setSuccessor(addPythonBook,addCBook); //查询书籍
var bookList = null;
function findBookById(keyword){
if(!bookList){
bookList = jsBooks.concat(cBooks).concat(pythonBooks);
}
var book = new Array();
book = bookList.filter(function(book){
if(book.id.indexOf(keyword) != -1){
return true;
}else{
return false;
}
});
//进行链式查询
return book.concat(findBookById.successor(keyword,book));
}
function findBookByName(keyword,book){
book = bookList.filter(function(book){
if(book.name.indexOf(keyword) != -1){
return true;
}else{
return false;
}
});
return book;
}
//规划责任链
setSuccessor(findBookById,findBookByName); //真正的图书馆类
return function(){
this.addBook = function(book){
if(book instanceof Book){
//因为我知道谁是链的入口。可以这么写
addJSBook(book);
}
}
this.findBook = function(keyword){
return findBookById(keyword);
}
this.showBooks = function(){
//document.write("c语言类图书"+cBooks.toSource()+"<br>")
//这里的toSource()方法只有火狐支持,所以我全局定义了showStr方法
document.write("js类图书"+showStr(jsBooks)+"<br>")
document.write("c语言类图书"+showStr(cBooks)+"<br>")
document.write("Python类图书"+showStr(pythonBooks)+"<br>")
document.write(copyStr(60,"-")+"<br>");
}
}
})();
//添加book
var pb = new myBookShop();
pb.addBook(new Book("00101","Extjs","zhangsan","js"));
pb.addBook(new Book("00102","cprimer","jim","js"));
pb.addBook(new Book("00103","c#","chance","c"));
pb.addBook(new Book("00201","c++","chance","c"));
pb.addBook(new Book("00202","python","py","py"));
pb.addBook(new Book("00203","py实战","杨国正","py"));
//展示
pb.showBooks();
//查询
document.write(showStr(pb.findBook("02"))+"<br>");
document.write(copyStr(60,"-")+"<br>");
document.write(showStr(pb.findBook("c")));
}
demo();
</script>
</body>
</html>