JavaScript数据结构与算法——列表详解（下），基于Nodejs实现一个列表应用

1、上篇回顾：

上篇我们实现了一个列表类，并添加了一些属性，实现了比较多的方法，本文章将与大家一起使用列表实现一个图书借阅查询系统。需要使用JavaScript数据结构与算法——列表详解（上）中写好的列表类List(）。

如需查看List()类代码说明，请查阅本人列表上篇讲解，这里只给出List的源码，以供接下来写调用：

 function List() {this.listSize = 0this.pos = 0this.dataStore = [] // 初始化一个用于保存列表元素的空数组this.clear = clearthis.find = findthis.toString = toStringthis.insert = insertthis.append = appendthis.remove = removethis.front = frontthis.end = endthis.prev = prevthis.next = nextthis.hasNext = hasNextthis.hasPrev = hasPrevthis.length = lengththis.currPos = currPosthis.moveTo = moveTothis.getElement = getElementthis.contains = contains}function append(element) {this.dataStore[this.listSize++] = element}function find(element) {for (var i = 0; i < this.dataStore.length; i++) {if (this.dataStore[i] == element) {return i}}return -1}function remove(element) {var foundAt = this.find(element)if (foundAt > -1) {this.dataStore.splice(foundAt, 1)this.listSize--return true}return false}function length() {return this.listSize}function toString() {return this.dataStore.toString()}function insert(element, after) {var insertPos = this.find(after)if (insertPos > -1) {this.dataStore.splice(insertPos + 1, 0, element)this.liseSize++return true}return false}function clear() {delete this.dataStorethis.dataStore.length = 0this.listSize = 0this.pos = 0}function contains(element) {for (var i = 0; i < this.dataStore.length; i++) {return true}return false}// 遍历列表function front() {this.pos = 0}function end() {this.pos = this.listSize - 1}function prev() {this.pos--}function next() {if (this.pos < this.listSize) {this.pos++}}function currPos() {return this.pos}function moveTo(position) {this.pos = position}function hasNext() {return this.pos < this.listSize}function hasPrev() {return this.pos >= 0}function getElement() {return this.dataStore[this.pos]}

2、基于Nodejs使用列表实现一个图书借阅查询系统

新建一个List文件夹，里边包含一个book.txt（用于存放书本），一个book.js，用于编写js（请先载入上篇中实现的List()相关代码）。

2.1 读取书本文件

 // Created by xiaoqiang on 05/04/2018.
var fs = require('fs')
function readBooks('book.txt') {var data = fs.readFileSync(file)var dataArray = data.toString().split('\n')for (var i = 0; i < dataArray.length; i++) {dataArray[i] = dataArray[i].trim()}return dataArray
}

编写的过程可以在函数外添加console.log(readBooks('book.txt'))，便于测试，进入当前文件夹，使用命令node book.js，看到以下结果证明node环境没问题&&函数编写没问题：

2.2 保存书本到列表

开头我们说过，上篇中我们写好了一个List()类，接下来我们通过此类创建一个书本列表对象，并往列表对象中的dataStore属性添加元素。

function saveBooksToList(file) {var booksArray = readBooks(file)for (var i = 0; i < booksArray.length; i++) {bookList.append(booksArray[i])}
}

2.3 展示列表信息

function displayList(list) {for (list.front(); list.currPos() < list.length(); list.next()) {console.log(list.getElement())}
}

测试：

 var bookList = new List()saveBooksToList('book.txt')displayList(bookList)

运行结果：

2.4 创建借阅人方法

此方法用于保存哪个人借阅了哪些书。

// 借阅人信息
function borrower(name, book) {this.name = namehis.book = book
}

2.5 实现借书方法

// 借书
function borrowBook(name, book, bookList, borrowerList) {if (bookList.contains(book)) {var b = new borrower(name, book)borrowerList.append(b)bookList.remove(book)console.log(name + '借阅书本' + book + '成功!!!')} else {console.log('书本已经被借走!!!')}
}

解释：四个参数意义分别为：借阅人名称，要借的书本，书本列表，借阅人列表；首先检查书本是否存在，存在的话将书本及借阅人信息保存到借阅人列表，信息如果不存在提示错误信息。

2.6 最终结果测试

 // 书本列表对象var bookList = new List()// 借阅人列表对象var borrowerList = new List()// 保存书本到列表saveBooksToList('book.txt')console.log('------------当前可借的书-------------------')// 显示书本信息displayList(bookList)console.log('-----------------开始借书------------------')// 借书borrowBook('xgq', 'Nodejs详解', bookList, borrowerList)console.log('-----------------借阅信息------------------')// 显示借阅人列表displayList(borrowerList)console.log('-----------------剩余可借的书---------------')
// 借阅后剩余的书本列表displayList(bookList)

结果：

2.7 book.js完整代码（整合上篇）：

 // Created by xiaoqiang on 05/04/2018.var fs = require('fs')var readline = require('readline')
// JavaScript数据结构与算法——列表详解(上)function List() {this.listSize = 0this.pos = 0this.dataStore = [] // 初始化一个用于保存列表元素的空数组this.clear = clearthis.find = findthis.toString = toStringthis.insert = insertthis.append = appendthis.remove = removethis.front = frontthis.end = endthis.prev = prevthis.next = nextthis.hasNext = hasNextthis.hasPrev = hasPrevthis.length = lengththis.currPos = currPosthis.moveTo = moveTothis.getElement = getElementthis.contains = contains}function append(element) {this.dataStore[this.listSize++] = element}function find(element) {for (var i = 0; i < this.dataStore.length; i++) {if (this.dataStore[i] == element) {return i}}return -1}function remove(element) {var foundAt = this.find(element)if (foundAt > -1) {this.dataStore.splice(foundAt, 1)this.listSize--return true}return false}function length() {return this.listSize}function toString() {return this.dataStore.toString()}function insert(element, after) {var insertPos = this.find(after)if (insertPos > -1) {this.dataStore.splice(insertPos + 1, 0, element)this.liseSize++return true}return false}function clear() {delete this.dataStorethis.dataStore.length = 0this.listSize = 0this.pos = 0}function contains(element) {for (var i = 0; i < this.dataStore.length; i++) {return true}return false}// 遍历列表方法function front() {this.pos = 0}function end() {this.pos = this.listSize - 1}function prev() {this.pos--}function next() {if (this.pos < this.listSize) {this.pos++}}function currPos() {return this.pos}function moveTo(position) {this.pos = position}function hasNext() {return this.pos < this.listSize}function hasPrev() {return this.pos >= 0}function getElement() {return this.dataStore[this.pos]}// 读取书本文件function readBooks(file) {var data = fs.readFileSync(file)var dataArray = data.toString().split('\n')for (var i = 0; i < dataArray.length; i++) {dataArray[i] = dataArray[i].trim()}return dataArray
}
// 保存书本到列表
function saveBooksToList(file) {var booksArray = readBooks(file)for (var i = 0; i < booksArray.length; i++) {bookList.append(booksArray[i])}
}
// 展示列表信息
function displayList(list) {for (list.front(); list.currPos() < list.length(); list.next()) {console.log(list.getElement())}
}// 借阅人信息
function borrower(name, book) {this.name = namethis.book = book
}// 借书
function borrowBook(name, book, bookList, borrowerList) {if (bookList.contains(book)) {var b = new borrower(name, book)borrowerList.append(b)bookList.remove(book)console.log(name + '借阅书本' + book + '成功!!!')} else {console.log('书本已经被借走!!!')}
}
// 测试// 书本列表对象var bookList = new List()// 借阅人列表对象var borrowerList = new List()// 保存书本到列表saveBooksToList('book.txt')console.log('------------当前可借的书-------------------')// 显示书本信息displayList(bookList)console.log('-----------------开始借书------------------')// 借书borrowBook('xgq', 'Nodejs详解', bookList, borrowerList)console.log('-----------------借阅信息------------------')// 显示借阅人列表displayList(borrowerList)console.log('-----------------剩余可借的书---------------')
// 借阅后剩余的书本列表displayList(bookList)

有错误欢迎指出，谢谢。

完结~~