Java入门教程之图书管理系统（由简入繁）(三)

作者：AlexTan

E-mail: [e-mail]

上一篇博客我们讲到了用ArrayList来实现图书管理系统，用ArrayList弥补了二中所提到的那两个缺点。但是一个漏洞填完，又来了新的一个漏洞，所谓精益求精嘛。接下来我们就在原代码的基础上加上IO流，对TXT文件进行操作。

Java入门之图书管理系统二(IO实现)：

这次的代码只需要加上读写两个函数就可以了，即load()和save()。

为了代码看起来不那么臃肿，所以我们建立一个tool包，里面放IO.java文件，这个文件的代码具体如下：

package tool;import java.io.BufferedReader;import java.io.File;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import java.util.ArrayList;import model.Book;import ui.MainClass;public class IO {public void load(MainClass mainClass)//读取文件{try {String filename = "D:\\Users\\alext\\workspace\\first\\book.txt";//也可以用d:/xxx/xxx的形式File file = new File(filename);BufferedReader reader = new BufferedReader(new FileReader(file));String temp;while((temp = reader.readLine()) != null){String bookname = temp.split(",")[0];String author = temp.split(",")[1];String pricestr = temp.split(",")[2];float price = Float.parseFloat(pricestr);Book book = new Book(bookname,author,price);mainClass.booklist.add(book);mainClass.count++;}reader.close();} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (NumberFormatException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void save(MainClass mainClass)//写入文件{String fileName = "D:\\Users\\alext\\workspace\\first\\book.txt";String allbook="";for(int i = 0; i < mainClass.booklist.size(); i++){Book book = (Book)mainClass.booklist.get(i);String temp = book.getBookname() + "," + book.getAuthor() + "," + book.getPrice() + "\r\n";allbook += temp;}try {File file1 = new File(fileName);FileWriter fileWriter;fileWriter = new FileWriter(file1);fileWriter.write(allbook);fileWriter.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

然后在MainClass类里的构造函数里加上

IO io = new IO(); io.load(this);

这两段代码就可以读取了，在退出系统那里，即

if(choice == 5){io.save(this);System.out.println("成功退出系统，欢迎再次光临！");break;}

这里改成这样就好了，完整MainClass代码如下：

package ui;import java.util.ArrayList;import java.util.Scanner;import model.Book;import tool.IO;public class MainClass {/*public static final int SIZE = 10;Book[] booklist = new Book[SIZE];*/public ArrayList booklist = new ArrayList();public int count = 0;public MainClass(){Scanner scan = new Scanner(System.in);IO io = new IO(); io.load(this);printMenu();while(true){//读取用户输入int choice = scan.nextInt();if(choice == 5){io.save(this);System.out.println("成功退出系统，欢迎再次光临！");break;}switch(choice){case 1: addBook(); break;case 2: deleteBoo(); break;case 3: changeBoo(); break;case 4: findBoo(); break;default: System.out.println("输入非法"); printMenu(); continue;}}/*while(true){//根据用户输入调用不同方法if(choice == 1){addBook();}else if(choice == 2){deleteBoo();}else if(choice == 3){changeBoo();}else if(choice == 4){findBoo();}else if(choice == 5){System.out.println("成功退出系统，欢迎再次光临！");break;}}*/}void printMenu(){//打印菜单System.out.println("欢迎...");System.out.println("增加图书...1");System.out.println("删除图书...2");System.out.println("修改图书...3");System.out.println("查询图书...4");System.out.println("退出系统...5");}void addBook(){if (count < booklist.size()+1){System.out.println("当前共有:"+booklist.size()+"本书!");Scanner scan = new Scanner(System.in);System.out.println("请输入图书名：");String bookname = scan.next();System.out.println("请输入作者：");String author = scan.next();System.out.println("请输入单价：");float price = scan.nextFloat();Book book = new Book(bookname,author,price);//booklist[count] = book;booklist.add(book);count++;System.out.println("增加成功！");printAllBook();}else{System.out.println("图书库已满！");}}void deleteBoo(){Scanner scan = new Scanner(System.in);while(true){System.out.println("请输入按哪种方法删除图书：1、序号/2、书名/3、返回主菜单");int choose = scan.nextInt();if(choose == 1){System.out.println("请输入要删除第几本书：");int id = scan.nextInt();id = orderFind(id);//System.out.println(id);if(id > -1){/*for(int i = id; i < count - 1 ; i++)booklist[i]=booklist[i+1];*/booklist.remove(id);count--;System.out.println("删除成功！");printAllBook();}else{System.out.println("输入错误！");}}else if(choose == 2){System.out.println("请输入您要删除的书名：");String name = scan.next();int id = nameFind(name);if(id > -1){/*for(int j = id; j<count-1; j++){booklist[j]=booklist[j+1];}*/booklist.remove(id);count --;System.out.println("删除成功！");printAllBook();}else{System.out.println("未查找到您想要的书名");}}else if(choose == 3){printMenu();break;}else{System.out.println("输入非法！");}}}void changeBoo(){Scanner scan = new Scanner(System.in);while(true){System.out.println("请输入按哪种方法修改图书：1、序号/2、书名/3、返回主菜单");int choose = scan.nextInt();if(choose == 1){System.out.println("请输入要修改第几本书：");int number = scan.nextInt();int id = orderFind(number);if(id > -1){Book book = (Book)booklist.get(id);//System.out.println("原书名为："+booklist[id].getBookname()+" 请输入你要修改为什么书名：");System.out.println("原书名为："+book.getBookname()+" 请输入你要修改为什么书名：");String str = scan.next();System.out.println("请输入作者：");String author = scan.next();System.out.println("请输入单价：");float price = scan.nextFloat();//booklist[id].setBook(str,author,price);book.setBook(str,author,price);System.out.println("修改成功！");printAllBook();}else{System.out.println("输入错误！");}}else if(choose == 2){System.out.println("请输入您要修改的书名：");String name = scan.next();int id = nameFind(name);if(id > -1){Book book = (Book)booklist.get(id);//System.out.println("原书名为："+booklist[id].getBookname()+" 请输入你要修改为什么书名：");System.out.println("原书名为："+book.getBookname()+" 请输入你要修改为什么书名：");String str = scan.next();System.out.println("请输入作者：");String author = scan.next();System.out.println("请输入单价：");float price = scan.nextFloat();//booklist[id].setBook(str,author,price);book.setBook(str,author,price);System.out.println("修改成功！");printAllBook();}}else if(choose == 3){printMenu();break;}else{System.out.println("输入非法！");}}}void findBoo(){Scanner scan = new Scanner(System.in);while(true){System.out.println("请输入按哪种方法查找图书：1、序号/2、书名/3、返回主菜单");int choose = scan.nextInt();if(choose == 1){System.out.println("请输入要查找第几本书：");int number = scan.nextInt();int id = orderFind(number);if(id > -1){Book book = (Book)booklist.get(id);//System.out.println("你要查找的书名为："+booklist[id].getBookname()+" 作者："+booklist[id].getAuthor()+" 单价："+booklist[id].getPrice()+"元/本");System.out.println("你要查找的书名为："+book.getBookname()+" 作者："+book.getAuthor()+" 单价："+book.getPrice()+"元/本");}else{System.out.println("输入错误！");}}else if(choose == 2){System.out.println("请输入您要查找的书名：");String name = scan.next();int id = nameFind(name);if(id > -1){Book book = (Book)booklist.get(id);//System.out.println("查找成功，您查找到的书为第"+(id+1)+"本书！"+"书名为："+booklist[id].getBookname()+" 作者："+booklist[id].getAuthor()+" 单价："+booklist[id].getPrice()+"元/本");System.out.println("查找成功，您查找到的书为第"+(id+1)+"本书！"+"书名为："+book.getBookname()+" 作者："+book.getAuthor()+" 单价："+book.getPrice()+"元/本");}}else if(choose == 3){printMenu();break;}else{System.out.println("输入非法！");}}}void printAllBook(){for (int i = 0; i < count; i++){Book book = (Book)booklist.get(i);//System.out.println("第"+(i+1)+"本书名："+booklist[i].getBookname()+" 作者："+booklist[i].getAuthor()+" 单价："+booklist[i].getPrice()+"元/本");System.out.println("第"+(i+1)+"本书名："+book.getBookname()+" 作者："+book.getAuthor()+" 单价："+book.getPrice()+"元/本");}}int orderFind(int number){//System.out.println(number);if(number <= count){int id = number - 1;return id;}elsereturn -1;}int nameFind(String name){int id = -1;for(int i = 0; i < count; i++){Book book = (Book)booklist.get(i);//if(booklist[i].getBookname().equals(name))if(book.getBookname().equals(name)){id = i;break;}else if(i<count)continue;else{System.out.println("未查找到您想要的书名");break;}}return id;}/*void load(){String fileName = "D:/Users/alext/workspace/first/book.txt";try {File file = new File(fileName);BufferedReader in = new BufferedReader(new FileReader(file));String tempString;while ((tempString = in.readLine()) != null){System.out.println(tempString);}in.close();} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}void save(String bookname,String author,float price){String fileName = "D:\\Users\\alext\\workspace\\first\\book.txt";File file1 = new File(fileName);        try {        FileWriter fileWriter = new FileWriter(file1,true);    String writeData="书名："+ bookname +" 作者:"+author+" 价格:"+price+"元/本 \n";    fileWriter.write(writeData);    fileWriter.close();    } catch (IOException e) {    // TODO Auto-generated catch block    e.printStackTrace();    } }*/public static void main(String[] args) {// TODO Auto-generated method stubnew MainClass();}}

总结：

这样下来，便解决了重新运行程序数据消失的问题了。虽然我们上面把对txt文件读写的函数写在了tool包下的IO类里，但是整个程序看起来还是非常的臃肿，代码不好维护，也不好阅读，因此接下来我们将把以上代码改成MVC的编程模式，来让代码显得更系统化。

请阅读下一篇：Java入门教程之图书管理系统（由简入繁）(四)

转载请注明出处：http://blog.csdn.net/alextan_/article/details/65449952