Java入門教程之圖書管理系統（由簡入繁）(三)

作者：AlexTan

上一篇博客我們講到了用ArrayList來實現圖書管理系統，用ArrayList彌補了二中所提到的那兩個缺點。但是一個漏洞填完，又來了新的一個漏洞，所謂精益求精嘛。接下來我們就在原代碼的基礎上加上IO流，對TXT文件進行操作。

Java入門之圖書管理系統二(IO實現)：

這次的代碼只需要加上讀寫兩個函數就可以了，即load()和save()。

爲了代碼看起來不那麼臃腫，所以我們建立一個tool包，裏面放IO.java文件，這個文件的代碼具體如下：

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)//讀取文件
	{
		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 block
			e.printStackTrace();
		} catch (NumberFormatException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public void save(MainClass mainClass)//寫入文件
	{
		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 block
			e.printStackTrace();
		}
		
	}

}

然後在MainClass類裏的構造函數里加上

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

這兩段代碼就可以讀取了，在退出系統那裏，即

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

這裏改成這樣就好了，完整MainClass代碼如下：

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)
		{
			//讀取用戶輸入
			int choice = scan.nextInt();
			
			if(choice == 5)
			{
				io.save(this);
				System.out.println("成功退出系統，歡迎再次光臨！");
				break;
			}
			switch(choice)
			{
			case 1: addBook(); break;
			case 2: deleteBoo(); break;
			case 3: changeBoo(); break;
			case 4: findBoo(); break;
			default: System.out.println("輸入非法"); printMenu(); continue;
			}
		}
		
		
		/*
		while(true)
		{	
			//根據用戶輸入調用不同方法
			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("成功退出系統，歡迎再次光臨！");
				break;
			}
		}
		*/
	}
	void printMenu()
	{
		//打印菜單
		System.out.println("歡迎...");
		System.out.println("增加圖書...1");
		System.out.println("刪除圖書...2");
		System.out.println("修改圖書...3");
		System.out.println("查詢圖書...4");
		System.out.println("退出系統...5");	
	}
	
	void addBook()
	{
		if (count < booklist.size()+1)
		{
			System.out.println("當前共有:"+booklist.size()+"本書!");
			Scanner scan = new Scanner(System.in);
			System.out.println("請輸入圖書名：");
			String bookname = scan.next();
			System.out.println("請輸入作者：");
			String author = scan.next();
			System.out.println("請輸入單價：");
			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("圖書庫已滿！");
		}
		
		
	}
	
	void deleteBoo()
	{
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			System.out.println("請輸入按哪種方法刪除圖書：1、序號/2、書名/3、返回主菜單");
			int choose = scan.nextInt();
			if(choose == 1)
			{
				System.out.println("請輸入要刪除第幾本書：");
				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("刪除成功！");
					printAllBook();
				}
				else
				{
					System.out.println("輸入錯誤！");
				}
			}
			else if(choose == 2)
			{
				System.out.println("請輸入您要刪除的書名：");
				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("刪除成功！");
					printAllBook();
				}
				else
				{
						System.out.println("未查找到您想要的書名");
				}	
			}
			else if(choose == 3)
			{
				printMenu();
				break;
			}
			else
			{
				System.out.println("輸入非法！");
			}
		}
	}
	
	void changeBoo()
	{
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			System.out.println("請輸入按哪種方法修改圖書：1、序號/2、書名/3、返回主菜單");
			int choose = scan.nextInt();
			if(choose == 1)
			{
				System.out.println("請輸入要修改第幾本書：");
				int number = scan.nextInt();
				int id = orderFind(number);
				if(id > -1)
				{
					Book book = (Book)booklist.get(id);
					//System.out.println("原書名爲："+booklist[id].getBookname()+" 請輸入你要修改爲什麼書名：");
					System.out.println("原書名爲："+book.getBookname()+" 請輸入你要修改爲什麼書名：");
					String str = scan.next();
					System.out.println("請輸入作者：");
					String author = scan.next();
					System.out.println("請輸入單價：");
					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("輸入錯誤！");
				}
			}
			else if(choose == 2)
			{
				System.out.println("請輸入您要修改的書名：");
				String name = scan.next();
				int id = nameFind(name);
				if(id > -1)
				{
					Book book = (Book)booklist.get(id);
					//System.out.println("原書名爲："+booklist[id].getBookname()+" 請輸入你要修改爲什麼書名：");
					System.out.println("原書名爲："+book.getBookname()+" 請輸入你要修改爲什麼書名：");
					String str = scan.next();
					System.out.println("請輸入作者：");
					String author = scan.next();
					System.out.println("請輸入單價：");
					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("輸入非法！");
			}
		}
	}
	
	void findBoo()
	{
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			System.out.println("請輸入按哪種方法查找圖書：1、序號/2、書名/3、返回主菜單");
			int choose = scan.nextInt();
			if(choose == 1)
			{
				System.out.println("請輸入要查找第幾本書：");
				int number = scan.nextInt();
				int id = orderFind(number);
				if(id > -1)
				{
					Book book = (Book)booklist.get(id);
					//System.out.println("你要查找的書名爲："+booklist[id].getBookname()+" 作者："+booklist[id].getAuthor()+" 單價："+booklist[id].getPrice()+"元/本");
					System.out.println("你要查找的書名爲："+book.getBookname()+" 作者："+book.getAuthor()+" 單價："+book.getPrice()+"元/本");
				}
				else
				{
					System.out.println("輸入錯誤！");
				}
			}
			else if(choose == 2)
			{
				System.out.println("請輸入您要查找的書名：");
				String name = scan.next();
				int id = nameFind(name);
				if(id > -1)
				{
					Book book = (Book)booklist.get(id);
					//System.out.println("查找成功，您查找到的書爲第"+(id+1)+"本書！"+"書名爲："+booklist[id].getBookname()+" 作者："+booklist[id].getAuthor()+" 單價："+booklist[id].getPrice()+"元/本");	
					System.out.println("查找成功，您查找到的書爲第"+(id+1)+"本書！"+"書名爲："+book.getBookname()+" 作者："+book.getAuthor()+" 單價："+book.getPrice()+"元/本");	
				}
			}
			else if(choose == 3)
			{
				printMenu();
				break;
			}
			else
			{
				System.out.println("輸入非法！");
			}
		}
	}
	
	void printAllBook()
	{
		for (int i = 0; i < count; i++)
		{
			Book book = (Book)booklist.get(i);
			//System.out.println("第"+(i+1)+"本書名："+booklist[i].getBookname()+" 作者："+booklist[i].getAuthor()+" 單價："+booklist[i].getPrice()+"元/本");
			System.out.println("第"+(i+1)+"本書名："+book.getBookname()+" 作者："+book.getAuthor()+" 單價："+book.getPrice()+"元/本");
		}
	}
	
	int orderFind(int number)
	{
		//System.out.println(number);
		if(number <= count)
		{
			int id = number - 1;
			return id;
		}
		else
			return -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("未查找到您想要的書名");
				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 block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.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="書名："+ bookname +" 作者:"+author+" 價格:"+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 stub
		new MainClass();
	}

}

總結：

這樣下來，便解決了重新運行程序數據消失的問題了。雖然我們上面把對txt文件讀寫的函數寫在了tool包下的IO類裏，但是整個程序看起來還是非常的臃腫，代碼不好維護，也不好閱讀，因此接下來我們將把以上代碼改成MVC的編程模式，來讓代碼顯得更系統化。

請閱讀下一篇：Java入門教程之圖書管理系統（由簡入繁）(四)

轉載請註明出處：http://blog.csdn.net/alextan_/article/details/65449952

Java入門教程之圖書管理系統（由簡入繁）(三)

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Java入門教程之圖書管理系統（由簡入繁）(三)

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