Java入门教程之图书管理系统（由简入繁）(三)

作者：AlexTan

E-mail: [email protected]

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 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)//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 block
			e.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;
		}
		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 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="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 stub
		new 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