Java入门教程之图书管理系统（由简入繁）(六)

作者：AlexTan

E-mail: [email protected]

这次的代码主要是对上次的一些改进，具体修改了一些不可描述的BUG，和新增了几个查询方式，还把以前的Book类加了进来（这对以后返回给前端有用），废话不多说，直接贴代码！(注意：数据库的表的创建在：Java入门教程之图书管理系统（由简入繁）(五)  )

文件结构：

Operator.java:

package control;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;

import jdbc.database;
import model.Book;

public class Operator {
	
	public ArrayList getBookList()
	{
		ArrayList booklist = new ArrayList();
		Connection conn = null;
		Statement stmt = null;
		ResultSet rs = null;
		//3.通过数据库的连接操作数据库，实现增删改查
		try {
			conn = database.getConnection();
			stmt = conn.createStatement();
			rs = stmt.executeQuery("select id,bookname,author,price from book");//选择import java.sql.ResultSet;
			while(rs.next()){//如果对象中有数据，就会循环打印出来
				String bookname = rs.getString("bookname");
				String author = rs.getString("auhor");
				float price = rs.getFloat("price");
				Book book = new Book(bookname,author,price);
				booklist.add(book);
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			database.close(conn, stmt, rs);
		}
		return booklist;
	}
	
	public boolean addBook(String bookname,String author,float price)
	{
		Connection conn = null;
		Statement stmt = null;
		try {
			conn = database.getConnection();
			stmt = conn.createStatement();
			String sql = "insert into book(bookname,author,price) values('"+bookname+"','"+author+"',"+price+")";
			//System.out.println(sql);
			stmt.execute(sql);
			return true;
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return false;
		} finally {
			database.close(conn, stmt);
		}
	}
	
	public boolean deleteBook(int id,String bookname)
	{
		Connection conn = null;
		Statement stmt = null;
		try {
			conn = database.getConnection();
			stmt = conn.createStatement();
			String sql;
			if(id != -1)
			{
				sql = "delete from book where id ="+id;
			}
			else
			{
				sql = "delete from book where bookname ='"+bookname+"'";
			}
			if(stmt.execute(sql))
				return true;
			else
				return false;
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return false;
		} finally {
			database.close(conn, stmt);
		}
	}
	
	public boolean changeBoo(int id,String bookname,String changename)
	{
		Connection conn = null;
		Statement stmt = null;
		try {
			conn = database.getConnection();
			stmt = conn.createStatement();
			String sql;
			if (id != -1)
			{
				sql = "update book set bookname='"+changename+"'"+" where id="+id;
				//System.out.println(sql);
			}
			else
			{
				sql = "update book set bookname='"+changename+"'"+" where bookname='"+bookname+"'";
			}
			stmt.execute(sql);
			return true;
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return false;
		} finally {
			database.close(conn,stmt);
		}
	}
	
	public void findBoo(int id,String bookname,String author,String dimname,float minprice,float maxprice)
	{
		Connection conn = null;
		Statement stmt = null;
		ResultSet rs = null;
		try {
			conn = database.getConnection();
			stmt = conn.createStatement();
			String sql;
			if (id != -1)
			{
				sql = "select id,bookname,author,price from book"+" where id="+id;
				//System.out.println(sql);
			}
			else if(bookname != null)
			{
				sql = "select id,bookname,author,price from book"+" where bookname='"+bookname+"'";
			}
			else if(author != null)
			{
				sql = "select id,bookname,author,price from book"+" where author='"+author+"'";
			}
			else if(dimname != null)
			{
				sql = "select id,bookname,author,price from book"+" where bookname like'%"+dimname+"%'";
			}
			else if(maxprice != 0)
			{
				sql = "select id,bookname,author,price from book where price>="+minprice+" and price<="+maxprice;
			}
			else
			{
				System.out.println("出现未知错误，请联系管理员！");
				sql="";
			}
			rs = stmt.executeQuery(sql);
			if(rs.next())
			{
				System.out.println("查找成功！您查找的结果为：\n");
				do{//如果对象中有数据，就会循环打印出来
					System.out.println("编号："+rs.getInt("id")+" 书名："+rs.getString("bookname")+",作者："+rs.getString("author")+",价格："+rs.getFloat("price"));
				}while(rs.next());
			}
			else
				System.out.println("未查找到您想要的图书！");
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			database.close(conn, stmt, rs);
		}
	}
	
	
	public void printAllbook()
	{
		Connection conn = null;
		Statement stmt = null;
		ResultSet rs = null;
		//3.通过数据库的连接操作数据库，实现增删改查
		try {
			conn = database.getConnection();
			stmt = conn.createStatement();
			rs = stmt.executeQuery("select id,bookname,author,price from book");//选择import java.sql.ResultSet;
			if(rs.next())
			{
				do{//如果对象中有数据，就会循环打印出来
					System.out.println("编号："+rs.getInt("id")+" 书名："+rs.getString("bookname")+",作者："+rs.getString("author")+",价格："+rs.getFloat("price"));
				}while(rs.next());
			}
			else
			{
				System.out.println("图书库为空，请添加图书！");
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			database.close(conn, stmt, rs);
		}
	}
	
	public boolean clearBook()
	{
		Connection conn = null;
		Statement stmt = null;
		try {
			conn = database.getConnection();
			stmt = conn.createStatement();
			String sql = "truncate table book";
			stmt.execute(sql);
			return true;
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return false;
		} finally {
			database.close(conn, stmt);
		}
	}
}

database.java:

package jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class database {
	private static final String URL="jdbc:mysql://localhost:3306/books";
	private static final String NAME="root";
	private static final String PASSWORD="root";
	private static Connection conn=null;//静态代码块（将加载驱动、连接数据库放入静态块中）
	static{
		try {
				//1.加载驱动程序
				Class.forName("com.mysql.jdbc.Driver");
				//2.获得数据库的连接
				} catch (ClassNotFoundException e) {
					e.printStackTrace();
				}
			}
	
	//对外提供一个方法来获取数据库连接
	public static Connection getConnection(){
		try {
			conn = DriverManager.getConnection(URL, NAME, PASSWORD);
			//System.out.println("数据库连接成功！");
			return conn;
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return null;
		}
	}
	
	//断开数据库连接
	public static void close(Connection con, Statement stat, ResultSet rs)
	{
			try {
				if (rs != null)
					rs.close();
				if (stat != null)
					stat.close();
				if (con != null)
					con.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
	}
	//重载close函数，适用于没有ResultSet的情况
	public static void close(Connection con, Statement stat)
	{
		close(con,stat,null);
	}
}

Book.java:

package model;

public class Book {
	private String bookname;
	private String author;
	private float price;
	
	public Book(String bookname, String author, float price)
	{
		this.bookname = bookname;
		this.author = author;
		this.price = price;
	}

	public String getBookname() {
		return bookname;
	}

	public void setBookname(String bookname) {
		this.bookname = bookname;
	}

	public String getAuthor() {
		return author;
	}

	public void setAuthor(String author) {
		this.author = author;
	}

	public float getPrice() {
		return price;
	}

	public void setPrice(float price) {
		this.price = price;
	}

}

MainClass.java:

package ui;

import java.util.Scanner;

import control.Operator;

public class MainClass {
	
	public MainClass()
	{
		
		Scanner scan = new Scanner(System.in);
		
		while(true)
		{
			printMenu();
			
			//读取用户输入
			int choice = scan.nextInt();
			
			if(choice == 6)
			{
				System.out.println("成功退出系统，欢迎再次光临！");
				scan.close();
				break;
			}
			switch(choice)
			{
			case 1: addBook(); break;
			case 2: deleteBoo(); break;
			case 3: changeBoo(); break;
			case 4: findBoo(); break;
			case 5: clearBoo(); 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("清空图书...5");
		System.out.println("退出系统...6");	
	}
	
	void clearBoo()
	{
		Operator operator = new Operator();
		boolean isSuccess = operator.clearBook();
		if(isSuccess)
		{
			System.out.println("清空成功！");
		}
		else
		{
			System.out.println("清空失败！");
		}
	}
	
	void addBook()
	{
		while(true)
		{
			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();
			Operator operator = new Operator();
			boolean isSuccess = operator.addBook(bookname, author, price);
			if(isSuccess)
			{
				System.out.println("增加成功！");
			}
			else
			{
				System.out.println("增加失败！");
			}
			operator.printAllbook();
			System.out.println("是否继续增加？ y/n");
			char yno = scan.next().charAt(0);
			if (yno == 'y')
				continue;
			else
			{
				break;
			}
		}
	}
	
	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、编号/2、书名/3、返回主菜单");
			int choose = scan.nextInt();
			int id = -1;
			String name = "";
			if(choose == 1)
			{
				System.out.println("请输入要删除的书的编号：");
				id = scan.nextInt();
				Operator operator = new Operator();
				//System.out.println(id);
				if(id > -1)
				{
					boolean isSuccess = operator.deleteBook(id,name);
					if(isSuccess)
						System.out.println("删除成功！");
					else
						System.out.println("删除失败！请检查您输入的是否正确！");
					operator.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：");
				name = scan.next();
				Operator operator = new Operator();
				if(name != "")
				{
					boolean isSuccess = operator.deleteBook(id,name);
					if(isSuccess)
						System.out.println("删除成功！");
					else
						System.out.println("删除失败！");
					operator.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、编号/2、书名/3、返回主菜单");
			int choose = scan.nextInt();
			int id = -1;
			String name = "";
			if(choose == 1)
			{
				System.out.println("请输入要修改的书的编号：");
				id = scan.nextInt();
				Operator operator = new Operator();
				if(id > -1)
				{
					System.out.println("请输入你要修改为什么书名：");
					String str = scan.next();
					boolean isSuccess = operator.changeBoo(id,name,str);
					if(isSuccess)
						System.out.println("修改成功！");
					else
						System.out.println("修改失败！");
					
					operator.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：");
				name = scan.next();
				Operator operator = new Operator();
				if(name != "")
				{	
					System.out.println("请输入你要修改为什么书名：");
					String str = scan.next();
					boolean isSuccess = operator.changeBoo(id,name,str);
					if(isSuccess)
						System.out.println("修改成功！");
					else
						System.out.println("修改失败！");
					operator.printAllbook();
				}
			}
			else if(choose == 3)
			{
				printMenu();
				break;
			}
			else
			{
				System.out.println("输入非法！");
			}
		}
	}
	
	void findBoo()
	{
		Scanner scan = new Scanner(System.in);
		Operator operator = new Operator();
		while(true)
		{
			String name = null;
			int id = -1;
			String author = null;
			String dimname = null;
			float minprice = 0;
			float maxprice = -1;
			System.out.println("请输入按哪种方法查找图书：1、编号/2、书名(精确查找)/3、作者/4、书名(模糊查找)/5、价格/6、返回主菜单");
			int choose = scan.nextInt();
			if(choose == 1)
			{
				System.out.println("请输入要查找的书的编号：");
				id = scan.nextInt();
				if(id > -1)
				{
					operator.findBoo(id,name,author,dimname,minprice,maxprice);
				}
				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：");
				name = scan.next();
				if(name != "")
				{
					operator.findBoo(id,name,author,dimname,minprice,maxprice);
				}
				else
				{
					System.out.println("您的输入不能为空！");
				}
			}
			else if (choose == 3)
			{
				System.out.println("请输入您要查找的作者名：");
				author = scan.next();
				if(author != "")
				{
					operator.findBoo(id,name,author,dimname,minprice,maxprice);
				}
				else
				{
					System.out.println("您的输入不能为空！");
				}
			}
			else if (choose == 4)
			{
				System.out.println("请输入您要模糊查找的书名：");
				dimname = scan.next();
				if(dimname != "")
				{
					operator.findBoo(id,name,author,dimname,minprice,maxprice);
				}
				else
				{
					System.out.println("您的输入不能为空！");
				}
			}
			else if (choose == 5)
			{
				System.out.println("请输入您要查找的书的价格的最低价：");
				minprice = scan.nextFloat();
				System.out.println("请输入您要查找的书的价格的最高价：");
				maxprice = scan.nextFloat();
				if (maxprice>-1)
				{
					operator.findBoo(id,name,author,dimname,minprice,maxprice);
				}
				else
				{
					System.out.println("输入错误！");
				}
			}
			else if(choose == 6)
			{
				printMenu();
				break;
			}
			else
			{
				System.out.println("输入非法！");
			}
		}
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		new MainClass();
	}

}

好了，代码比较简单，就不一一说明了，主要就是增加了几个查询，修改了几个BUG，好了，就这样吧！

请期待下一篇：Java入门教程之图书管理系统（由简入繁）(七)

转载请注明出处：http://blog.csdn.net/alextan_/article/details/68489777