[Java]---图书管理系统（五）

其他 2019-02-22 11:51:09 阅读次数: 0

参考：http://blog.csdn.net/alextan_/article/details/65447446

本系列是通过学习AlexTan这位博主的文章搭建一个图书管理系统，顺便再学习一下java这门语言。大二水了一学期java课，完全是菜鸡，所以注释很多自己的理解。

这篇文章要解决的是将数据存储到数据库中，数据库选用mysql。

一、创建数据库

create database books;
use books;
create table book(id int(6) primary key not null auto_increment,bookname varchar(255),author varchar(255),price float);

这是在mysql中创建

二、项目目录
在这里插入图片描述
三、Database.java
知识点–JDBC
1.加载驱动
首先要下载数据库的驱动jar文件，下载的版本要和自己的数据库版本对应，下载地址：https://dev.mysql.com/downloads/connector/j/
2.获取数据库连接
使用java.sql.DriverManager的getConnection(String url, String user, String pass)方法获取数据库连接Connectiond对象
3.通过Connection创建statement对象
通常有三种statement对象

  • createStatement（），创建普通statement对象，可以直接执行sql语句
  • prepareStatement（String sql），创建预编译的statement对象，支持SQL语句带参数
  • prepareCall（String sql），创建能执行存储过程的statement对象
    4.执行SQL语句，所有statement对象都有三个执行sql的方法
  • execute（）可执行任何SQL语句返回Boolean，表示是否返回了数据，需要通过statement对象的getResultSet（）方法才能获取结果集，通过statement的getUpdateCount（）获得影响的条数。
  • executeQuery（）返回ResultSet结果集
  • executeUpdate（）执行SQL语句返回受影响的条数

参考：https://www.cnblogs.com/fysola/p/6150686.html

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?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8&useSSL=false";
	private static final String NAME="root";
	private static final String PASSWORD="pass993.";
	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 {
			//加载驱动程序
			Class.forName("com.mysql.cj.jdbc.Driver");
		}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);
			return conn;
		}catch(SQLException e) {
			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) {
			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);
	}
}

四、Operator.java
修改图书和删除图书还是有bug。如果输入不存在的id号还是会显示修改成功但是其实什么都没改。

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<Book> getBookList()
	{
		ArrayList<Book> booklist = new ArrayList<Book>();
		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+"'";
			}
			stmt.execute(sql); 
			return true;
		} catch (SQLException e) {
			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);
		}
	}
}

四、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;
			}
		}

	}
	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) {
		new MainClass();
	}
}

五、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;
	}
}

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