java连接数据库做简单图书管理系统

好的，下面是一个简单的Java连接数据库并实现图书管理系统的示例代码：

1. 首先需要在MySQL数据库中创建一个名为"library"的数据库，并在其中创建一个名为"books"的表，包括以下字段：id、title、author、publisher、price。

2. 在Java中引入MySQL的JDBC驱动包，以便连接数据库。可以在pom.xml文件中添加以下依赖：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.19</version>
</dependency>

3. 在Java代码中连接数据库，可以使用以下代码：

import java.sql.*;

public class DatabaseConnection {
    private Connection conn;
    
    public DatabaseConnection() {
        String driver = "com.mysql.cj.jdbc.Driver";
        String url = "jdbc:mysql://localhost:3306/library?useSSL=false&serverTimezone=UTC";
        String username = "root";
        String password = "password";
        try {
            Class.forName(driver);
            conn = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    public Connection getConnection() {
        return conn;
    }
    
    public void closeConnection() {
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

4. 在Java中实现图书管理系统的功能，可以使用以下代码：

import java.sql.*;

public class LibraryManagement {
    private DatabaseConnection dbConn;
    
    public LibraryManagement() {
        dbConn = new DatabaseConnection();
    }
    
    public void addBook(Book book) {
        Connection conn = dbConn.getConnection();
        String sql = "INSERT INTO books(title, author, publisher, price) VALUES (?, ?, ?, ?)";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, book.getTitle());
            pstmt.setString(2, book.getAuthor());
            pstmt.setString(3, book.getPublisher());
            pstmt.setDouble(4, book.getPrice());
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    public void updateBook(Book book) {
        Connection conn = dbConn.getConnection();
        String sql = "UPDATE books SET title=?, author=?, publisher=?, price=? WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, book.getTitle());
            pstmt.setString(2, book.getAuthor());
            pstmt.setString(3, book.getPublisher());
            pstmt.setDouble(4, book.getPrice());
            pstmt.setInt(5, book.getId());
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    public void deleteBook(int id) {
        Connection conn = dbConn.getConnection();
        String sql = "DELETE FROM books WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    public Book findBookById(int id) {
        Connection conn = dbConn.getConnection();
        String sql = "SELECT * FROM books WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                Book book = new Book();
                book.setId(rs.getInt("id"));
                book.setTitle(rs.getString("title"));
                book.setAuthor(rs.getString("author"));
                book.setPublisher(rs.getString("publisher"));
                book.setPrice(rs.getDouble("price"));
                rs.close();
                pstmt.close();
                return book;
            }
            rs.close();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    public List<Book> findAllBooks() {
        Connection conn = dbConn.getConnection();
        String sql = "SELECT * FROM books";
        List<Book> books = new ArrayList<>();
        try {
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery(sql);
            while (rs.next()) {
                Book book = new Book();
                book.setId(rs.getInt("id"));
                book.setTitle(rs.getString("title"));
                book.setAuthor(rs.getString("author"));
                book.setPublisher(rs.getString("publisher"));
                book.setPrice(rs.getDouble("price"));
                books.add(book);
            }
            rs.close();
            stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return books;
    }
    
    public void close() {
        dbConn.closeConnection();
    }
}

其中Book类的代码如下：

public class Book {
    private int id;
    private String title;
    private String author;
    private String publisher;
    private double price;
    
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getTitle() {
        return title;
    }
    
    public void setTitle(String title) {
        this.title = title;
    }
    
    public String getAuthor() {
        return author;
    }
    
    public void setAuthor(String author) {
        this.author = author;
    }
    
    public String getPublisher() {
        return publisher;
    }
    
    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }
    
    public double getPrice() {
        return price;
    }
    
    public void setPrice(double price) {
        this.price = price;
    }
}

使用示例：

LibraryManagement lm = new LibraryManagement();
lm.addBook(new Book("Java编程思想", "Bruce Eckel", "机械工业出版社", 89.00));
lm.addBook(new Book("Java核心技术", "Cay S. Horstmann", "机械工业出版社", 99.00));
lm.updateBook(new Book(1, "Java编程思想（第4版）", "Bruce Eckel", "机械工业出版社", 99.00));
lm.deleteBook(2);
Book book = lm.findBookById(1);
System.out.println(book.getTitle());
List<Book> books = lm.findAllBooks();
for (Book b : books) {
    System.out.println(b.getTitle());
}
lm.close();