Java实现数据库连接

要实现Java与数据库的连接，需要使用Java数据库连接（JDBC）API。以下是Java代码示例，演示如何连接MySQL数据库：

1. 导入JDBC驱动程序

Class.forName("com.mysql.jdbc.Driver");

2. 建立数据库连接

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");

其中，localhost:3306是MySQL服务器的地址和端口号，mydatabase是要连接的数据库名称，username和password是MySQL登录凭据。

3. 执行SQL查询

Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM customers");
while (rs.next()) {
    String name = rs.getString("name");
    String email = rs.getString("email");
    System.out.println("Name: " + name + ", Email: " + email);
}

以上代码执行查询并遍历结果集，输出每个客户的姓名和电子邮件地址。

4. 关闭数据库连接

rs.close();
stmt.close();
conn.close();

在应用程序结束时，必须关闭数据库连接以释放资源。完整代码如下所示：

import java.sql.*;

public class MySQLExample {
    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");

            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM customers");
            while (rs.next()) {
                String name = rs.getString("name");
                String email = rs.getString("email");
                System.out.println("Name: " + name + ", Email: " + email);
            }

            rs.close();
            stmt.close();
            conn.close();
        } catch (Exception e) {
            System.out.println("Error: " + e.getMessage());
        }
    }
}