请使用JDBC的方式完成下述要求： 1\在 "students" 表中插入一条记录，包含学生的姓名为 "Alice"，年龄为 18，班级为 "A1"。 2\从 "students" 表中删除所有年龄小于 15 的学生记录。 3\更新 "students" 表中学生姓名为 "Bob" 的记录，将其年龄改为 20。 4\查询 "students" 表中所有年龄大于等于 18 的学生记录。 5\查询 "students" 表中所有班级为 "B2" 的学生记录。 6\从 "students" 表中删除姓名为 "

以下是使用 JDBC 完成要求的示例代码：

import java.sql.*;

public class JDBCExample {
    private static final String JDBC_URL = "jdbc:mysql://localhost:3306/test?user=root&password=root";

    public static void main(String[] args) {
        try {
            Connection conn = DriverManager.getConnection(JDBC_URL);

            // 插入一条记录
            String insertSql = "INSERT INTO students (name, age, class) VALUES (?, ?, ?)";
            PreparedStatement insertStmt = conn.prepareStatement(insertSql);
            insertStmt.setString(1, "Alice");
            insertStmt.setInt(2, 18);
            insertStmt.setString(3, "A1");
            insertStmt.executeUpdate();
            System.out.println("插入记录成功");

            // 删除年龄小于 15 的学生记录
            String deleteSql = "DELETE FROM students WHERE age < ?";
            PreparedStatement deleteStmt = conn.prepareStatement(deleteSql);
            deleteStmt.setInt(1, 15);
            int deleteCount = deleteStmt.executeUpdate();
            System.out.println("删除了 " + deleteCount + " 条记录");

            // 更新学生姓名为 "Bob" 的记录
            String updateSql = "UPDATE students SET age = ? WHERE name = ?";
            PreparedStatement updateStmt = conn.prepareStatement(updateSql);
            updateStmt.setInt(1, 20);
            updateStmt.setString(2, "Bob");
            int updateCount = updateStmt.executeUpdate();
            System.out.println("更新了 " + updateCount + " 条记录");

            // 查询年龄大于等于 18 的学生记录
            String querySql1 = "SELECT name, age, class FROM students WHERE age >= ?";
            PreparedStatement queryStmt1 = conn.prepareStatement(querySql1);
            queryStmt1.setInt(1, 18);
            ResultSet rs1 = queryStmt1.executeQuery();
            while (rs1.next()) {
                String name = rs1.getString("name");
                int age = rs1.getInt("age");
                String clazz = rs1.getString("class");
                System.out.println(name + ", " + age + ", " + clazz);
            }

            // 查询班级为 "B2" 的学生记录
            String querySql2 = "SELECT name, age, class FROM students WHERE class = ?";
            PreparedStatement queryStmt2 = conn.prepareStatement(querySql2);
            queryStmt2.setString(1, "B2");
            ResultSet rs2 = queryStmt2.executeQuery();
            while (rs2.next()) {
                String name = rs2.getString("name");
                int age = rs2.getInt("age");
                String clazz = rs2.getString("class");
                System.out.println(name + ", " + age + ", " + clazz);
            }

            // 删除姓名为 "Tom" 的学生记录
            String deleteSql2 = "DELETE FROM students WHERE name = ?";
            PreparedStatement deleteStmt2 = conn.prepareStatement(deleteSql2);
            deleteStmt2.setString(1, "Tom");
            int deleteCount2 = deleteStmt2.executeUpdate();
            System.out.println("删除了 " + deleteCount2 + " 条记录");

            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

注意：上述代码中的表名、字段名、JDBC URL 等需要根据实际情况修改。同时还需要导入 MySQL JDBC 驱动。