下面是我如何重构你的代码。我最终得到了四个接口和四个类。您需要为其中两个接口添加实现。
首先对数据进行封装-User：

package report;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class User {

    private final String name;

    private final String email;
    private final List<Double> scores;

    public User(String name, String email, List<Double> scores) {
        if ((name == null) || (name.trim().length() == 0)) throw new IllegalArgumentException("Name cannot be blank or null");
        if ((email == null) || (email.trim().length() == 0)) throw new IllegalArgumentException("Email cannot be blank or null");
        this.name = name.trim();
        this.email = email.trim();
        this.scores = (scores != null) ? new ArrayList<>(scores) : new ArrayList<>();
    }

    public String getName() {
        return name;
    }

    public String getEmail() {
        return email;
    }

    public List<Double> getScores() {
        return Collections.unmodifiableList(scores);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        User user = (User) o;

        if (!getName().equals(user.getName())) return false;
        if (!getEmail().equals(user.getEmail())) return false;
        return getScores().equals(user.getScores());
    }

    @Override
    public int hashCode() {
        int result = getName().hashCode();
        result = 31 * result + getEmail().hashCode();
        result = 31 * result + getScores().hashCode();
        return result;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", scores=" + scores +
                '}';
    }
}

我使用运行在JDK 17下的IntelliJ 2023.1创建了User类。这可能是使用记录类的一个很好的例子。
创建一个接口UserRepository和一个实现，它只与关系数据库交互：

package report;

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

public interface UserRepository {

    User findByName(String name);

    default void close(ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
            }
        } catch (SQLException e) {
            // log at best
        }
    }
    default void close(Statement st) {
        try {
            if (st != null) {
                st.close();
            }
        } catch (SQLException e) {
            // log at best.
        }
    }

    default void close(Connection connection) {
        try {
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            // log at best.
        }
    }
}

下面是一个实现：

package report;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserRepositoryImpl implements UserRepository {

    public static final String FIND_BY_NAME = "SELECT NAME, EMAIL, SCORE1, SCORE2, SCORE3, SCORE4 FROM SCORE_TABLE WHERE NAME = ?";

    private final Connection connection;

    public UserRepositoryImpl(Connection connection) {
        this.connection = connection;
    }

    @Override
    public User findByName(String name) {
        User user;
        ResultSet rs = null;
        PreparedStatement ps = null;
        try {
            ps = this.connection.prepareStatement(FIND_BY_NAME);
            rs = ps.executeQuery();
            user = new UserMapper().mapRow(rs);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            close(rs);
            close(ps);
        }
        return user;
    }
}

存储库实现使用RowMapper接口和UserMapper实现：

package report;

import java.sql.ResultSet;

public interface RowMapper<T> {
    T mapRow(ResultSet rs);
}

下面是UserMapper的实现：

package report;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class UserMapper implements RowMapper<User> {

    @Override
    public User mapRow(ResultSet rs) {
        User user = null;
        try {
            while (rs.next()) {
                String name = rs.getString("NAME");
                String email = rs.getString("EMAIL");
                List<Double> scores = new ArrayList<>();
                scores.add(rs.getDouble("SCORE1"));
                scores.add(rs.getDouble("SCORE2"));
                scores.add(rs.getDouble("SCORE3"));
                scores.add(rs.getDouble("SCORE4"));
                user = new User(name, email, scores);
            }
        } catch (SQLException e) {
            user = null;
        }
        return user;
    }
}

碧玉报告生成器和电子邮件客户端有以下接口：

package report;

public interface JasperReportGenerator<T> {

    byte [] generate(String jrxml, T data);
}

package report;

public interface EmailClient {

    void send(String from, String to, String subject, String body, byte [] attachment);
}

这是比你的单一方法更多的类。这种方法有几个优点：

• 每个班做好一件事（单一责任原则）
• 使用Junit单独测试每个类很容易。

看看这个方法是否对你有帮助。