java - 如何在关闭 Java 连接之前返回 ResultSet

Question

我只想编写 1 个执行方法并在需要时重新使用它，而无需重写整个方法。下面是我返回 ResultSet 的方法。

public ResultSet executeSelect() {
    Connection con = null;
    PreparedStatement prepared = null;
    ResultSet rs = null;
    try {
        con = C_DB.getConnection();
        prepared = con.prepareStatement(this.getQuery());

        if(!this.midQuery.equals("")) {
            int i = 1;
            for (String val: this.values) {
                prepared.setString(i, val);
                i++;
            }
        }

        rs =  prepared.executeQuery();
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        try {
            if (prepared != null) {
                prepared.close();
            }
            if (con != null) {
                con.close();
            }
        } catch(SQLException e) {
            e.printStackTrace();
        }
    }
    return rs;
}

问题是在 executeSelect() 执行后，Connection、PreparedStatement 和 ResultSet 在返回数据之前关闭，所以我得到了这个错误 java.sql.SQLException: Operation not allowed after ResultSet closed

我想要返回 ResultSet 的原因是我可以为任何对象数据重新使用 executeData 方法。例如:

C_Query q = new C_Query(dataSearch,"SELECT * FROM people ", " ORDER BY id DESC");
ResultSet rs = q.executeSelect()

ObservableList<C_Person> peopleData = FXCollections.observableArrayList();
while(rs.next()){
    C_Person person = new C_Person();
    person.setFirstName(rs.getString("firstName"));
    person.setLastName(rs.getString("lastName"));
    peopleData.add(person);
}

和

C_Query q = new C_Query(dataSearch,"SELECT * FROM cars", " ORDER BY id DESC");
ResultSet rs = q.executeSelect()

ObservableList<C_Car> CarData = FXCollections.observableArrayList();
while(rs.next()){
    C_Car car = new C_Car();
    car.type(rs.getString("type"));
    car.brand(rs.getString("brand"));
    CarData.add(car);
}

我该如何解决这个问题？

Answer 1

“CachedRowSet”正是为此而生的: https://docs.oracle.com/javase/6/docs/api/javax/sql/rowset/CachedRowSet.html