嗨，我如何用一笔交易来操作其他dao

Question

我有一个dao，哪些方法应该在一个事务中。正确执行该操作的最佳方法是什么？车道有以下方法

public Car findCar(int numOfPas,String carCategory){
String query = "SELECT*FROM car_info WHERE numOfPas = ? AND carCategory=? AND carState='ready' ORDER BY RAND() LIMIT 1;";
Car foundCar = null;
ResultSet resultSet = null;
try (Connection connection = MySQLDAOFactory.getConnection();
PreparedStatement statement = connection.prepareStatement(query)){
statement.setInt(1,numOfPas);
statement.setString(2,carCategory);
resultSet =statement.executeQuery();
if(resultSet.next()){
foundCar = new Car();
foundCar.setCarId(resultSet.getInt("carId"));
foundCar.setCarCategory(resultSet.getString("carCategory"));
foundCar.setNumOfPas(resultSet.getInt("numOfPas"));
foundCar.setCarState(resultSet.getString("carState"));
foundCar.setCarName(resultSet.getString("carName"));
foundCar.setCarImage(manager.byteToImage(resultSet.getBytes("carImage")));
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
if(resultSet!=null){
try {
resultSet.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
return foundCar;
}

订单刀有以下

@Override
public boolean insertOrder(Order order) {
int rowNum = 0;
String query = "INSERT INTO user_order(userId,carId,userAddress,userDestination,orderCost,orderDate) values(?,?,?,?,?,?)";
ResultSet keys = null;
try (Connection connection = MySQLDAOFactory.getConnection();
PreparedStatement statement = connection.prepareStatement(query,Statement.RETURN_GENERATED_KEYS)){
statement.setInt(1,order.getUserId());
statement.setInt(2,order.getCarId());
statement.setString(3, order.getUserAddress());
statement.setString(4, order.getUserDestination());
statement.setDouble(5,order.getOrderCost());
statement.setTimestamp(6, Timestamp.valueOf(order.getOrderDate()));
rowNum = statement.executeUpdate();
keys = statement.getGeneratedKeys();
if(keys.next()){
order.setOrderId(keys.getInt(1));
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}
return rowNum>0;
}

如何将这些操作放在一个事务中？我通过Apache dhcp连接池接收连接。

编辑的

这是类我在哪里接电话公共类MySQLDAOFactory扩展了DAOFactory{

public static Connection getConnection(){
Connection conn = null;
try {
Context initContext = new InitialContext();
Context envContext = (Context) initContext.lookup("java:comp/env");
DataSource ds = (DataSource) envContext.lookup("jdbc/UsersDB");
conn = ds.getConnection();
} catch (NamingException | SQLException e) {
e.printStackTrace();
}
return conn;
}
@Override
public CarDao getCarDao() {
return new MySQLCarDao();
}
@Override
public UserDao getUserDao() {
return new MySQLUserDao();
}
@Override
public OrderDao getOrderDao() {
return new MySQLOrderDao();
}
@Override
public CarCategoryDao getCarCategoryDao() {
return new MySQLCarCategoryDao();
}
}

Answer 1

管理事务有很多不同的方法。给定您的代码，最简单的方法是：

在try块中：

1. 在包装两个调用的调用者中创建connection
2. 执行connection.setAutoCommit(false)
3. 调用每个方法findCar()和insertOrder()
4. 致电connection.commit();

在catch块中：

呼叫connection.rollback()

connection不是在这些函数之外创建的，所以不要忘记从每个函数中删除连接设置。