根据这本书,当我更新ElementCOllection List时,我不执行Transection.begin,休眠将自动提交,但是我对其进行了测试,结果有问题
我的Main.java是
public class Main {
private static UserService userService;
private static Logger logger = LoggerFactory.getLogger(Main.class);
public static void main(String[] args) {
ApplicationContext applicationContext =
new AnnotationConfigApplicationContext(RootConfig.class);
userService = applicationContext.getBean(UserService.class);
User user = new User("qwerty");
user.getMessages().add("hello,world");
userService.save(user);
User user1 = userService.findByName("qwerty");
user1.getMessages().add("ncjdksckds");
System.out.println(user);
}
}
我的配置在这里,按照书中的编码
@Configuration
@ComponentScan(basePackages = {"org.zhy"})
@EnableJpaRepositories(basePackages = {"org.zhy.repository"})
@EnableTransactionManagement
public class RootConfig {
@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter ) {
LocalContainerEntityManagerFactoryBean emfb =
new LocalContainerEntityManagerFactoryBean();
emfb.setDataSource(dataSource);
emfb.setJpaVendorAdapter(jpaVendorAdapter);
emfb.setPersistenceUnitName("demo");
Properties hibernateProperties = new Properties();
hibernateProperties.setProperty("hibernate.hbm2ddl.auto", "create-drop");
emfb.setJpaProperties(hibernateProperties);
emfb.setPackagesToScan("org.zhy.domain");
return emfb;
}
@Bean
public PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
JpaTransactionManager transactionManager = new JpaTransactionManager();
transactionManager.setEntityManagerFactory(entityManagerFactory);
return transactionManager;
}
@Bean
public DataSource dataSource() {
DriverManagerDataSource ds = new DriverManagerDataSource();
ds.setDriverClassName("com.mysql.jdbc.Driver");
// some setting here such as url...
return ds;
}
@Bean
public JpaVendorAdapter jpaVendorAdapter() {
HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
adapter.setGenerateDdl(false);
adapter.setDatabase(Database.MYSQL);
adapter.setShowSql(true);
adapter.setDatabasePlatform("org.hibernate.dialect.MySQLDialect");
return adapter;
}
}
实体在这里
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
@ElementCollection(fetch = FetchType.EAGER)
private List<String> messages = new ArrayList<String>();
//getter and setter
当我使用
user1.getMessages().add("ncjdksckds");
数据库没有自动将新消息刷新到其中,我想知道为什么? 最佳答案
不确定您要指的是哪本书,但有关@ElementCollection的关键是默认情况下所有操作都是级联的。
假设您的服务具有所有标记为事务性的公共方法,则在查询用户之后,它是一个分离的实体。从现在开始,它在任何事务范围之外。
在您的代码中:
User user = new User("qwerty");
user.getMessages().add("hello,world");
userService.save(user); // new transaction start and finish
User user1 = userService.findByName("qwerty"); // new transaction start and finish
user1.getMessages().add("ncjdksckds"); // this change is outside of a transaction
为了使更改持久化,您需要将
merge
实体user1
回到持久化上下文中:userService.merge(user1);
在内部您会打电话给:
entityManager.merge(user);