Hibernate持久化ArrayList-问题
问题内容:
遇到一些麻烦。我正在创建一个带有锦标赛的网站,用户可以注册。比赛将列出注册会员。它不保存用户对象,而只保存用户电子邮件地址,这始终是用户表的关键。我想以这样的方式存储数组列表:我将拥有多个比赛ID的副本,但每个比赛ID仅一个用户名实例。
例如T_ID用户名1 Tom 1 Mike 1 John 2 Tom 2 Chris 2 Timmy 3 Timmy 3 Chris
等等
这是表的SQL。
DROP TABLE IF EXISTS `mtc`.`tournament` ;
CREATE TABLE IF NOT EXISTS `mtc`.`tournament` (
`id` INT NOT NULL,
`tournamentName` VARCHAR(100) NULL,
`tournamentGender` VARCHAR(45) NULL,
`tournamentType` VARCHAR(45) NULL,
`tournamentCategory` VARCHAR(45) NULL,
`tournamentStyle` VARCHAR(45) NULL,
PRIMARY KEY (`id`))
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mtc`.`tournament_eligible`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `mtc`.`tournament_eligible` ;
CREATE TABLE IF NOT EXISTS `mtc`.`tournament_eligible` (
`id` INT NOT NULL,
`username` VARCHAR(45) NULL,
PRIMARY KEY (`id`),
CONSTRAINT `fk_tournament_eligible_tournament1`
FOREIGN KEY (`id`)
REFERENCES `mtc`.`tournament` (`id`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
我有两节课。
Tournament.java
@Entity
@Table(name = "tournament")
public class Tournament implements Event {
@Id
@GeneratedValue
private int id;
@OneToMany
@JoinColumn(name = "id")
private List<User> eligible; // Contains a list of eligible members
@Size(min = 5, max = 45, message = "Tournament Name must be between 5 and 60 characters", groups = {
PersistenceValidationGroup.class, FormValidationGroup.class })
private String tournamentName; // Specified the name of the tournament
private String tournamentGender = "MIXED"; // Specifies where a tournament
// is M(ale), F(emale) or MIXED;
private String tournamentType = "S"; // Specifies S(ingles) or D(oubles)
private String tournamentCategory = "O"; // Specifies Member_Type to be
// S(enior) only, J(unior) only,
// or O(pen) Tournament
private String tournamentStyle = "L"; // Specfies type of Tournament to be
// (L)adder/(L)eague, (B)ucket or
// (G)roup - Probably change this to
// a class later on.
public Tournament() {
this.eligible = new ArrayList<User>();
}
// getters and setters
寄存器类
@Entity
@Table(name="tournament_eligible")
public class Registered {
@Id
@Column(name="id")
private int tournamentID;
@Column(name="username")
private String username;
@OneToMany(mappedBy="tournament")
private List<String> registered;
// getter and setters
我使用的是正确的javax。*注释,而不是Hibernate的注释。
当前错误:由以下原因引起:org.hibernate.AnnotationException:events.tournaments.Tournament.eligible上的@OneToOne或@ManyToOne引用了一个未知实体:java.util.List
我确实设置了Hibernate配置,以使用Register实体在程序包中查找。
<beans profile="production">
<jee:jndi-lookup jndi-name="jdbc/mtc" id="dataSource"
expected-type="javax.sql.DataSource">
</jee:jndi-lookup>
<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"></property>
</bean>
<tx:annotation-driven />
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
<property name="dataSource" ref="dataSource"></property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
</props>
</property>
<property name="packagesToScan">
<list>
<value>users</value>
<value>dao</value>
<value>events.tournaments</value>
</list>
</property>
</bean>
<bean id="exceptionTranslator"
class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor">
</bean>
</beans>
问题答案:
在您的Register
课程中,您尝试映射一个字符串列表,就好像它们是实体一样:
@OneToMany(mappedBy="tournament")
private List<String> registered;
@OneToMany
仅用于实体之间的关系。无论是List
也不String
是实体。如果要将Collection
基本值(如String
)映射到表,请查看@CollectionTable
批注。