使用 JPA/Hibernate，如何将 Java 枚举映射到 MySQL 表中的列？答案

【问题标题】：Using JPA/Hibernate, how do I map a Java enum to a column in my MySQL table?使用 JPA/Hibernate，如何将 Java 枚举映射到 MySQL 表中的列？
【发布时间】：2014-02-21 22:07:39
【问题描述】：

我正在使用 Hibernate 4.3.0.Final (JPA 2.1) 和 MySQL 5.5。我想将我的 Java 枚举映射到具有相应值的 MySQL 表。所以我的枚举是

public enum Roles
{
    STUDENT("Student"),
    TEACHER("Teacher"),
    …

    Roles(final String name)
    {
        this.name = name;
    }

    private final String name;

    @Override
    public String toString()
    {
        return getName();
    }

    public String getName()
    {
        return this.name;
    }
}

我的表包含类似的值

+------------------------+------------------------+-------------+
| ID                     | NAME                   | ADMIN_LEVEL |
+------------------------+------------------------+-------------+
| Student                | Student                |           1 |
| Teacher                | Teacher                |          10 |

那么，在代表上表的一个实体类中，我有

@GenericGenerator(name = "uuid-strategy", strategy = "org.mainco.subco.core.util.subcoUUIDGenerator")
@Entity(name = "sb_role")
public class Role implements Serializable, Comparable<Role>
{

    @Id
    @NotNull
    @GeneratedValue(generator = "uuid-strategy")
    @Column(name = "ID")
    /* the database id of the role */
    private String id;

    @Enumerated(value=EnumType.STRING)
    @Column(name = "NAME")
    /* the String name of the role */
    private Roles name;

但是，当我运行我的应用程序时，我遇到了如下错误。如何强制枚举值和数据库中的列之间的完整性？

java.lang.IllegalArgumentException: Parameter value [Student] did not match expected type [org.mainco.subco.user.domain.Roles (n/a)]
    at org.hibernate.jpa.spi.BaseQueryImpl.validateBinding(BaseQueryImpl.java:885)
    at org.hibernate.jpa.internal.QueryImpl.access$000(QueryImpl.java:80)
    at org.hibernate.jpa.internal.QueryImpl$ParameterRegistrationImpl.bindValue(QueryImpl.java:248)
    at org.hibernate.jpa.spi.BaseQueryImpl.setParameter(BaseQueryImpl.java:631)
    at org.hibernate.jpa.spi.AbstractQueryImpl.setParameter(AbstractQueryImpl.java:179)
    at org.hibernate.jpa.spi.AbstractQueryImpl.setParameter(AbstractQueryImpl.java:49)
    at org.hibernate.jpa.criteria.compile.CriteriaCompiler$1$1.bind(CriteriaCompiler.java:126)
    at org.hibernate.jpa.criteria.CriteriaQueryImpl$1.buildCompiledQuery(CriteriaQueryImpl.java:386)
    at org.hibernate.jpa.criteria.compile.CriteriaCompiler.compile(CriteriaCompiler.java:147)
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:736)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:241)
    at com.sun.proxy.$Proxy71.createQuery(Unknown Source)
    at org.mainco.subco.core.repo.AbstractHibernateDAO.findByUniqueConstraint(AbstractHibernateDAO.java:104)
    at org.mainco.subco.user.repo.RoleDaoImpl.findRoleByName(RoleDaoImpl.java:26)
    at org.mainco.subco.user.service.RoleServiceImpl.findByName(RoleServiceImpl.java:43)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at com.sun.proxy.$Proxy91.findByName(Unknown Source)
    at org.mainco.subco.resource.service.ResourceServiceIT.testFindById(ResourceServiceIT.java:95)

我对编写 @Converter 不感兴趣（要考虑的值太多了），除非那是绝对最简单的解决方案。

【问题讨论】：

标签： mysql hibernate jpa enums jpa-2.0

【解决方案1】：

@Enumerated(value=EnumType.STRING)

使用 ENUM 的值学生老师

不是你在括号中的那个，在你的数据库中你有以小写开头的值在数据库中进行更新以使该列中的所有值都大写，这是最简单的解决方案，它应该可以工作，并且不会影响数据完整性。 XD。

【讨论】：