编译查询时出错：抽象模式类型“实体”未知

Question

我正在开发一个带有数据库连接的游戏，我使用 JPA 来保存我的数据。这是我的游戏实体：

 @Entity
@Table(name = "game")
public class Game implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "game_id")
private int id;

@Column(name = "name")
private String name;

@Column(name = "nbTurns")
private int nbTurns;

@Column(name = "playedOn")
@Temporal(TemporalType.TIMESTAMP)
private Date playedOn;

@ElementCollection(fetch = FetchType.EAGER)
@CollectionTable(name = "game_humans", joinColumns = @JoinColumn(name = "game_id"))
@MapKeyColumn(name = "human_id")
@Column(name = "isDead")
private Map<Human, Boolean> humans;

这是我的人类实体：

 @Entity
@Table(name = "human")
public class Human implements Serializable {

private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
@Column(name = "name")
private String name;
@OneToOne
private Building building;

为了获取存储在数据库中的所有人员的列表，我使用了这个 DAO，它运行良好并且还获取了 Building 实体：

 public class HumanDAO implements DAO<Human> {

// ...
public List<Human> getAllHumans() {
    TypedQuery<Human> query = em.createQuery("SELECT h FROM human h ORDER BY h.name", Human.class);
    return query.getResultList();
}

问题是当我尝试使用 JPQL 查询 SELECT g FROM game g 获取所有游戏的列表时，我收到此错误：

 [EL Info]: 2013-11-25 13:40:27.761--ServerSession(1943119327)--EclipseLink, version: Eclipse Persistence Services - 2.5.0.v20130507-3faac2b
[EL Info]: connection: 2013-11-25 13:40:28.151--ServerSession(1943119327)--file:/Users/amine/Documents/workspace/ZombiesServer/target/classes/_ZombiesServer login successful
[WARNING]
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:297)
    at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager:
Exception Description: Problem compiling [SELECT g FROM game g].
[14, 18] The abstract schema type 'game' is unknown.
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1585)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1605)
    at com.amine.zombies.DAO.GameDAO.getAllGames(GameDAO.java:80)
    at com.amine.zombies.application.Application.main(Application.java:21)
    ... 6 more

原文由 Mohamed Amine 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

你应该有

SELECT g FROM Game g//you have game

但是你有 game 而不是 Game 。

@Table 注释用于数据库。

如果您需要更改 JPQL 中的名称，请使用 @Entity 注释： @Entity(name="nameUsedInJPQL") => nameUsedInJPQL is used in your JPQL.

如果您未在 @Entity 中指定任何内容，则使用区分大小写的实体类名称。

原文由 V G 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 2

就我而言，我忘记在 persistence.xml 中注册它。

原文由 leomeurer 发布，翻译遵循 CC BY-SA 3.0 许可协议