Spring + JPA「超出鎖定等待超時;嘗試重新啓動事務」

Question

我是Spring和JPA的新手，遇到標題中指定的問題。爲了簡化問題，我有兩個類：User和FeedItem。用戶可以有更多的FeedItem，但關係是雙向的（FeedItem知道它與哪個用戶關聯）。他們都堅持在數據庫中使用JPA + Hibernate的：

@Entity 
@Table 
public class User 
{ 
    @Id 
    @GeneratedValue 
    @Column(name = "id", nullable = false, length = 8) 
    private int id; 

    @Column(nullable = false, length = 32, unique = true) 
    private String alias; 

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "user") 
    private List<FeedItem> feedItems = new ArrayList<FeedItem>(); 

    public User() 
    { 
    } 

    public User(String alias) 
    { 
     this.alias = alias; 
    } 

    ... getters/setters... 
} 


@Entity 
@Table 
public class FeedItem 
{ 
    @Id 
    @GeneratedValue 
    @Column(name = "id", nullable = false, length = 16) 
    private int id; 

    @Column(nullable = false, length = 64) 
    private String title; 

    @ManyToOne 
    @JoinColumn(name = "userId", nullable = false) 
    private User user; 

    public FeedItem() 
    { 
    } 

    public FeedItem(String title, User user) 
    { 
     this.title = title; 
     this.user = user; 
    } 

    ... getters/setters... 
} 

的DAO中：

@Repository 
public class UserJpaDao implements UserDao 
{ 
    private EntityManager em; 

    @Transactional 
    public User save(User user) 
    { 
     return this.em.merge(user); 
    } 

    @Transactional 
    public void delete(User user) 
    { 
     this.em.remove(user); 
    } 

    @Transactional(readOnly = true) 
    public User findById(int id) 
    { 
     return this.em.find(User.class, id); 
    } 

    @PersistenceContext 
    void setEntityManager(EntityManager entityManager) 
    { 
     this.em = entityManager; 
    } 
} 


@Repository 
public class FeedItemJpaDao implements FeedItemDao 
{ 
    private EntityManager em; 

    @Transactional 
    public FeedItem save(FeedItem feedItem) 
    { 
     return this.em.merge(feedItem); 
    } 

    @Transactional 
    public void delete(FeedItem feedItem) 
    { 
     this.em.remove(feedItem); 
    } 

    @Transactional 
    public FeedItem findById(int id) 
    { 
     return this.em.find(FeedItem.class, id); 
    } 

    @PersistenceContext 
    void setEntityManager(EntityManager entityManager) 
    { 
     this.em = entityManager; 
    } 
} 

這是測試給出錯誤：

@RunWith(SpringJUnit4ClassRunner.class) 
public class FeedItemJpaDaoTest 
{ 
    @Autowired 
    private DriverManagerDataSource dataSource; 

    @Autowired 
    private FeedItemJpaDao feedItemDao; 

    @Autowired 
    private UserJpaDao userDao; 

    @Before 
    @Transactional 
    public void setUp() throws Exception 
    { 
     DatabaseOperation.CLEAN_INSERT.execute(getConnection(), getDataSet()); 
    } 

    @After 
    @Transactional 
    public void tearDown() throws Exception 
    { 
     DatabaseOperation.DELETE_ALL.execute(getConnection(), getDataSet()); 
    } 

    @Test 
    @Transactional 
    public void testSave() throws Exception 
    { 
     User user = userDao.findById(3); 
     FeedItem feedItem = new FeedItem("Achievement unlocked!", user); 
     feedItem = feedItemDao.save(feedItem); 
     assertEquals(feedItem, feedItemDao.findById(feedItem.getId())); 
    } 

    private IDatabaseConnection getConnection() throws Exception 
    { 
     return new DatabaseConnection(dataSource.getConnection()); 
    } 

    private IDataSet getDataSet() throws Exception 
    { 
     return new FlatXmlDataSetBuilder().build(new File("src/test/resources/dataset.xml")); 
    } 
} 

我不明白爲什麼錯誤發生 - 任何建議表示讚賞！

謝謝。

編輯：好像這個問題是由於DbUnit的：如果我註釋掉的刪除（）方法，誤差不occour

Answer 1

解決了以下這個問題：http://tadaya.wordpress.com/2008/04/27/transaction-aware-datasource-use-dbunit-hibernate-in-spring/