Question

我有两个hibernate类TestAuthor和TestBook，如下面的代码所示。我在表格中插入了一些记录，并成功插入。为确保记录正确插入，我使用了以下内容 SQL命令

SELECT * from TESTAUTHOR;
SELECT * from afk_owner.TestBook;

我现在想要使用下面的PrintAll部分中显示的Hibernate命令显示表testbook的内容。当我运行方法PrintAll时，我收到一个异常读取：

cannot be cast to msc.hibernate.persistence.TestBook

为什么我会发现这个错误以及如何解决它。？

PrintAll ：

private void printAll() {

    for (TestBook book : (List<TestBook>) HibernateUtil.getCurrentSession().createSQLQuery("SELECT * from afk_owner.testbook").list()) {

        System.out.println(book.getmISBN() + ", " + book.getmTitle() + " " + (book.getAuthor()));
    }
}

TestAuthor ：

@Entity @Table(schema = "afk_owner", name = "testauthor")
public class TestAuthor {

@Id
@Column(name = "authorid")
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sequencegen")
@SequenceGenerator(name = "sequencegen", sequenceName = "afk_owner.testauthor_seq", allocationSize = 1)
private Integer mAuthorID;

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

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

@OneToMany(mappedBy = "author")
private List<TestBook> books;

public Integer getmAuthorID() {
    return mAuthorID;
}

public void setmAuthorID(Integer mAuthorID) {
    this.mAuthorID = mAuthorID;
}

public String getmFName() {
    return mFName;
}

public void setmFName(String mFName) {
    this.mFName = mFName;
}

public String getmLName() {
    return mLName;
}

public void setmLName(String mLName) {
    this.mLName = mLName;
}

public TestAuthor() {
    // TODO Auto-generated constructor stub
}
}

TestBook ：

@Entity @Table(schema = "afk_owner", name = "testbook")
public class TestBook {

@Id
@Column(name = "ISBN")
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sequencegen")
@SequenceGenerator(name = "sequencegen", sequenceName = "afk_owner.testbook_seq", allocationSize = 1)
private Long mISBN;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "authorid")
private TestAuthor author;

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

public Long getmISBN() {
    return mISBN;
}

public void setmISBN(Long mISBN) {
    this.mISBN = mISBN;
}

public TestAuthor getAuthor() {
    return author;
}

public void setAuthor(TestAuthor author) {
    this.author = author;
}


public String getmTitle() {
    return mTitle;
}

public void setmTitle(String mTitle) {
    this.mTitle = mTitle;
}

public TestBook() {
    // TODO Auto-generated constructor stub
}
}

Answer 1

使用Hibernate API和本机SQL是不可能的。没有类型控制，所以你必须强制转换。根据{{3}}有可能，但在Session Api docs中可以省略它。您必须弄清楚如何使用它来满足您的需求。由于这些解决方案被标记为已弃用，因此您应该完全避免使用它。您应该尝试转移到JPA并使用Hibernate作为其实现。

如果你想使用HQL，它可以工作。查询将是这样的：

Query<TestBook> query=session.createQuery("SELECT tb FROM TestBook tb WHERE tb.author.mAuthorID=:owner",TestBook.class); query.setParameter("author",authorId); List<TestBook> books=query.list();

您只需调整属性名称（tb，作者，id属性）等以满足您的需求，但您可以了解如何使用它。

如何将列表转换为表名

1 个答案: