Question

这是我的实体类

 @EmbeddedId

private AuthorWorkPKEmbedded embeddedId;

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

public AuthorWorkPKEmbedded getEmbeddedId() {
    return embeddedId;
}

public void setEmbeddedId(AuthorWorkPKEmbedded embeddedId) {
    this.embeddedId = embeddedId;
}

public String getColumnA() {
    return ColumnA;
}

public void setColumnA(String ColumnA) {
    this.ColumnA = ColumnA;
}



public AuthorWorkEmbedded() {
}

public AuthorWorkEmbedded(BigInteger bookId,BigInteger authorId) {
    this.embeddedId = new AuthorWorkPKEmbedded(bookId, authorId);
}

这是我的Embeddable类

 @Embeddable
@Column(name = "bookId", nullable = false)
private BigInteger bookId;

@Column(name = "authorId", nullable = false)
private BigInteger authorId;

public AuthorWorkPKEmbedded() {
}

public AuthorWorkPKEmbedded(BigInteger bookId, BigInteger authorId) {
    this.bookId = bookId;
    this.authorId = authorId;
}

public BigInteger getBookId() {
    return bookId;
}

public void setBookId(BigInteger bookId) {
    this.bookId = bookId;
}

public BigInteger getAuthorId() {
    return authorId;
}

public void setAuthorId(BigInteger authorId) {
    this.authorId = authorId;
}

@Override
public int hashCode() {
    return bookId.hashCode() + authorId.hashCode();
}

@Override
public boolean equals(Object obj) {
    if (obj == this) {
        return true;
    }
    if (!(obj instanceof AuthorWorkPKEmbedded)) {
        return false;
    }
    if (obj == null) {
        return false;
    }
   AuthorWorkEmbedded pk=(AuthorWorkEmbedded) obj;
   return (((bookId==((AuthorWorkPKEmbedded)obj).getBookId()))
           &&((authorId==((AuthorWorkPKEmbedded)obj).getAuthorId())));
}

这是我的主要课程如何设置复合值以及为什么我们不能将generatedvalue用于自动增量目的以及如何从数据库中检索值以及在Entity类或embeddable类中声明其他字段的另一个方法，如果不是如何设置和获取值这两个类（实体和嵌入式）

 EntityTransaction entr = em.getTransaction();
        entr.begin();
        AuthorWorkPKEmbedded author = new AuthorWorkPKEmbedded();
        author.setBookId(BigInteger.ONE);
        author.setAuthorId(BigInteger.ONE);

        AuthorWorkEmbedded a1=new AuthorWorkEmbedded();
        a1.setEmbeddedId(author);
        a1.setColumnA("Pirates of carrabian");

        boolean successful = false;
        try {
            em.persist(author);
            successful = true;
        } finally {
            if (successful) {
                entr.commit();
            } else {
                entr.rollback();
            }
        }
        Query query = em.createNamedQuery("AuthorWork.findAll");
        List authorList = query.getResultList();
        Iterator authorIterator = authorList.iterator();
        while (authorIterator.hasNext()) {
            author = (AuthorWorkPKEmbedded) authorIterator.next();
            System.out.println("Book Id " + author.getBookId() + " " + "Author" + author.getAuthorId() + "");
            System.out.println();
        }

Answer 1

使用embeddedId的getter和setter。

Query query = em.createNamedQuery("AuthorWork.findAll");
        List authorList = query.getResultList();
        Iterator authorIterator = authorList.iterator();
        while (authorIterator.hasNext()) {
            author = (AuthorWorkEmbedded) authorIterator.next();
            System.out.println("Book Id " + author.setEmbeddedId().getBookId() + " " + "Author" + author.getEmbeddedId().getAuthorId() + "");
            System.out.println(""+author.getColumnA());
        }

如何在jpa中设置和获取Composite主键和其他字段的值？

1 个答案: