JPA 1.0是否有任何JPA Fluent API/Critera API?我用的是OpenJPA

如果你坚持使用JPA1.0,那么考虑使用 Querydsl 它在JPA之上提供了一个流畅的类型安全API。您必须使用1.6.0之前的版本,即1.5.4(它们在1.6.0中切换到JPA2.0)。这是我的最佳选择。

简短的回答是“否”。但这取决于您使用的提供程序。例如,如果您使用的是Hibernate,那么您总是可以从Hibernate中获取标准API。然而,在JPA1.0中,这是不受支持的。但在JPA2.0中是这样的。

您可以将Fluent接口模式与JPA和Hibernate一起使用。我写 an article which explains this topic in great detail .

总而言之,如果您使用的是Hibernate,您只需修改setter返回实体:

@Entity(name = "Post")
@Table(name = "post")
public class Post {

    @Id
    private Long id;

    private String title;

    public Post() {}

    public Post(String title) {
        this.title = title;
    }

    @OneToMany(
        cascade = CascadeType.ALL, 
        orphanRemoval = true, 
        mappedBy = "post"
    )
    private List<PostComment> comments = new ArrayList<>();

    public Long getId() {
        return id;
    }

    public Post setId(Long id) {
        this.id = id;
        return this;
    }

    public String getTitle() {
        return title;
    }

    public Post setTitle(String title) {
        this.title = title;
        return this;
    }

    public List<PostComment> getComments() {
        return comments;
    }

    public Post addComment(PostComment comment) {
        comment.setPost(this);
        comments.add(comment);
        return this;
    }
}

@Entity(name = "PostComment")
@Table(name = "post_comment")
public class PostComment {

    @Id
    @GeneratedValue
    private Long id;

    private String review;

    private Date createdOn;

    @ManyToOne
    private Post post;

    public Long getId() {
        return id;
    }

    public PostComment setId(Long id) {
        this.id = id;
        return this;
    }

    public String getReview() {
        return review;
    }

    public PostComment setReview(String review) {
        this.review = review;
        return this;
    }

    public Date getCreatedOn() {
        return createdOn;
    }

    public PostComment setCreatedOn(Date createdOn) {
        this.createdOn = createdOn;
        return this;
    }

    public Post getPost() {
        return post;
    }

    public PostComment setPost(Post post) {
        this.post = post;
        return this;
    }
}

这样,您可以这样构建父实体和子实体:

doInJPA(entityManager -> {
    Post post = new Post()
    .setId(1L)
    .setTitle("High-Performance Java Persistence")
    .addComment(
        new PostComment()
        .setReview("Awesome book")
        .setCreatedOn(Timestamp.from(
            LocalDateTime.now().minusDays(1).toInstant(ZoneOffset.UTC))
        )
    )
    .addComment(
        new PostComment()
        .setReview("High-Performance Rocks!")
        .setCreatedOn(Timestamp.from(
            LocalDateTime.now().minusDays(2).toInstant(ZoneOffset.UTC))
        )
    )
    .addComment(
        new PostComment()
        .setReview("Database essentials to the rescue!")
        .setCreatedOn(Timestamp.from(
            LocalDateTime.now().minusDays(3).toInstant(ZoneOffset.UTC))
        )
    );
    entityManager.persist(post);
});

如果您关心JPA可移植性,那么您可能不希望违反JavaBean规范,在这种情况下,您需要沿着正则设置器添加FLUENT接口方法:

@Entity(name = "Post")
@Table(name = "post")
public class Post {

    @Id
    private Long id;

    private String title;

    public Post() {}

    public Post(String title) {
        this.title = title;
    }

    @OneToMany(
        cascade = CascadeType.ALL, 
        orphanRemoval = true, 
        mappedBy = "post"
    )
    private List<PostComment> comments = new ArrayList<>();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Post id(Long id) {
        this.id = id;
        return this;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public Post title(String title) {
        this.title = title;
        return this;
    }

    public List<PostComment> getComments() {
        return comments;
    }

    public Post addComment(PostComment comment) {
        comments.add(comment.post(this));
        return this;
    }
}

@Entity(name = "PostComment")
@Table(name = "post_comment")
public class PostComment {

    @Id
    @GeneratedValue
    private Long id;

    private String review;

    private Date createdOn;

    @ManyToOne
    private Post post;

    public Long getId() {
        return id;
    }

    public PostComment setId(Long id) {
        this.id = id;
        return this;
    }

    public String getReview() {
        return review;
    }

    public void setReview(String review) {
        this.review = review;
    }

    public PostComment review(String review) {
        this.review = review;
        return this;
    }

    public Date getCreatedOn() {
        return createdOn;
    }

    public void setCreatedOn(Date createdOn) {
        this.createdOn = createdOn;
    }

    public PostComment createdOn(Date createdOn) {
        this.createdOn = createdOn;
        return this;
    }

    public Post getPost() {
        return post;
    }

    public void setPost(Post post) {
        this.post = post;
    }

    public PostComment post(Post post) {
        this.post = post;
        return this;
    }
}

实体建筑几乎与前一个相同:

doInJPA(entityManager -> {
    Post post = new Post()
    .id(1L)
    .title("High-Performance Java Persistence")
    .addComment(new PostComment()
        .review("Awesome book")
        .createdOn(Timestamp.from(
            LocalDateTime.now().minusDays(1).toInstant(ZoneOffset.UTC))
        )
    )
    .addComment(new PostComment()
        .review("High-Performance Rocks!")
        .createdOn(Timestamp.from(
            LocalDateTime.now().minusDays(2).toInstant(ZoneOffset.UTC))
        )
    )
    .addComment(new PostComment()
        .review("Database essentials to the rescue!")
        .createdOn(Timestamp.from(
            LocalDateTime.now().minusDays(3).toInstant(ZoneOffset.UTC))
        )
    );
    entityManager.persist(post);
});