java - JPA 1.0 是否有任何 JPA fluent API / Critera api？我正在使用 OpenJPA

Question

是否有任何 jpa 1.0 fluent api/interface 用于查询构建？我正在使用openjpa 1.x，所以我坚持使用JPA1。

我找到了 QueryByProxy，但它的 maven repo 工作不正常。

Answer 1

如果您坚持使用 JPA 1.0，那么请考虑使用在JPA 之上提供流式类型安全 API 的Querydsl。您必须使用 1.6.0 之前的版本，即 1.5.4（他们在 1.6.0 中切换到 JPA 2.0）。这是 IMO 您最好的选择。

Answer 2

简短的回答是否定的。但是，这取决于您使用的提供商。例如，如果您使用的是 Hibernate，则始终可以从 hibernate 获取 Criteria api。但是在 JPA 1.0 中不支持此功能。但是在 JPA 2.0 中是这样。

Answer 3

您可以使用Fluent Interface PatternJPA 和 Hibernate。

总结一下，如果您使用的是 Hibernate，您只需修改设置器以返回实体：

@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，您可以像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 的可移植性，那么您可能不想违反 Java Bean 规范，在这种情况下，您需要添加 Fluent Interface 方法以及常规 setter：

@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;
    }
}

实体构建与上一个几乎相同：

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);
});