JPA 1.0中是否有任何JPA流利的API/Critera API？我正在使用OpenJPA

Question

是否有任何jpa 1.0流利的api /接口用於查詢構建？我使用的是openjpa 1.x，所以我被JPA1困住了。

我發現QueryByProxy，但其maven回購工作不正常。

Answer 1

如果您遇到JPA 1.0，請考慮使用Querydsl，它在JPA之上提供流暢的類型安全API。您必須使用1.6.0之前的版本，即1.5.4（他們在1.6.0中轉換爲JPA 2.0）。這是IMO最好的選擇。

Answer 2

簡短的回答是沒有。但是，這取決於您使用的提供商。例如，如果您使用的是Hibernate，那麼您總是可以從休眠狀態獲取Criteria API。但是在JPA 1.0中不支持。但是在JPA 2.0中。

Answer 3

您可以在JPA和Hibernate中使用Fluent接口模式。我寫了an article which explains this topic in great detail。

要總結一下，如果你正在使用Hibernate，你可以修改制定者返回實體：

@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; 
    } 
} 

這種方式，你可以建立家長和孩子的實體是這樣的：

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); 
}); 

如果你關心JPA的便攜性，那麼你可能不想違反Java Bean的規範，在這種情況下，你需要添加流利的接口方法一起定期制定者：

@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; 
    } 
} 

實體建築幾乎等同於前一個：

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); 
});