srping-data-jpa 实体配置_jpa 实体 longtext配置-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_44327322/article/details/108273637

本文详细解析了Spring Data JPA中实体类的配置方式，包括自增ID、字段类型映射、一对一、多对一、多对多关联及复合主键的实现方法。

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srping-data-jpa 实体配置

自增ID

@Id
@GeneratedValue
@Column(name = "ID" , nullable = false)
private long id = 0;

String字段对应数据库varchar类型

@Column(name = "CName" , nullable = false , length = 50)
private String name = "";

boolean字段对应数据库bit类型

@Column(name = "OptionalMayFlag", nullable = false, columnDefinition = "bit")
private boolean optionalMayFlag = false;

大文本对应数据库longtext

@Lob
@Column(name = "Answer", nullable = false)
private String answer = null;

一对一

@OneToOne(cascade = CascadeType.ALL, optional = false)
@PrimaryKeyJoinColumn(name = "SchoolID", referencedColumnName = "ID")
private School school;

多对一

@ManyToOne(cascade = CascadeType.REFRESH, optional = true)
@JoinColumn(name = "StageID" , nullable = false)
private Stage stage;

多对多

@ManyToMany(cascade = CascadeType.REFRESH, fetch = FetchType.LAZY)
	@JoinTable(name = "t_user_subject", joinColumns = { @JoinColumn(name = "UserID", referencedColumnName = "ID") }, inverseJoinColumns = { @JoinColumn(name = "SubjectID", referencedColumnName = "ID") })
	@OrderBy(value = "order")
	private List<Subject> subjects = new ArrayList<Subject>();

复合主键

@Entity
@Table(name = "hw_question")
public class Question implements Serializable {
	@Id
	@GeneratedValue
	@Column(name = "ID", nullable = false)
	private long id = 0;
}

@IdClass(value=QuestionContentKey.class)
@Entity
@Table(name = "hw_questioncontent")
public class QuestionContent implements Serializable {
	@Id
	private Question question;
	@Id
	private int questionIndex = 0;
}

///

public class QuestionContentKey implements Serializable{
	@ManyToOne(cascade = CascadeType.REFRESH, optional = false)
	@JoinColumn(name = "QuestionID", nullable = false)
	private Question question;
	@Column(name = "QuestionIndex", nullable = false)
	private Integer questionIndex = 0;
}