spring boot hibernate常用注解

深碍√TFBOYSˉ_ 2022-04-14 03:21 249阅读 0赞

### **hibernate常用注解** ###

# 表注 #

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>  创建表

//不声明entity表无法创建
    @Entity
    @Table(name = "表名")
    @DynamicInsert
    @DynamicUpdate
    //解决hibernate json 延时加载，接受参数，字段无效问题
    @JsonIgnoreProperties(value={"hibernateLazyInitializer","handler","fieldHandler"})

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>  主键

**   uuid Oracle使用**

@Id
    @GeneratedValue(generator = "uuid2")
    @GenericGenerator(name = "uuid2", strategy = "uuid2")

**自增 mysql使用**

@Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "列名",unique = true,nullable = false)

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> **不会生成数据库列**

@Transient

--------------------

> **查询默认排序**

@OrderBy(value = "列名 ASC")

> **枚举类型（数据库存储序列，或字符）**

@Enumerated(EnumType.ORDINAL)//序列自动不需要配置
    @Enumerated(EnumType.STRING)//例如Sex.MAN 存储MAN

> **自定义数据类型**

@Column(name = "列名",columnDefinition ="数据库类型")

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###  **实体类关系** ###

> **一对一关系**

**单向关系 **

@OneToOne(cascade ={CascadeType.DETACH,CascadeType.PERSIST,CascadeType.MERGE},fetch = FetchType.LAZY)
    
    @JoinColumn(name="外键列名")

**双向关系**

@OnegToOne(mappedBy = "参考映射对象",cascade = {CascadeType.DETACH,
    
    CascadeType.PERSIST, CascadeType.MERGE}, fetch = FetchType.LAZY)

--------------------

> **多对一关系**

**ManyToOne****（多对一）单向：不产生中间表**

@ManyToOne(cascade = {CascadeType.DETACH, CascadeType.PERSIST, CascadeType.MERGE},
    fetch = FetchType.LAZY)
    @JoinColumn(name = "外键列名")

**OneToMany（一对多）单向：会产生中间表**

**OneToMany****双向使用mappedy属性不会产生中间表**

@OneToMany(cascade = {CascadeType.DETACH, CascadeType.PERSIST, CascadeType.MERGE}
    ,fetch = FetchType.LAZY)
    @JoinTable(name = "中间表名", joinColumns = @JoinColumn(name = "当前类id"),
    
            inverseJoinColumns = @JoinColumn(name = "集合类型id"))

--------------------

> **多对多关系**

**多对多由一方维护关系即可**

**双向关系**

@ManyToMany(mappedBy = "映射集合",cascade =
     {CascadeType.DETACH,CascadeType.PERSIST, CascadeType.MERGE}
    , fetch = FetchType.LAZY)

**映射为另一方的关系**

--------------------

> ** 懒加载死循环**

@JsonIgnoreProperties不同于@JsonIgnore在于，你可以注明该变量中的哪个属相不被序列化。从而允许在双向访问上都不存在环或是缺失。

@JsonIgnoreProperties("另一方对象或集合名称")

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### 级联操作 ###