JPA一对多映射表示例.pdf

JPA ⼀对多映射表⽰例 JPA教程 - JPA⼀对多映射表⽰例 以下代码显⽰如何使⽤连接表来链接⼀对多映射。 它使⽤ @JoinTable 注释来设置连接表。 @OneToMany @JoinTable(name = PERSON_DEPT, joinColumns = @JoinColumn(name = p ivate SetPe son pe sons = new HashSetPe son(); 例⼦ 下⾯的代码来⾃Department .j ava 。 package mon; impo t java.util.HashSet; impo t java.util.Set; impo t javax .pe sistence.CascadeType; impo t javax .pe sistence.Entity; impo t javax .pe sistence.Gene atedValue; impo t javax .pe sistence.Gene ationType; impo t javax .pe sistence.Id; impo t javax .pe sistence.JoinColumn; impo t javax .pe sistence.JoinTable; impo t javax .pe sistence.OneToMany; @Entity public class Depa tment { @Id @Gene atedValue(st ategy=Gene ationType.IDENTITY) p ivate long id; p ivate St ing name; @OneToMany @JoinTable(name = PERSON_DEPT, joinColumns = @JoinColumn(name p ivate SetPe son pe sons = new HashSetPe son(); public SetPe son getPe sons() { etu n pe sons; } public void setPe sons(SetPe son pe sons) { this.pe sons = pe sons; } public long getId() { etu n id; } public void setId(long id) { this.id = id; } public St ing getName() { etu n name; } public void setName(St ing name) { = name; } @Ove ide public St ing toSt ing() { etu n Depa tment [id= + id + , name= + name + , pe sons= + ]; } } 下⾯的代码来⾃Person .j ava 。 package mon; impo t javax .pe sistence.Entity; impo t javax .pe sistence.Gene atedValue; impo t javax .pe sistence.Gene ationType; impo t javax .pe sistence.Id; impo t javax .pe sistence.ManyToOne; impo t javax .pe sistence.CascadeType; @Entity public class Pe son { @Id @Gene atedValue(st ategy=Gene ationType.IDENTITY) p ivate long id; p ivate St ing name; @ManyToOne (cascade=CascadeType.ALL) p ivate Depa tment depa tment; public Pe son() {} public Pe son(St ing name) { = name; } public Depa tment getDepa tme