hibernate 注解方式实现联合主键 博客分类: Hibernate hibernate注解联合主键
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2024-03-19 10:29:52
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联合主键的实现方式有三种
方式1.将联合主键的字段单独放在一个类中,该类需要实现java.io.Serializable接口并重写equals和hascode,再将该类注解为@Embeddable,最后在主类中(该类不包含联合主键类中的字段)保存该联合主键类的一个引用,并生成set和get方法,并将该引用注解为@Id
@Embeddable public class DogPrimarykey implements Serializable { private static final long serialVersionUID = 2555027553374060423L; private String id; @Column(name="DOG_NAME") private String name; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((id == null) ? 0 : id.hashCode()); result = prime * result + ((name == null) ? 0 : name.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; DogPrimarykey other = (DogPrimarykey) obj; if (id == null) { if (other.id != null) return false; } else if (!id.equals(other.id)) return false; if (name == null) { if (other.name != null) return false; } else if (!name.equals(other.name)) return false; return true; } }
@Entity(name = "DOG") public class Dog { private static final long serialVersionUID = 7219216851705947642L; @Id private DogPrimarykey dogPrimarykey; @Column(name = "DOG_AGE", length = 2) private int age; public DogPrimarykey getDogPrimarykey() { return dogPrimarykey; } public void setDogPrimarykey(DogPrimarykey dogPrimarykey) { this.dogPrimarykey = dogPrimarykey; } public int getAge() { return age; } public void setAge(int age) { if (age > 100 || age < 1) { this.age = 1; } else { this.age = age; } } public void say() { // TODO Auto-generated method stub System.out.println("汪 汪 汪"); } @Override public String toString() { return "Dog [dogPrimarykey=" + dogPrimarykey + ", age=" + age + "]"; } }
方式2:将联合主键的字段单独放在一个类中,该类需要实现java.io.Serializable接口并重写equals和hascode,最后在主类中(该类不包含联合主键类中的字段)保存该联合主键类的一个引用,并生成set和get方法,并将该引用注解为@EmbeddedId
public class DogPrimarykey implements Serializable { private static final long serialVersionUID = 2555027553374060423L; private String id; @Column(name="DOG_NAME") private String name; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((id == null) ? 0 : id.hashCode()); result = prime * result + ((name == null) ? 0 : name.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; DogPrimarykey other = (DogPrimarykey) obj; if (id == null) { if (other.id != null) return false; } else if (!id.equals(other.id)) return false; if (name == null) { if (other.name != null) return false; } else if (!name.equals(other.name)) return false; return true; } }
@Entity(name = "DOG") public class Dog { private static final long serialVersionUID = 7219216851705947642L; @EmbeddedId private DogPrimarykey dogPrimarykey; @Column(name = "DOG_AGE", length = 2) private int age; public DogPrimarykey getDogPrimarykey() { return dogPrimarykey; } public void setDogPrimarykey(DogPrimarykey dogPrimarykey) { this.dogPrimarykey = dogPrimarykey; } public int getAge() { return age; } public void setAge(int age) { if (age > 100 || age < 1) { this.age = 1; } else { this.age = age; } } public void say() { // TODO Auto-generated method stub System.out.println("汪 汪 汪"); } @Override public String toString() { return "Dog [dogPrimarykey=" + dogPrimarykey + ", age=" + age + "]"; } }
方式3:将联合主键的字段单独放在一个类中,该类需要实现java.io.Serializable接口并要重写equals和hashcode.最后在主类中(该类包含联合主键类中的字段)将联合主键字段都注解为@Id,并在该类上方加上这样的注解:@IdClass(联合主键类.class)
public class DogPrimarykey implements Serializable { private static final long serialVersionUID = 2555027553374060423L; private String id; @Column(name="DOG_NAME") private String name; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((id == null) ? 0 : id.hashCode()); result = prime * result + ((name == null) ? 0 : name.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; DogPrimarykey other = (DogPrimarykey) obj; if (id == null) { if (other.id != null) return false; } else if (!id.equals(other.id)) return false; if (name == null) { if (other.name != null) return false; } else if (!name.equals(other.name)) return false; return true; } }
@Entity(name = "DOG") @IdClass(DogPrimarykey.class) public class Dog { private static final long serialVersionUID = 7219216851705947642L; @Id private String id; @Id private String name; @Column(name = "DOG_AGE", length = 2) private int age; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { if (age > 100 || age < 1) { this.age = 1; } else { this.age = age; } } public void say() { // TODO Auto-generated method stub System.out.println("汪 汪 汪"); } @Override public String toString() { return "Dog [id=" + id + ", name=" + name + ", age=" + age + "]"; } }