【hibernate】之关于一对多单向关联映射

基于外键的一对多关联映射！

一对多，Group(组)对于Person(人)，一个组能够有多个人!ok?

Hibernate主要有两种配置方法。一种是Annotations 一种是XML！

以下是Annotations的配置方法！

@Entity@Table(name="t_group")publicclass Group {    private Integer id;    private String name;    private Set
       
         persons=newHashSet
        
         ();//set不同意反复，最适合数据库模型    @Id    @GeneratedValue    public Integer getId() {       returnid;    }    publicvoid setId(Integerid) {       this.id = id;    }    @Column(name="t_name")    public String getName() {       returnname;    }    publicvoid setName(Stringname) {       this.name = name;    }    @OneToMany     //加上@JoinColumn是为了防止Hibernate将一对多当做多对多来处理,产生中间表    @JoinColumn(name="group_id")    public Set
         
          getPersons() {       returnpersons;    }    publicvoidsetPersons(Set
          
            persons){       this.persons = persons;    }}
          
         
        
       

@Entity@Table(name="t_person")publicclass Person {    private Integer id;    private String name;    private Integer age;    @Id    @GeneratedValue    public Integer getId() {       returnid;    }    publicvoid setId(Integerid) {       this.id = id;    }    @Column(name="t_name")    public String getName() {       returnname;    }    publicvoid setName(Stringname) {       this.name = name;    }    @Column(name="t_age")    public Integer getAge() {       returnage;    }    publicvoid setAge(Integerage) {       this.age = age;    }}

XML配置一对多的单向关联映射

publicclass Person {    private Integer id;    private String name;    private Integer age;    public Integer getId() {       returnid;    }    publicvoid setId(Integerid) {       this.id = id;    }    public String getName() {       returnname;    }    publicvoid setName(Stringname) {       this.name = name;    }    public Integer getAge() {       returnage;    }    publicvoid setAge(Integerage) {       this.age = age;    }}

publicclass Group {    private Integer id;    private String name;    private Set
       
         persons=newHashSet
        
         ();//set不同意反复，最适合数据库模型    public Integer getId() {       returnid;    }    publicvoid setId(Integerid) {       this.id = id;    }    public String getName() {       returnname;    }    publicvoid setName(Stringname) {       this.name = name;    }    public Set
         
          getPersons() {       returnpersons;    }    publicvoidsetPersons(Set
          
            persons) {       this.persons = persons;    }}
          
         
        
       

xml version="1.0"?

> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="csg.hibernate.entity"> <class name="Group"table="t_group"> <id name="id"> <column name="id"/> <generator class="native" /> </id> <property name="name" /> <set name="persons"> <key column="group_id"/> <one-to-many class="csg.hibernate.entity.Person"/> </set> </class> </hibernate-mapping>

xml version="1.0"?

> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="csg.hibernate.entity"> <class name="Person"table="t_person"> <id name="id"> <column name="id"/> <generator class="native" /> </id> <property name="name" /> <property name="age" /> </class> </hibernate-mapping>

Ok，一对多单向关联映射的Annotations和XML配置方法！