hibernate创建实体类的类型详解

系统管理员 2022-07-24 06:08 213阅读 0赞

首先上两个实体类：

package entity;
    
    import javax.persistence.Basic;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.Id;
    import java.util.Date;
    
    /**
     * Created by raid on 2016/5/14.
     */
    @Entity
    public class Students {
        private Integer sid;
        private String sname;
        private String gender;
        private Date birthday;
        private String address;
        private Address ad;
    
        public Students() {
        }
    
        public Students(Integer sid, String sname, String gender, Date birthday, String address) {
            this.sid = sid;
            this.sname = sname;
            this.gender = gender;
            this.birthday = birthday;
            this.address = address;
        }
    
        public Students(String sname, String gender, Date birthday, String address) {
            this.sname = sname;
            this.gender = gender;
            this.birthday = birthday;
            this.address = address;
        }
    
        @Id
        @Column(name = "sid")
        public Integer getSid() {
            return sid;
        }
    
        public void setSid(Integer sid) {
            this.sid = sid;
        }
    
        @Basic
        @Column(name = "sname")
        public String getSname() {
            return sname;
        }
    
        public void setSname(String sname) {
            this.sname = sname;
        }
    
        @Basic
        @Column(name = "gender")
        public String getGender() {
            return gender;
        }
    
        public void setGender(String gender) {
            this.gender = gender;
        }
    
        @Basic
        @Column(name = "birthday")
        public Date getBirthday() {
            return birthday;
        }
    
        public void setBirthday(Date birthday) {
            this.birthday = birthday;
        }
    
        @Basic
        @Column(name = "address")
        public String getAddress() {
            return address;
        }
    
        public void setAddress(String address) {
            this.address = address;
        }
        @Basic
        @Column(name = "ad")
        public Address getAd() {
            return ad;
        }
    
        public void setAd(Address ad) {
            this.ad = ad;
        }
    
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
    
            Students students = (Students) o;
    
            if (sid != null ? !sid.equals(students.sid) : students.sid != null) return false;
            if (sname != null ? !sname.equals(students.sname) : students.sname != null) return false;
            if (gender != null ? !gender.equals(students.gender) : students.gender != null) return false;
            if (birthday != null ? !birthday.equals(students.birthday) : students.birthday != null) return false;
            if (address != null ? !address.equals(students.address) : students.address != null) return false;
    
            return true;
        }
    
        @Override
        public int hashCode() {
            int result = sid != null ? sid.hashCode() : 0;
            result = 31 * result + (sname != null ? sname.hashCode() : 0);
            result = 31 * result + (gender != null ? gender.hashCode() : 0);
            result = 31 * result + (birthday != null ? birthday.hashCode() : 0);
            result = 31 * result + (address != null ? address.hashCode() : 0);
            return result;
        }
    }

package entity;
    
    /**
     * Created by raid on 2016/5/15.
     */
    public class Address {
    
        private String postcode;
        private String phone;
        private String ad;
    
        public Address() {
        }
    
        public Address(String postcode, String phone, String ad) {
            this.postcode = postcode;
            this.phone = phone;
            this.ad = ad;
        }
    
        public String getPostcode() {
            return postcode;
        }
    
        public void setPostcode(String postcode) {
            this.postcode = postcode;
        }
    
        public String getPhone() {
            return phone;
        }
    
        public void setPhone(String phone) {
            this.phone = phone;
        }
    
        public String getAd() {
            return ad;
        }
    
        public void setAd(String ad) {
            this.ad = ad;
        }
    }

上面两个类，其实就一个实体Students，Address是包含在Students中的属性，所以对于的Students.hbm.xml文件应该这样配置：

<?xml version='1.0' encoding='utf-8'?>
    <!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
    
        <class name="entity.Students" table="students" schema="hibernate">
            <id name="sid" column="sid">
                <generator class="native"/>
            </id>
            <property name="sname" column="sname"/>
            <property name="gender" column="gender"/>
            <property name="birthday" column="birthday"/>
            <property name="address" column="address"/>
            <component name="ad" class="entity.Address">
                <property name="postcode" column="postcode"/>
                <property name="phone" column="phone"/>
                <property name="ad" column="ad"/>
            </component>
        </class>
    </hibernate-mapping>

其中，主键为自增长类型，所以需要配置：

如果数据库存储的类型是datetime类型，那么实体类就要设置成java.util.Date这个类

如果属性是另外一个类的话，那么就需要使用component标签来实现。

在配置文件中，name是实体类的数据域名称，column是对应的数据库的属性名称。