Hibernate屬性級別註解

一、關鍵字
@Id:主鍵屬性 定義多個主鍵屬性 ，必須實現serializable
@SequenceGenerator
@GeneratedValue
@Column
@Embedded
@EmbeddedId
@Lob
@Version
@Basic
@Transient：表示該屬性並非一個到數據庫表的字段映射,ORM 框架將忽略該屬性，ORM 默認爲@Basic

二、關係映射級別註解
1.一對一單向外鍵關聯
2.一對一雙向外鍵關聯
3.一對一單向外鍵聯合主鍵
4.多對一單向外鍵關聯
5.一對多單向外鍵關聯
6.一對多雙向外鍵關聯
7.多對多單向外鍵關聯
8.多對多雙向外鍵關聯
三.實體間的映射關係
1.一對一：一個公民對應一個身份證號
2.一對多（多對一）：一個公民可以有多個賬號
3.多對多：一個學生可以有多個老師，一個老師可以有多個學生
1.一對一單向外鍵關聯
創建IdCard表(身份證)

@Entity
public class IdCard {
    private String cardNumber;
    private String sname;
    @Id
    @GeneratedValue(generator = "cardNumber")
    @GenericGenerator(name="cardNumber",strategy = "assigned")
    @Column(length=18)
    public String getCardNumber() {
        return cardNumber;
    }

    public void setCardNumber(String cardNumber) {
        this.cardNumber = cardNumber;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public IdCard() {
    }

    public IdCard(String cardNumber, String sname) {
        this.cardNumber = cardNumber;
        this.sname = sname;
    }
}

創建Students類（學生）

@Entity
public class Students {
    private String sid ;
    private String gender;
    private Date birthday;
    private String major;
    private IdCard idCard;
    public Students(){

    }

    public Students(String gender, String sid, Date birthday, String major,IdCard idCard) {
        this.gender = gender;
        this.sid = sid;
        this.birthday = birthday;
        this.major = major;
        this.idCard = idCard;
    }
    @Id
    @GeneratedValue(generator = "sid")
    @GenericGenerator(name="sid",strategy = "assigned")
    @Column(length=8)
    public String getSid() {
        return sid;
    }

    public void setSid(String sid) {
        this.sid = sid;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }
    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "cardNumber")
    public IdCard getIdCard() {
        return idCard;
    }

    public void setIdCard(IdCard idCard) {
        this.idCard = idCard;
    }
}

2.一對一雙向外鍵關聯

package ec.efeiyi.com;

import org.hibernate.annotations.GenericGenerator;

import javax.persistence.*;

/**
 * Created by Administrator on 2016/6/23.
 */
@Entity
public class IdCard {
    private String cardNumber;
    private String sname;
    private Students students;
    @Id
    @GeneratedValue(generator = "cardNumber")
    @GenericGenerator(name="cardNumber",strategy = "assigned")
    @Column(length=18)
    public String getCardNumber() {
        return cardNumber;
    }

    public void setCardNumber(String cardNumber) {
        this.cardNumber = cardNumber;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }
    @OneToOne(mappedBy = "idCard")
    public Students getStudents() {
        return students;
    }

    public void setStudents(Students students) {
        this.students = students;
    }

    public IdCard() {
    }

    public IdCard(String cardNumber, String sname) {
        this.cardNumber = cardNumber;
        this.sname = sname;
    }
}

一對多單向外鍵關聯
例如一個ClassRoom可以有多個學生
ClassRoom類

@Entity
public class ClassRoom {
    private String cid;//班級編號
    private String cname;//班級名字
    private List<Students> stu;//一方持有多方集合
    public ClassRoom(){

    }

    public ClassRoom(String cid, String cname) {
        this.cid = cid;
        this.cname = cname;
    }
    @Id
    @GeneratedValue(generator = "cid")
    @GenericGenerator(name="cid",strategy = "assigned")
    public String getCid() {
        return cid;
    }

    public void setCid(String cid) {
        this.cid = cid;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }
    @OneToMany(cascade = {CascadeType.ALL},fetch = FetchType.LAZY)
    @JoinColumn(name="cid")
    public List<Students> getStu() {
        return stu;
    }
    public void setStu(List<Students> stu) {
        this.stu = stu;
    }
}

Students類

@Entity
public class Students {
    private String sid ;
    private String gender;
    private Date birthday;
    private String major;
    public Students(){

    }

    public Students(String gender, String sid, Date birthday, String major) {
        this.gender = gender;
        this.sid = sid;
        this.birthday = birthday;
        this.major = major;
    }
    @Id
    @GeneratedValue(generator = "sid")
    @GenericGenerator(name="sid",strategy = "assigned")
    @Column(length=8)
    public String getSid() {
        return sid;
    }

    public void setSid(String sid) {
        this.sid = sid;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }
}

生成表結構students

生成表結構classroom

多對多單向外鍵關聯
教師和學生構成多對多的關聯關聯關係
其中一個多方持有另一個多方集合(學生持有教師集合)
類別和商品多對多的關係（小電器和剃鬚刀）
爲甚麼需要中間表

Students類

@Entity
public class Students {
    private String sid ;
    private String gender;
    private Date birthday;
    private String major;
    private List<Teachers> teacherList;
    public Students(){

    }

    public Students(String gender, String sid, Date birthday, String major) {
        this.gender = gender;
        this.sid = sid;
        this.birthday = birthday;
        this.major = major;
    }
    @Id
    @GeneratedValue(generator = "sid")
    @GenericGenerator(name="sid",strategy = "assigned")
    @Column(length=8)
    public String getSid() {
        return sid;
    }

    public void setSid(String sid) {
        this.sid = sid;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }
    @ManyToMany
    @JoinTable(name="teachers_students",joinColumns = {@JoinColumn(name="sid")},inverseJoinColumns = {@JoinColumn(name="tid")})
    public List<Teachers> getTeacherList() {
        return teacherList;
    }

    public void setTeacherList(List<Teachers> teacherList) {
        this.teacherList = teacherList;
    }
}

Techers類

@Entity
public class Teachers {
    private String tid;
    private String name;
    @Id
    @GeneratedValue(generator = "tid")
    @GenericGenerator(name="tid",strategy = "assigned")
    public String getTid() {
        return tid;
    }
    public void setTid(String tid) {
        this.tid = tid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

生成數據庫students

生成數據庫表teachers

生成數據庫表

save操作案例

   Session session = getSession();
         Transaction tran = session.beginTransaction();
        try {
            Students s1 = new Students();
            s1.setSid("10000001");
            s1.setMajor("cs");
            s1.setGender("male");
            s1.setBirthday(new Date());
            ArrayList<Teachers> list = new ArrayList<>();
            Teachers t1 = new Teachers();
            t1.setTid("t0001");
            t1.setName("Mr.Wang");
            Teachers t2 = new Teachers();
            t2.setTid("t0002");
            t2.setName("Mr.Chow");
            list.add(t1);
            list.add(t2);
            s1.setTeacherList(list);
            session.save(t1);
            session.save(t2);
            session.save(s1);
            tran.commit();
        } finally {
            session.close();
        }

雙向多對多的映射
Techers類

@Entity
public class Teachers {
    private String tid;
    private String name;
    private List<Students> studentList;
    @Id
    @GeneratedValue(generator = "tid")
    @GenericGenerator(name="tid",strategy = "assigned")
    public String getTid() {
        return tid;
    }
    public void setTid(String tid) {
        this.tid = tid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    @ManyToMany(mappedBy = "teacherList")
    public List<Students> getStudentList() {
        return studentList;
    }

    public void setStudentList(List<Students> studentList) {
        this.studentList = studentList;
    }
}

Students類

@Entity
public class Students {
    private String sid ;
    private String gender;
    private Date birthday;
    private String major;
    private List<Teachers> teacherList;
    public Students(){

    }

    public Students(String gender, String sid, Date birthday, String major) {
        this.gender = gender;
        this.sid = sid;
        this.birthday = birthday;
        this.major = major;
    }
    @Id
    @GeneratedValue(generator = "sid")
    @GenericGenerator(name="sid",strategy = "assigned")
    @Column(length=8)
    public String getSid() {
        return sid;
    }

    public void setSid(String sid) {
        this.sid = sid;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }
    @ManyToMany
    @JoinTable(name="teachers_students",joinColumns = {@JoinColumn(name="sid")},inverseJoinColumns = {@JoinColumn(name="tid")})
    public List<Teachers> getTeacherList() {
        return teacherList;
    }

    public void setTeacherList(List<Teachers> teacherList) {
        this.teacherList = teacherList;
    }
}