Hibernate的多种关系映射（oto、otm、mtm）
前提：使用注解映射
一、一对一（夫妻关系表）
两个表：hus1和wife1表，外键为id，各自有名字hname和wname
映射得到两个类：Hus1和Wife1类
Hus1类（主表）：
package com.weikun.po; import javax.persistence.*; /** * Created by Administrator on 2018/3/26. */ @Entity public class Hus1 { private int id; private String hname; private Wife1 wife; @Id @Column(name = "id", nullable = false) public int getId() { return id; } public void setId(int id) { this.id = id; } @Basic @Column(name = "hname", nullable = true, length = 10) public String getHname() { return hname; } public void setHname(String hname) { this.hname = hname; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Hus1 hus1 = (Hus1) o; if (id != hus1.id) return false; if (hname != null ? !hname.equals(hus1.hname) : hus1.hname != null) return false; return true; } @Override public int hashCode() { int result = id; result = 31 * result + (hname != null ? hname.hashCode() : 0); return result; } @OneToOne(cascade ={CascadeType.ALL}) @JoinColumn(name = "id", referencedColumnName = "id", nullable = false) public Wife1 getWife() { return wife; } public void setWife(Wife1 wife) { this.wife = wife; } }
Wife1类
package com.weikun.po; import javax.persistence.*; /** * Created by Administrator on 2018/3/26. */ @Entity public class Wife1 { private int id; private String wname; private Hus1 hus1ById; private Hus1 hus; @Id @Column(name = "id", nullable = false) public int getId() { return id; } public void setId(int id) { this.id = id; } @Basic @Column(name = "wname", nullable = true, length = 10) public String getWname() { return wname; } public void setWname(String wname) { this.wname = wname; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Wife1 wife1 = (Wife1) o; if (id != wife1.id) return false; if (wname != null ? !wname.equals(wife1.wname) : wife1.wname != null) return false; return true; } @Override public int hashCode() { int result = id; result = 31 * result + (wname != null ? wname.hashCode() : 0); return result; } @OneToOne @JoinColumn(name = "id", referencedColumnName = "id", nullable = false) public Hus1 getHus1ById() { return hus1ById; } public void setHus1ById(Hus1 hus1ById) { this.hus1ById = hus1ById; } @OneToOne(mappedBy = "wife") public Hus1 getHus() { return hus; } public void setHus(Hus1 hus) { this.hus = hus; } }
对两个表进行操作：
package com.weikun.dao; import com.weikun.po.Hus1; import com.weikun.po.Wife1; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.junit.Test; /** * Created by Administrator on 2018/3/26. */ public class HusDAOImpl { private SessionFactory sf=null; private Configuration configuration=null; public HusDAOImpl(){ configuration=new Configuration().configure("hibernate.cfg.xml"); sf=configuration.buildSessionFactory(); } @Test public void update(){ Session session=sf.openSession(); Transaction trans=session.beginTransaction(); try{ Hus1 hus=session.load(Hus1.class,6); hus.setHname("C"); hus.getWife().setWname("PS"); session.update(hus); trans.commit(); }catch(Exception e){ trans.rollback(); e.printStackTrace(); } session.close(); } @Test public void del(){ Session session=sf.openSession(); Transaction trans=session.beginTransaction(); try{ Hus1 hus=session.load(Hus1.class,1); session.delete(hus); trans.commit(); }catch(Exception e){ trans.rollback(); e.printStackTrace(); } session.close(); } @Test public void add(){ Session session=sf.openSession(); Transaction trans=session.beginTransaction(); try{ Hus1 hus=new Hus1(); hus.setHname("JAVA"); hus.setId(6); Wife1 wif=new Wife1(); wif.setWname("python"); wif.setId(6); hus.setWife(wif); wif.setHus(hus); session.save(hus); trans.commit(); }catch(Exception e){ trans.rollback(); e.printStackTrace(); } session.close(); } @Test public void queryById(){ Session session=sf.openSession(); Hus1 hus=session.load(Hus1.class,1);// System.out.printf("%s-%s",hus.getHname(),hus.getWife().getWname()); Wife1 wife=session.load(Wife1.class,1);// System.out.printf("%s-%s",wife.getWname(),wife.getHus().getHname()); session.close(); } }
二、一对多（父子关系表）
两个表：父亲表（father2）、儿子表（son2），外键为fid，父亲表中属性有fid、fname，儿子表中有属性sid、sname、fid
映射得到两个类：Father2和Son2类
Father2类：
package com.weikun.po; import org.hibernate.annotations.Fetch; import org.hibernate.annotations.FetchMode; import javax.persistence.*; import java.util.HashSet; import java.util.Set; /** * Created by Administrator on 2018/3/26. */ @Entity public class Father2 { private int fid; private String fname; private Set<Son2> sons=new HashSet<Son2>(); @Id @Column(name = "fid", nullable = false) public int getFid() { return fid; } public void setFid(int fid) { this.fid = fid; } @Basic @Column(name = "fname", nullable = true, length = 10) public String getFname() { return fname; } public void setFname(String fname) { this.fname = fname; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Father2 father2 = (Father2) o; if (fid != father2.fid) return false; if (fname != null ? !fname.equals(father2.fname) : father2.fname != null) return false; return true; } @Override public int hashCode() { int result = fid; result = 31 * result + (fname != null ? fname.hashCode() : 0); return result; } @OneToMany(mappedBy = "father",cascade = {CascadeType.ALL}) //@Fetch(FetchMode.JOIN) public Set<Son2> getSons() { return sons; } public void setSons(Set<Son2> sons) { this.sons = sons; } }
Son2类：
package com.weikun.po; import javax.persistence.*; /** * Created by Administrator on 2018/3/26. */ @Entity public class Son2 { private int sid; private String sname; private Father2 father2ByFid; private Father2 father2ByFid_0; private Father2 father; @Id @Column(name = "sid", nullable = false) public int getSid() { return sid; } public void setSid(int sid) { this.sid = sid; } @Basic @Column(name = "sname", nullable = true, length = 10) public String getSname() { return sname; } public void setSname(String sname) { this.sname = sname; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Son2 son2 = (Son2) o; if (sid != son2.sid) return false; if (sname != null ? !sname.equals(son2.sname) : son2.sname != null) return false; return true; } @Override public int hashCode() { int result = sid; result = 31 * result + (sname != null ? sname.hashCode() : 0); return result; } @ManyToOne @JoinColumn(name = "fid", referencedColumnName = "fid") public Father2 getFather() { return father; } public void setFather(Father2 father) { this.father = father; } }
操作父子关系：
package com.weikun.dao; import com.weikun.po.Father2; import com.weikun.po.Son2; import org.hibernate.*; import org.hibernate.cfg.Configuration; import org.hibernate.query.Query; import org.junit.Test; import javax.persistence.Table; import java.util.List; /** * Created by Administrator on 2018/3/26. */ public class FatherDAOImpl { private SessionFactory sf=null; private Configuration configuration=null; public FatherDAOImpl(){ configuration=new Configuration().configure("hibernate.cfg.xml"); sf=configuration.buildSessionFactory(); } @Test public void del(){ Session session=sf.openSession(); Transaction trans=session.beginTransaction(); try { //Son2 s=session.load(Son2.class,6); Father2 s=session.load(Father2.class,6); session.delete(s); trans.commit(); }catch(Exception e){ trans.rollback(); e.printStackTrace(); } session.close(); } public static void main(String[] args) { } @Test public void go(){ Father2 s=query(); s.getSons().forEach(s1->System.out.println(s1.getSname())); } public Father2 query(){ Session session=sf.openSession(); Father2 s=null; try { //Son2 s=session.load(Son2.class,6); s=session.get(Father2.class,6); if(!Hibernate.isInitialized(s.getSons())){//lazy的必须解决方案，访问子表情况 Hibernate.initialize(s.getSons()); } //s.getSons().forEach(s1->System.out.println(s1.getSname())); }catch(Exception e){ e.printStackTrace(); } session.close(); return s; } @Test public void query2(){ Session session=sf.openSession(); Father2 s=null; try { //Son2 s=session.load(Son2.class,6); Query q=session.createQuery("from Father2 as a "); q.setLockMode("a", LockMode.UPGRADE_NOWAIT);//强力锁止 q.setCacheable(true); q.list(); Query q2 =session.createQuery("from Father2 where fid=1"); q2.setCacheable(true); q2.list(); }catch(Exception e){ e.printStackTrace(); } session.close(); } @Test public void query1(){ Session session=sf.openSession(); try { Son2 s=session.load(Son2.class,6); System.out.println(s.getFather().getFname()); }catch(Exception e){ e.printStackTrace(); } session.close(); } @Test public void add(){ Session session=sf.openSession(); Transaction trans=session.beginTransaction(); try { Father2 f=new Father2(); f.setFid(6); f.setFname("JASON"); Son2 s=new Son2(); s.setSid(6); s.setSname("ROSE"); s.setFather(f); Son2 s1=new Son2(); s1.setSid(7); s1.setSname("MARY"); s1.setFather(f); f.getSons().add(s); f.getSons().add(s1); session.save(f); trans.commit(); }catch(Exception e){ trans.rollback(); e.printStackTrace(); } session.close(); } }
三、多对多（老师学生关系）
三个表只映射两个，tea、stu，而管理两个表关系的teastu表不用映射导入
映射tea和stu表得到Stu类和Tea类
Tea类：
package com.weikun.po; import org.hibernate.annotations.Cascade; import javax.persistence.*; import java.util.HashSet; import java.util.Set; /** * Created by Administrator on 2018/3/26. */ @Entity public class Tea { private int tid; private String tname; private Set<Stu> stus=new HashSet<>(); @Id @Column(name = "tid", nullable = false) public int getTid() { return tid; } public void setTid(int tid) { this.tid = tid; } @Basic @Column(name = "tname", nullable = true, length = 10) public String getTname() { return tname; } public void setTname(String tname) { this.tname = tname; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Tea tea = (Tea) o; if (tid != tea.tid) return false; if (tname != null ? !tname.equals(tea.tname) : tea.tname != null) return false; return true; } @Override public int hashCode() { int result = tid; result = 31 * result + (tname != null ? tname.hashCode() : 0); return result; } @Cascade(value=org.hibernate.annotations.CascadeType.SAVE_UPDATE) @ManyToMany() @JoinTable(name = "teastu", catalog = "res", schema = "res", joinColumns = @JoinColumn(name = "tid", referencedColumnName = "tid", nullable = false), inverseJoinColumns = @JoinColumn(name = "sid", referencedColumnName = "sid", nullable = false)) public Set<Stu> getStus() { return stus; } public void setStus(Set<Stu> stus) { this.stus = stus; } }
Stu类：
package com.weikun.po; import javax.persistence.*; import java.util.HashSet; import java.util.Set; /** * Created by Administrator on 2018/3/26. */ @Entity public class Stu { private int sid; private String sname; private Set<Tea> teas=new HashSet<>(); @Id @Column(name = "sid", nullable = false) public int getSid() { return sid; } public void setSid(int sid) { this.sid = sid; } @Basic @Column(name = "sname", nullable = true, length = 10) public String getSname() { return sname; } public void setSname(String sname) { this.sname = sname; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Stu stu = (Stu) o; if (sid != stu.sid) return false; if (sname != null ? !sname.equals(stu.sname) : stu.sname != null) return false; return true; } @Override public int hashCode() { int result = sid; result = 31 * result + (sname != null ? sname.hashCode() : 0); return result; } @ManyToMany(mappedBy = "stus") public Set<Tea> getTeas() { return teas; } public void setTeas(Set<Tea> teas) { this.teas = teas; } }
操纵师生关系的类：
package com.weikun.dao; import com.weikun.po.Father2; import com.weikun.po.Stu; import com.weikun.po.Tea; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.junit.Test; /** * Created by Administrator on 2018/3/26. */ public class TeaDAOImpl { private SessionFactory sf=null; private Configuration configuration=null; public TeaDAOImpl(){ configuration=new Configuration().configure("hibernate.cfg.xml"); sf=configuration.buildSessionFactory(); } @Test public void del(){ Session session=sf.openSession(); Transaction trans=session.beginTransaction(); try { Tea t=session.load(Tea.class,6); session.delete(t); trans.commit(); }catch(Exception e){ trans.rollback(); e.printStackTrace(); } session.close(); } @Test public void add(){ Session session=sf.openSession(); Transaction trans=session.beginTransaction(); try { Tea t=new Tea(); t.setTid(6); t.setTname("MARY"); Tea t1=new Tea(); t1.setTid(7); t1.setTname("NICK"); Stu s1=new Stu(); s1.setSid(10); s1.setSname("S1"); s1.getTeas().add(t); s1.getTeas().add(t1); Stu s2=new Stu(); s2.setSid(11); s2.setSname("S2"); s2.getTeas().add(t); s2.getTeas().add(t1); t1.getStus().add(s1); t1.getStus().add(s2); t.getStus().add(s1); t.getStus().add(s2); session.save(t); session.save(t1); trans.commit(); }catch(Exception e){ trans.rollback(); e.printStackTrace(); } session.close(); } }
