Hibernate（三）

注解高级（原文再续书接上一回）

5.双向关联

A.一对一

package com.rong.entity;

import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="t_citizen")
public class Citizen {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;
    private String name;
    private int sex; 
    @OneToOne(targetEntity=IDcard.class,fetch=FetchType.LAZY,mappedBy="citizen") // 不维护关联关系(主表)
    private IDcard iDcard;                                    //由iDcard对象的成员变量citizen来维护
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getSex() {
        return sex;
    }
    public void setSex(int sex) {
        this.sex = sex;
    }
    public IDcard getiDcard() {
        return iDcard;
    }
    public void setiDcard(IDcard iDcard) {
        this.iDcard = iDcard;
    }
    @Override
    public String toString() {
        return "Citizen [id=" + id + ", name=" + name + ", sex=" + sex + ", iDcard=" + iDcard + "]";
    }
}

package com.rong.entity;

import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="t_idcard")
public class IDcard {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int cardid;
    private String name;
    private String addr;
    @OneToOne(targetEntity=Citizen.class,fetch=FetchType.LAZY) // 维护关联关系(从表)
    @JoinColumn(name="t_id",referencedColumnName="id",unique=true)//生成外键列，参考citizen的id
    private Citizen citizen;
    public int getCardid() {
        return cardid;
    }
    public void setCardid(int cardid) {
        this.cardid = cardid;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAddr() {
        return addr;
    }
    public void setAddr(String addr) {
        this.addr = addr;
    }
    public Citizen getCitizen() {
        return citizen;
    }
    public void setCitizen(Citizen citizen) {
        this.citizen = citizen;
    }
    @Override
    public String toString() {
        return "IDcard [cardid=" + cardid + ", name=" + name + ", addr=" + addr + ", citizen=" + citizen + "]";
    }
}

package com.rong.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.junit.Test;

import com.rong.entity.Citizen;
import com.rong.entity.IDcard;

public class HibernateTest {
    @Test
    public void test1(){
        Configuration configuration=new Configuration().configure();
        ServiceRegistry serviceRegistry=new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
        SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
        Session session = sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();
        
        Citizen citizen=new Citizen();
        citizen.setName("容杰龙");
        citizen.setSex(0);
        IDcard iDcard=new IDcard();
        iDcard.setAddr("广东");
        iDcard.setCitizen(citizen);
        
        session.save(citizen);
        session.save(iDcard);
        //查找
        Citizen person = (Citizen) session.get(Citizen.class, 1);
        System.out.println(person);
        IDcard card = (IDcard) session.get(IDcard.class, 1);
        System.out.println(card);
        transaction.commit();
        session.close();
        sessionFactory.close();
    }
}

B.一对多（多的那端维护）

package com.rong.entity;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="t_teacher")
public class Teacher {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int tid;
    private String tname;
    //一的一端(主表)
    @OneToMany(targetEntity=Student.class // 指定关联的持久化
            ,fetch=FetchType.LAZY // 延迟加载
            ,cascade={CascadeType.REMOVE} // 级联删除(级联到关联的持久化类)
            ,orphanRemoval=true // 删除孤儿记录
            ,mappedBy="tea"//关联关系(外键列由从表维护), 写关联的持久化中哪个属性引用了它自己
            )
    private Set<Student> stu=new HashSet<Student>();
    public int getTid() {
        return tid;
    }
    public void setTid(int tid) {
        this.tid = tid;
    }
    public String getTname() {
        return tname;
    }
    public void setTname(String tname) {
        this.tname = tname;
    }
    public Set<Student> getStu() {
        return stu;
    }
    public void setStu(Set<Student> stu) {
        this.stu = stu;
    }
    @Override
    public String toString() {
        return "Teacher [tid=" + tid + ", tname=" + tname + ", stu=" + stu + "]";
    }
}

package com.rong.entity;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name="t_student")
public class Student {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int sid;
    private String sname;
    //多的一端 (从表，有外键)
    @ManyToOne(targetEntity=Teacher.class// 指定关联的持久化类
                ,fetch=FetchType.LAZY // 延迟加载
                ,cascade=CascadeType.REMOVE// 级联删除
                )
    //生成外键列
    @JoinColumn(name="t_id",referencedColumnName="tid")
    private Teacher tea;
    public int getSid() {
        return sid;
    }
    public void setSid(int sid) {
        this.sid = sid;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public Teacher getTea() {
        return tea;
    }
    public void setTea(Teacher tea) {
        this.tea = tea;
    }
    @Override
    public String toString() {
        return "Student [sid=" + sid + ", sname=" + sname + ", tea=" + tea + "]";
    }
}

package com.rong.test;

import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.junit.Test;

import com.rong.entity.Student;
import com.rong.entity.Teacher;

public class HibernateTest {
    @Test
    public void test1(){
        Configuration configuration=new Configuration().configure();
        ServiceRegistry serviceRegistry=new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
        SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
        Session session = sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();
/*        //t_teacher 这个表是主表
        Teacher teacher=new Teacher();
        teacher.setTname("局长");
        //t_student 是从表（有外键的是从表，需要维护关联关系）
        Student student1=new Student();
        student1.setSname("容杰龙");
        student1.setTea(teacher);
        Student student2=new Student();
        student2.setSname("古月哥欠");
        student2.setTea(teacher);
        //保存的时候，必须先保存主表，后保存从表
        session.save(teacher);
        session.save(student1);
        session.save(student2);*/
        //查找
        Teacher tea=(Teacher) session.get(Teacher.class, 1);
        System.out.println(tea.getTname());
        Set<Student> set = tea.getStu();
        for (Student student : set) {
            System.out.println(student.getSid()+":"+student.getSname());
        }
        
        transaction.commit();
        session.close();
        sessionFactory.close();
    }
}

C.多对多

package com.rong.entity;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

@Entity
@Table(name="t_teacher")
public class Teacher {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int tid;
    private String tname;
    //多的一端
    @ManyToMany(targetEntity=Student.class
                ,fetch=FetchType.LAZY
                ,mappedBy="tea"// 老师这边不维护关联关系 (不用生成中间表)
                )
    private Set<Student> stu=new HashSet<Student>();
    public int getTid() {
        return tid;
    }
    public void setTid(int tid) {
        this.tid = tid;
    }
    public String getTname() {
        return tname;
    }
    public void setTname(String tname) {
        this.tname = tname;
    }
    public Set<Student> getStu() {
        return stu;
    }
    public void setStu(Set<Student> stu) {
        this.stu = stu;
    }
    @Override
    public String toString() {
        return "Teacher [tid=" + tid + ", tname=" + tname + ", stu=" + stu + "]";
    }
}

package com.rong.entity;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

@Entity
@Table(name="t_student")
public class Student {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int sid;
    private String sname;
    //多的一端
    @ManyToMany(targetEntity=Teacher.class,fetch=FetchType.LAZY)
    //生成中间表
    @JoinTable(name="tea_stu" // 中间表的表名
                // @ManyToMany注解中没有加mappedBy表的主键列
                ,joinColumns={@JoinColumn(name="sid",referencedColumnName="sid")}
                // @ManyToMany注解中加了mappedBy属性的表的主键列
                ,inverseJoinColumns={@JoinColumn(name="tid",referencedColumnName="tid")})
    private Set<Teacher> tea=new HashSet<Teacher>();
    public int getSid() {
        return sid;
    }
    public void setSid(int sid) {
        this.sid = sid;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public Set<Teacher> getTea() {
        return tea;
    }
    public void setTea(Set<Teacher> tea) {
        this.tea = tea;
    }
    @Override
    public String toString() {
        return "Student [sid=" + sid + ", sname=" + sname + ", tea=" + tea + "]";
    }
}

package com.rong.test;

import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.junit.Test;

import com.rong.entity.Student;
import com.rong.entity.Teacher;

public class HibernateTest {
    @Test
    public void test1(){
        Configuration configuration=new Configuration().configure();
        ServiceRegistry serviceRegistry=new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
        SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
        Session session = sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();
/*        //t_teacher 这个表是主表
        Teacher teacher1=new Teacher();
        teacher1.setTname("陈局长");
        Teacher teacher2=new Teacher();
        teacher2.setTname("容部长");
        //t_student 是从表（有外键的是从表，需要维护关联关系）
        Student student1=new Student();
        student1.setSname("容杰龙");
        student1.getTea().add(teacher1);
        student1.getTea().add(teacher2);
        Student student2=new Student();
        student2.setSname("古月哥欠");
        student2.getTea().add(teacher1);
        student2.getTea().add(teacher2);
        //保存的时候，必须先保存主表，后保存从表
        session.save(teacher1);
        session.save(teacher2);
        session.save(student1);
        session.save(student2);
*/        
        //查找
        Teacher tea=(Teacher) session.get(Teacher.class, 1);
        System.out.println(tea.getTname());
        Set<Student> set = tea.getStu();
        for (Student student : set) {
            System.out.println(student.getSid()+":"+student.getSname());
        }
        Student student=(Student) session.get(Student.class, 1);
        System.out.println(student.getSname());
        Set<Teacher> set2 = student.getTea();
        for (Teacher teacher : set2) {
            System.out.println(teacher.getTid()+":"+teacher.getTname());
        }
        transaction.commit();
        session.close();
        sessionFactory.close();
    }
}