hibernate配置单向一对多和多对一的关系

深藏阁楼爱情的钟 2022-07-24 06:11 186阅读 0赞

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
    <!DOCTYPE hibernate-configuration PUBLIC
            "-//Hibernate/Hibernate Configuration DTD//EN"
            "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    <hibernate-configuration>
        <session-factory>
            <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
            <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
            <property name="connection.username">root</property>
            <property name="connection.password">q7231012</property>
            
            <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    
            
            <property name="show_sql">true</property>
            
            <property name="format_sql">true</property>
            
            <property name="hbm2ddl.auto">update</property>
    
            
            <property name="default_schema">hibernate</property>
    
            
            <property name="hibernate.current_session_context_class">thread</property>
    
            <mapping resource="entity/Students.hbm.xml"/>
            <mapping class="entity.Students"/>
            <mapping resource="entity/Grade.hbm.xml"/>
            <mapping class="entity.Grade"/>
            <mapping resource="entity/Student.hbm.xml"/>
            <mapping class="entity.Student"/>
    
    
            
            
        </session-factory>
    </hibernate-configuration>

Student.java

package entity;
    
    import javax.persistence.Basic;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.Id;
    
    /**
     * Created by raid on 2016/5/15.
     */
    @Entity
    public class Student {
        private Integer sid;
        private String sname;
        private String sex;
        //在多方定义一个一方的引用
        private Grade grade;
    
        public Student() {
        }
    
        public Student(String sname, String sex) {
            this.sname = sname;
            this.sex = sex;
        }
    
        public Student(Integer sid, String sname, String sex) {
            this.sid = sid;
            this.sname = sname;
            this.sex = sex;
        }
    
        @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 = "sex")
        public String getSex() {
            return sex;
        }
    
        public void setSex(String sex) {
            this.sex = sex;
        }
    
        public Grade getGrade() {
            return grade;
        }
    
        public void setGrade(Grade grade) {
            this.grade = grade;
        }
    
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
    
            Student student = (Student) o;
    
            if (sid != null ? !sid.equals(student.sid) : student.sid != null) return false;
            if (sname != null ? !sname.equals(student.sname) : student.sname != null) return false;
            if (sex != null ? !sex.equals(student.sex) : student.sex != 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 + (sex != null ? sex.hashCode() : 0);
            return result;
        }
    }

Student.hbm.xml

<?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.Student" table="student" schema="hibernate">
            <id name="sid" column="sid">
                <generator class="native"/>
            </id>
            <property name="sname" column="sname"/>
            <property name="sex" column="sex"/>
    
            
            <many-to-one name="grade" class="entity.Grade" column="gid" />
    
        </class>
    
    </hibernate-mapping>

Grade.java

package entity;
    
    import javax.persistence.Basic;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.Id;
    import java.util.HashSet;
    import java.util.Set;
    
    /**
     * Created by raid on 2016/5/15.
     */
    @Entity
    public class Grade {
        private Integer gid;
        private String gname;
        private String gdesc;
    
        /*
        一对多的关系，在一方定义多方的集合,可以使用Set和List集合
        1.元素不允许重复就使用Set集合
        2.允许重复使用List集合
         */
        private Set<Student> students = new HashSet<>();
    
        public Grade() {
        }
    
        public Grade(String gname, String gdesc) {
            this.gname = gname;
            this.gdesc = gdesc;
        }
    
        public Grade(Integer gid, String gname, String gdesc, Set<Student> students) {
            this.gid = gid;
            this.gname = gname;
            this.gdesc = gdesc;
            this.students = students;
        }
    
        @Id
        @Column(name = "gid")
        public Integer getGid() {
            return gid;
        }
    
        public void setGid(Integer gid) {
            this.gid = gid;
        }
    
        @Basic
        @Column(name = "gname")
        public String getGname() {
            return gname;
        }
    
        public void setGname(String gname) {
            this.gname = gname;
        }
    
        @Basic
        @Column(name = "gdesc")
        public String getGdesc() {
            return gdesc;
        }
    
        public void setGdesc(String gdesc) {
            this.gdesc = gdesc;
        }
    
        public Set<Student> getStudents() {
            return students;
        }
    
        public void setStudents(Set<Student> students) {
            this.students = students;
        }
    
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
    
            Grade grade = (Grade) o;
    
            if (gid != null ? !gid.equals(grade.gid) : grade.gid != null) return false;
            if (gname != null ? !gname.equals(grade.gname) : grade.gname != null) return false;
            if (gdesc != null ? !gdesc.equals(grade.gdesc) : grade.gdesc != null) return false;
    
            return true;
        }
    
        @Override
        public int hashCode() {
            int result = gid != null ? gid.hashCode() : 0;
            result = 31 * result + (gname != null ? gname.hashCode() : 0);
            result = 31 * result + (gdesc != null ? gdesc.hashCode() : 0);
            return result;
        }
    }

Grade.hbm.xml

<?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.Grade" table="grade" schema="hibernate">
            <id name="gid" column="gid">
                <generator class="native"/>
            </id>
            <property name="gname" column="gname"/>
            <property name="gdesc" column="gdesc"/>
            
            <set name="students" table="student" inverse="true" cascade="save-update">
                
                <key column="gid" />
                <one-to-many class="entity.Student" />
            </set>
        </class>
    </hibernate-mapping>

Grade2StudentLogic.java

package dao;
    
    import entity.Grade;
    import entity.Student;
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    import util.HibernateUtil;
    
    import java.util.Set;
    
    /**
     * Created by raid on 2016/5/15.
     */
    public class Grade2StudentLogic {
    
        public void add() {
            Grade g = new Grade("计算机", "软件工程");
            Student stu1 = new Student("小小黑", "男");
            Student stu2 = new Student("raid", "女");
            //如果希望在学生表中添加对应的班级编号，需要在班级中添加学生，建立关联关系
            g.getStudents().add(stu1);
            g.getStudents().add(stu2);
    
            Session session = HibernateUtil.getSession();
            Transaction transaction = session.beginTransaction();
            session.save(g);
            session.save(stu1);
            session.save(stu2);
            transaction.commit();
    
        }
    
        public void findStudentsByGrade() {
            Session session = HibernateUtil.getSession();
            Transaction transaction = session.beginTransaction();
            Grade grade = (Grade) session.get(Grade.class, 5);
            System.out.println(grade.getGname() + "," + grade.getGdesc());
    
            Set<Student> students = grade.getStudents();
            for (Student stu : students) {
                System.out.println(stu.getSname() + "," + stu.getSex());
            }
            transaction.commit();
        }
    
        public void update() {
            Grade g = new Grade("计算机二", "软件工程二");
            Session session = HibernateUtil.getSession();
            Transaction transaction = session.beginTransaction();
            Student stu = (Student) session.get(Student.class, 1);
            g.getStudents().add(stu);
            session.save(g);
            transaction.commit();
    
        }
    
        public void delete() {
            Session session = HibernateUtil.getSession();
            Transaction transaction = session.beginTransaction();
            Student stu = (Student) session.get(Student.class, 2);
            session.delete(stu);
            transaction.commit();
    
        }
    
    
        /**
         * Created by raid on 2016/5/15.
         * 单向多对一(学生->班级)
         */
        public void save() {
            Grade g = new Grade("Java三班", "Java软件开发三班");
            Student stu1 = new Student("学生1", "女");
            Student stu2 = new Student("学生2", "男");
            //设置关联关系
            g.getStudents().add(stu1);
            g.getStudents().add(stu2);
            stu1.setGrade(g);
            stu2.setGrade(g);
    
            Session session = HibernateUtil.getSession();
            Transaction transaction = session.beginTransaction();
            session.save(g);
    //        session.save(stu1);
    //        session.save(stu2);
            transaction.commit();
        }
    
        public void findGradeByStudent() {
            Session session = HibernateUtil.getSession();
            Transaction transaction = session.beginTransaction();
            Student stu = (Student) session.get(Student.class, 9);
            System.out.println(stu.getSid() + "," + stu.getSname() + "," + stu.getSex());
            Grade g = stu.getGrade();
            System.out.println(g.getGid() + "," + g.getGname() + "," + g.getGdesc());
        }
    
    }

OneToManyTest.java

package dao;
    
    /**
     * Created by raid on 2016/5/15.
     */
    public class OneToManyTest {
    
        public static void main(String[] args) {
            Grade2StudentLogic logic = new Grade2StudentLogic();
    //        logic.add();
    //        logic.findStudentsByGrade();
    //        logic.update();
            logic.delete();
        }
    
    }

ManyToOneTest.java

package dao;
    
    import entity.Grade;
    import entity.Student;
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    import util.HibernateUtil;
    
    
    public class ManyToOneTest {
    
        public static void main(String[] args) {
            Grade2StudentLogic logic = new Grade2StudentLogic();
    //        logic.save();
            logic.findGradeByStudent();
        }
    
    }