<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!--

    Mapping file autogenerated by MyEclipse Persistence Tools

-->

<hibernate-mapping>

    <class name="entity.Project" table="PROJECT" schema="RENT">

        <id name="proid" type="java.lang.Integer">

            <column name="PROID" precision="6" scale="0" />

            <generator class="assigned" />

        </id>

        <property name="proname" type="java.lang.String">

            <column name="PRONAME" length="100" not-null="true" />

        </property>

        <set name="employees" table="PROEMP" schema="RENT" cascade="save-update">

            <key>

                <column name="RPROID" precision="6" scale="0" not-null="true" />

            </key>

            <many-to-many entity-name="entity.Employee">

                <column name="REMPID" precision="6" scale="0" not-null="true" />

            </many-to-many>

        </set>

    </class>

</hibernate-mapping>

package Test;

import static org.junit.Assert.*;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.junit.Test;

import entity.Employee;

import entity.Project;

import util.HibernateSessionFactory;

public class Test5 {

    //多对多

    @SuppressWarnings("unchecked")

    @Test

    public void test1() {

        //一定要在配置中加级联保存的配置cascade="save-update"

        Session session = HibernateSessionFactory.getSession();

        Transaction tx=session.beginTransaction();

        try {

            Employee employee1 = new Employee(4, "duhe");

            Employee employee2 = new Employee(5, "赵六");

            Project project1 = new Project(4, "4号项目");

            Project project2 = new Project(5, "5号项目");

            //创建关联关系

            project1.getEmployees().add(employee1);

            project1.getEmployees().add(employee2);

            employee1.getProjects().add(project1);

            employee2.getProjects().add(project1);

            project2.getEmployees().add(employee1);

            employee1.getProjects().add(project2);

            session.save(project1);

            session.save(project2);

            tx.commit();

            System.out.println("新增成功");

        } catch (Exception e) {

            e.printStackTrace();

            tx.rollback();

            System.out.println("新增失败");

        }finally{

            session.close();

        }

    }

}

package Test;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Set;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.junit.Test;

import entity.Dept;

import entity.Emp;

import util.HibernateSessionFactory;

public class Test33 {

    // 级联增加

    @Test

    public void test1() {

        Session session = HibernateSessionFactory.getSession();

        Transaction tx=session.beginTransaction();

        try {

            //创建部门

            Dept dept=new Dept();

            dept.setDeptno(50);

            dept.setDname("行政部");

            dept.setLoc("china");

            //创建员工

            Emp emp1=new Emp();

            emp1.setEmpno((short)8001);

            emp1.setEname("liujuan");

            emp1.setJob("吃饭");

            emp1.setSal(9000D);

            Emp emp2=new Emp();

            emp2.setEmpno((short)8002);

            emp2.setEname("duheyu");

            emp2.setJob("睡觉");

            emp2.setSal(1000D);

            //创建员工与部门关联关系

            Set<Emp> emps=new HashSet<Emp>();

            emps.add(emp1);

            emps.add(emp2);

            dept.setEmps(emps);

            emp1.setDept(dept);

            emp2.setDept(dept);

            //增加部门

            session.save(dept);

            tx.commit();

        } catch (Exception e) {

            tx.rollback();

        }

    }

    // 级联删除

    @Test

    public void test2() {

        Session session = HibernateSessionFactory.getSession();

        Transaction tx=session.beginTransaction();

        try {

            /*Dept dept=new Dept();

            dept.setDeptno(50);*/

            //删除一个持久化对象

            Dept dept=(Dept) session.get(Dept.class, 50);

            session.delete(dept);

            tx.commit();

            System.out.println("删除成功");

        } catch (Exception e) {

            tx.rollback();

            System.out.println("删除失败");

        }

    }

    // 级联查询

    @Test

    public void test3() {

        Session session = HibernateSessionFactory.getSession();

        try {

            Dept dept = (Dept) session.get(Dept.class, 30);

            Set<Emp> emps= dept.getEmps();

            for (Emp emp : emps) {

                System.out.println(emp.getEname()+"\t"+emp.getDept().getDeptno()+"\t"+emp.getSal());

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    //lazy属性：一对多。在一方配置

    @Test

    public void test4() {

        Session session = HibernateSessionFactory.getSession();

        try {

            //没有用到emp，默认延迟加载 Dept.hbm.xml set中默认是配置lasy="true"，延迟加载

            Dept dept = (Dept) session.get(Dept.class, 30);

            Set<Emp> emps= dept.getEmps();

            //用到了才会去查询

            for (Emp emp : emps) {

                System.out.println(emp.getEname()+"\t"+emp.getDept().getDeptno()+"\t"+emp.getSal());

            }

            //加强延迟加载，使用于聚合函数查询中

            System.out.println(emps.size());//统计一共有几条，要有select count(*)语句

            //因为上面for循环查过一次，所以这里再统计，就不会再查一次。

            //如果不写for循环，只输出总数，那么也会是2条语句，不会查询所有信息，只输出聚合函数的查询语句

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}