Hibernate 内连接和左外连接

package test;

import java.util.List;

import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;

import util.HibernateSessionFactory;
import entity.Student;
import entity.Teacher;

public class TestInnerJoin {
	public static void main(String[] args) {
		jion();// 内连接
		leftJoin();// 左外连接
	}

	private static void jion() {
		// 打开Session
		Session session = HibernateSessionFactory.getSession();
		// 内连接 hql 语句
		String hql = "from Student s inner join s.teacher";
		try {
			// 实例查询对象
			Query query = session.createQuery(hql);
			// 获取列表
			List<Object[]> lists = query.list();
			// 遍历列表
			for (Object[] list : lists) {
				// 判断如果是 Student
				if (list[0] instanceof Student) {
					// 获取 Student 的列表
					Student student = (Student) list[0];
					System.out.print(student.getId() + " " + student.getName());
				}
				// 判断如果是 Teacher
				if (list[1] instanceof Teacher) {
					// 获取 Teacher 的列表
					Teacher teacher = (Teacher) list[1];
					System.out.println(teacher.getId() + " "
							+ teacher.getName() + " ");
				}
			}
			System.out.println("成功");
		} catch (HibernateException e) {
			e.printStackTrace();
		} finally {
			// 关闭 session，释放资源
			HibernateSessionFactory.closeSession();
		}
	}

	private static void leftJoin() {
		// 打开Session
		Session session = HibernateSessionFactory.getSession();
		// 内连接 hql 语句
		String hql = "from Student s left join s.teacher";
		try {
			// 实例查询对象
			Query query = session.createQuery(hql);
			// 获取列表
			List<Object[]> lists = query.list();
			// 遍历列表
			for (Object[] list : lists) {
				// 判断如果是 Student
				if (list[0] instanceof Student) {
					// 获取 Student 的列表
					Student student = (Student) list[0];
					System.out.print(student.getId() + " " + student.getName());
				}
				// 判断如果是 Teacher
				if (list[1] instanceof Teacher) {
					// 获取 Teacher 的列表
					Teacher teacher = (Teacher) list[1];
					System.out.println(teacher.getId() + " "
							+ teacher.getName() + " ");
				}
			}
			System.out.println("成功");
		} catch (HibernateException e) {
			e.printStackTrace();
		} finally {
			// 关闭 session，释放资源
			HibernateSessionFactory.closeSession();
		}
	}
}

 

效果图：