hibernate二级和查询缓存使用

二级缓存

一。先导入解压后hibernate-release-4.2.8.Final\lib\optional\ehcache目录下的jar包
ehcache-core-2.4.3.jar
hibernate-ehcache-4.2.8.Final.jar
slf4j-api-1.6.1.jar

二。配置hibernate.cfg.xml

		<property name="hibernate.cache.use_second_level_cache">true</property>
		<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property> 
		<property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property>
		

三。拷贝下载包\hibernate-release-4.2.8.Final\project\hibernate-ehcache\bin项目目录下的ehcache.xml文件至项目根目录下

四。在实体类上加上@Cache注释

@Entity
@Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
public class Student{
	private int id;
	private String name;
	private Set<Teacher> students =new HashSet<Teacher>();
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	@ManyToMany(mappedBy="students")
	public Set<Teacher> getStudents() {
		return students;
	}

	public void setStudents(Set<Teacher> students) {
		this.students = students;
	}

	public String getName() {
		return name;
	}
	public void setId(int id) {
		this.id = id;
	}
	public void setName(String name) {
		this.name = name;
	}
}

五，测试

public class OneToOneORMappingTest {
	public static void main(String[] args) {
		Configuration cfg = new AnnotationConfiguration().configure("/hibernate.cfg.xml");
		SessionFactory sf = cfg.buildSessionFactory();
		Session session = sf.openSession();
		session.beginTransaction();
		Student student =(Student) session.load(Student.class, 0);
		
		System.out.println(student.getName());
		session.getTransaction().commit();
		session.close();
		
		Session session2 = sf.openSession();
		session2.beginTransaction();
		//查询
		Student student2 =(Student) session2.load(Student.class,0);
		System.out.println(student2.getName());
		session2.getTransaction().commit();
		session2.close();
		sf.close();

	}

}

测试结果,只发出一条语句，输出两次结果

Hibernate: 
    select
        student0_.id as id1_0_0_,
        student0_.name as name2_0_0_ 
    from
        Student student0_ 
    where
        student0_.id=?
zhangsan
zhangsan

查询缓存
依赖二级缓存
一。配置hibernate.cfg.xml，打开查询缓存

<property name="hibernate.cache.use_query_cache">true</property>	

二。测试，查询时注意加setCacheable(true)

public class OneToOneORMappingTest {
	public static void main(String[] args) {
		Configuration cfg = new AnnotationConfiguration().configure("/hibernate.cfg.xml");
		SessionFactory sf = cfg.buildSessionFactory();
		Session session = sf.openSession();
		session.beginTransaction();
		//查询
		List<Student> result = session.createQuery("from Student").setCacheable(true).list();
		for(Student s :result){
			System.out.println(s.getName());
		}
		session.getTransaction().commit();
		session.close();
		
		Session session2 = sf.openSession();
		session2.beginTransaction();
		//查询
		List result2 = session2.createQuery("from Student").setCacheable(true).list();

		session2.getTransaction().commit();
		session2.close();
		sf.close();
		
	}
}

测试结果：只发出一条sql语句