Mybatis——二级缓存

一级缓存
获得结果时存入
SqlSession级别的。
默认开启。

二级缓存
会话关闭时存入
应用级别的。
需要手动开启配置。

同一个Session：

@Test
public void f1() throws IOException {
	InputStream is = Resources.getResourceAsStream("mybatis.xml");
	SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
	SqlSession s1 = factory.openSession();
	StudentMapper m1 = s1.getMapper(StudentMapper.class);
	System.out.println(m1.findById(1));
	System.out.println(m1.findById(1));
	s1.close();
}

测试结果：

不同的Session：

@Test
public void f1() throws IOException {
	InputStream is = Resources.getResourceAsStream("mybatis.xml");
	SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
	SqlSession s1 = factory.openSession();
	StudentMapper m1 = s1.getMapper(StudentMapper.class);
	System.out.println(m1.findById(1));
	s1.close();
	SqlSession s2 = factory.openSession();
	StudentMapper m2 = s2.getMapper(StudentMapper.class);
	System.out.println(m2.findById(1));
	s2.close();
}

测试结果：

全局配置Mapper配置实体类实现Serializable

全局配置

Mapper配置

几个属性：
eviction：回收策略
LRU（默认）
FIFO
SOFT
WEAK

flushInterval：自动清空间隔秒，默认不清空

readOnly：是否会变动

size：缓存数量

实体类实现

@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class Student implements Serializable {
	private Integer id;
	private String name;
	private Integer age;
}

测试代码：

@Test
public void f1() throws IOException {
	InputStream is = Resources.getResourceAsStream("mybatis.xml");
	SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
	SqlSession s1 = factory.openSession();
	StudentMapper m1 = s1.getMapper(StudentMapper.class);
	System.out.println(m1.findById(1));
	s1.close();
	SqlSession s2 = factory.openSession();
	StudentMapper m2 = s2.getMapper(StudentMapper.class);
	System.out.println(m2.findById(1));
	s2.close();
}

测试结果：