Mybatis基于注解开启使用二级缓存

  关于Mybatis的一级缓存和二级缓存的概念以及理解可以参照前面文章的介绍。前文连接:https://www.cnblogs.com/hopeofthevillage/p/11427438.html,上文中二级缓存使用的是xml方式的实现,本文主要是补充一下Mybatis中基于注解的二级缓存的开启使用方法。

  1.在Mybatis的配置文件中开启二级缓存

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<!--开启全局的懒加载-->
<setting name="lazyLoadingEnabled" value="true"/>
<!--&lt;!&ndash;关闭立即加载,其实不用配置,默认为false&ndash;&gt;-->
<!--<setting name="aggressiveLazyLoading" value="false"/>-->
<!--开启Mybatis的sql执行相关信息打印-->
<setting name="logImpl" value="STDOUT_LOGGING" />
<!--默认是开启的,为了加强记忆,还是手动加上这个配置-->
<setting name="cacheEnabled" value="true"/>
</settings>
<typeAliases>
<typeAlias type="com.example.domain.User" alias="user"/>
<package name="com.example.domain"/>
</typeAliases>
<environments default="test">
<environment id="test">
<!--配置事务-->
<transactionManager type="jdbc"></transactionManager>
<!--配置连接池-->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/test1"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<mappers>
<package name="com.example.dao"/>
</mappers>
</configuration>

  开启缓存 <setting name="cacheEnabled" value="true"/>,为了查看Mybatis中查询的日志,添加 <setting name="logImpl" value="STDOUT_LOGGING" />开启日志的配置。

  2.领域类以及Dao

public class User implements Serializable{
private Integer userId;
private String userName;
private Date userBirthday;
private String userSex;
private String userAddress;
private List<Account> accounts;
省略get和set方法......
} import com.example.domain.User;
import org.apache.ibatis.annotations.*;
import org.apache.ibatis.mapping.FetchType; import java.util.List;
@CacheNamespace(blocking = true)
public interface UserDao {
/**
* 查找所有用户
* @return
*/
@Select("select * from User")
@Results(id = "userMap",value = {@Result(id = true,column = "id",property = "userId"),
@Result(column = "username",property = "userName"),
@Result(column = "birthday",property = "userBirthday"),
@Result(column = "sex",property = "userSex"),
@Result(column = "address",property = "userAddress"),
@Result(column = "id",property = "accounts",many = @Many(select = "com.example.dao.AccountDao.findAccountByUid",fetchType = FetchType.LAZY))
})
List<User> findAll(); /**
* 保存用户
* @param user
*/
@Insert("insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})")
void saveUser(User user); /**
* 更新用户
* @param user
*/
@Update("update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id}")
void updateUser(User user); /**
* 删除用户
* @param id
*/
@Delete("delete from user where id=#{id}")
void deleteUser(Integer id); /**
* 查询用户根据ID
* @param id
* @return
*/
@Select("select * from user where id=#{id}")
@ResultMap(value = {"userMap"})
User findById(Integer id); /**
* 根据用户名称查询用户
* @param name
* @return
*/
// @Select("select * from user where username like #{name}")
@Select("select * from user where username like '%${value}%'")
List<User> findByUserName(String name); /**
* 查询用户数量
* @return
*/
@Select("select count(*) from user")
int findTotalUser();
}

  3.在对应的Dao类上面增加注释以开启二级缓存 

  @CacheNamespace(blocking = true)

  4.测试

public class UserCacheTest {

    private InputStream in;
private SqlSessionFactory sqlSessionFactory; @Before
public void init()throws Exception{
in = Resources.getResourceAsStream("SqlMapConfig.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(in); }
@After
public void destory()throws Exception{
in.close();
}
@Test
public void testFindById(){
//第一查询
SqlSession sqlSession1 = sqlSessionFactory.openSession();
UserDao userDao1 = sqlSession1.getMapper(UserDao.class);
User user1 = userDao1.findById(41);
System.out.println(user1);
//关闭一级缓存
sqlSession1.close();
//第二次查询
SqlSession sqlSession2 = sqlSessionFactory.openSession();
UserDao userDao2 = sqlSession2.getMapper(UserDao.class);
User user2 = userDao2.findById(41);
System.out.println(user2);
sqlSession1.close(); System.out.println(user1 == user2);
} }
(1)未开启二级缓存时

Mybatis基于注解开启使用二级缓存

(2)开启二级缓存时

Mybatis基于注解开启使用二级缓存

 
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