Mybatis如何通过注解开启使用二级缓存

Mybatis如何通过注解开启使用二级缓存

这篇文章主要介绍了Mybatis基于注解开启使用二级缓存,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

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

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

开启缓存 ，为了查看Mybatis中查询的日志，添加 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 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 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&lhtSIoTt;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

（2）开启二级缓存时

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