首页 / 缓存 / mybatis集成redis作为二级缓存
mybatis集成redis作为二级缓存
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了mybatis集成redis作为二级缓存，小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含6683字，纯文字阅读大概需要10分钟。
内容图文
mybatis默认开启了二级缓存功能，在mybatis主配置文件中，将cacheEnabled设置成false,则会关闭二级缓存功能
<settings>
<!--二级缓存默认开启，false关闭-->
<setting name="cacheEnabled" value="false" />
<!--mybatis日志打印到控制台-->
<setting name="logImpl" value="STDOUT_LOGGING" />
</settings>
mybatis框架虽然默认开启了二级缓存功能，但是并没有默认实现，也就是下面这句代码返回null, 然后走一级缓存
下面是配置Redis作为mybatis的二级缓存，代码如下：
（1）mybatis主配置文件mybatis-config.xml中添加如下配置
<settings>
<!--二级缓存默认开启，false关闭-->
<setting name="cacheEnabled" value="true" />
<!--mybatis日志打印到控制台,以便于观察-->
<setting name="logImpl" value="STDOUT_LOGGING" />
</settings>
（2）FemaleMapper.xml 配置如下
<mapper namespace="qinfeng.zheng.FemaleMapper">
<select id="getFemaleById" resultType="qinfeng.zheng.entity.Female" parameterType="int">
SELECT id,name FROM tb_female where id = #{id};
</select>
<cache eviction="LRU" type="qinfeng.zheng.RedisCache"/>
</mapper>
LRU是mybatis默认的过期策略
（3）qinfeng\zheng\RedisCache.java
import
org.apache.ibatis.cache.Cache;
import
redis.clients.jedis.Jedis;
import
redis.clients.jedis.JedisPool;
import
redis.clients.jedis.JedisPoolConfig;
import
java.io.ByteArrayInputStream;
import
java.io.ByteArrayOutputStream;
import
java.io.ObjectInputStream;
import
java.io.ObjectOutputStream;
import
java.util.Map;
/**
* 使用redis的Hash结构
*/
public
class RedisCache implements Cache {
private String id;
private JedisPool jedisPool;
privatestaticint EXPIRE_TIME = 1000 * 1000;
public RedisCache(String id) {
if (id == null) {
thrownew IllegalArgumentException("Cache instances require an ID");
}
this.id = id;
JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
jedisPool = new JedisPool(jedisPoolConfig, "192.168.79.221", 6379, 3000, "123456");
}
@Override
public String getId() {
return id;
}
@Override
publicvoid putObject(Object key, Object value) {
execute(jedis -> {
try {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
ObjectOutputStream outputStream = new ObjectOutputStream(stream);
outputStream.writeObject(value);
byte[] idBytes = id.getBytes();
jedis.hset(idBytes, key.toString().getBytes(), stream.toByteArray());
// 设置一个过期时间。。if (jedis.ttl(idBytes) == -1) {
jedis.expire(idBytes, EXPIRE_TIME);
}
} catch (Exception e) {
thrownew RuntimeException("put object to redis error!", e);
}
returnnull;
});
}
@Override
public Object getObject(Object key) {
return execute(jedis -> {
try {
byte[] bytes = jedis.hget(id.getBytes(), key.toString().getBytes());
if (bytes == null) {
returnnull;
}
ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes);
ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);
return objectInputStream.readObject();
} catch (Exception e) {
thrownew RuntimeException("get data from redis error!", e);
}
});
}
@Override
public Object removeObject(Object key) {
return execute(jedis -> jedis.hdel(id.getBytes(), key.toString().getBytes()));
}
@Override
publicvoid clear() {
execute(jedis -> jedis.del(id.getBytes())); //因为id是String类型，所以直接jedis.del(id)也行 }
@Override
publicint getSize() {
return (Integer) execute(jedis -> {
Map<byte[], byte[]> map = jedis.hgetAll(id.getBytes());
return map.size();
});
}
private Object execute(RedisCallBack redisCallBack) {
try (Jedis jedis = jedisPool.getResource()) {
return redisCallBack.callBack(jedis);
} catch (Exception e) {
thrownew RuntimeException(e.getMessage());
}
}
}
public
interface
RedisCallBack {
Object callBack(Jedis jedis);
}
使用redis作为mybatis的二级缓存框架，最主要就是实现mybatis提供的spi接口--Cache即可，然后实现putObject,getObject这两个主要的方法即可。
除此之外，记得pom.xml文件中添加jedis依赖
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.9.0</version>
</dependency>
（4）修改测试代码
public
class
V1Test {
public
static
void
main(String[] args) {
try (InputStream is = Resources.getResourceAsStream("mybatis-config.xml")) {
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
FemaleMapper femaleMapper = sqlSession.getMapper(FemaleMapper.class);
Female female = femaleMapper.getFemaleById(1);
System.out.println(female);
System.out.println("-----------分隔符----------------------------------");
SqlSession sqlSession2 = sqlSessionFactory.openSession(true);
FemaleMapper femaleMapper2 = sqlSession2.getMapper(FemaleMapper.class);
Female female2 = femaleMapper2.getFemaleById(1);
System.out.println(female2);
} catch (Exception e) {
e.printStackTrace();
}
}
}
第一次运行：
Opening JDBC Connection
Created connection 331510866.
==> Preparing: SELECT id,name FROM tb_female where id = ?;
==> Parameters: 1(Integer)
<== Columns: id, name
<== Row: 1, soga
<== Total: 1
Female(id=1, name=soga)
-----------分隔符----------------------------------
Opening JDBC Connection
Created connection 1316061703.
==> Preparing: SELECT id,name FROM tb_female where id = ?;
==> Parameters: 1(Integer)
<== Columns: id, name
<== Row: 1, soga
<== Total: 1
Female(id=1, name=soga)
哈哈，貌似还是查库两次，redis缓存好像没有起到作用。
事实上，mybatis框架为二级缓存提供了一个缓冲Map, 需要在调用commit方法之后，才会将缓冲区Map中的数据写入到redis中。
我们修改一下测试代码，然后再运行观察结果
public
class
V1Test {
public
static
void
main(String[] args) {
try (InputStream is = Resources.getResourceAsStream("mybatis-config.xml")) {
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
FemaleMapper femaleMapper = sqlSession.getMapper(FemaleMapper.class);
Female female = femaleMapper.getFemaleById(1);
System.out.println(female);
sqlSession.commit();
System.out.println("-----------分隔符----------------------------------");
SqlSession sqlSession2 = sqlSessionFactory.openSession(true);
FemaleMapper femaleMapper2 = sqlSession2.getMapper(FemaleMapper.class);
Female female2 = femaleMapper2.getFemaleById(1);
System.out.println(female2);
} catch (Exception e) {
e.printStackTrace();
}
}
}
运行结果：
哎哎哎，报了个错，记得Female 需要序列化
Opening JDBC Connection
Created connection 490150701.
==> Preparing: SELECT id,name FROM tb_female where id = ?;
==> Parameters: 1(Integer)
<== Columns: id, name
<== Row: 1, soga
<== Total: 1
Female(id=1, name=soga)
-----------分隔符----------------------------------
Cache Hit Ratio [qinfeng.zheng.FemaleMapper]: 0.5
Female(id=1, name=soga)
请看，这次只查了一个库，第2冲直接缓存命中、
我们再运行一次刚才的代码
Cache Hit Ratio [qinfeng.zheng.FemaleMapper]: 1.0 Female(id=1, name=soga) -----------分隔符---------------------------------- Cache Hit Ratio [qinfeng.zheng.FemaleMapper]: 1.0 Female(id=1, name=soga)
两次都缓存命中！！
再看一下redis:
好了， mybatis整合redis为二级缓存到此完毕，下章分析一下它的源码实现！
原文：https://www.cnblogs.com/z-qinfeng/p/11920606.html
内容总结
以上是互联网集市为您收集整理的mybatis集成redis作为二级缓存全部内容，希望文章能够帮你解决mybatis集成redis作为二级缓存所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错，欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 gblab@vip.qq.com 举报，一经查实，本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。
来源：【匿名】