在 Mybatis 中集成第三方分布式緩存,可以提高應用程序的性能和可擴展性。以下是在 Mybatis 中集成 Redis 作為分布式緩存的步驟:
在項目的 pom.xml
文件中添加 Redis 客戶端依賴,例如使用 Jedis:
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>3.7.0</version>
</dependency>
在 Mybatis 的配置文件 mybatis-config.xml
中添加 Redis 連接信息:
<configuration>
<!-- ... 其他配置 ... -->
<!-- 添加 Redis 緩存管理器 -->
<settings>
<setting name="cacheEnabled" value="true"/>
<setting name="lazyLoadingEnabled" value="true"/>
<setting name="multipleResultSetsEnabled" value="true"/>
<setting name="useColumnLabel" value="true"/>
<setting name="useGeneratedKeys" value="false"/>
<setting name="autoMappingBehavior" value="PARTIAL"/>
<setting name="defaultExecutorType" value="SIMPLE"/>
<setting name="safeRowBoundsEnabled" value="false"/>
<setting name="mapUnderscoreToCamelCase" value="true"/>
<setting name="localCacheScope" value="SESSION"/>
<setting name="jdbcTypeForNull" value="OTHER"/>
<setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString"/>
</settings>
<!-- 配置 Redis 緩存實現 -->
<cache type="org.mybatis.caches.redis.RedisCache"/>
</configuration>
創建一個 RedisCacheManager
類,用于管理 Redis 連接和緩存操作:
import org.mybatis.cache.Cache;
import org.mybatis.cache.CacheFactory;
import org.mybatis.cache.impl.PerpetualCache;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;
public class RedisCacheManager implements CacheFactory {
private JedisPool jedisPool;
public RedisCacheManager(String host, int port) {
JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
jedisPool = new JedisPool(jedisPoolConfig, host, port);
}
@Override
public Cache getCache(String id) {
return new PerpetualCache(id) {
@Override
public void putObject(Object key, Object value) {
try (Jedis jedis = jedisPool.getResource()) {
jedis.set(key.toString(), value.toString());
}
}
@Override
public Object getObject(Object key) {
try (Jedis jedis = jedisPool.getResource()) {
return jedis.get(key.toString());
}
}
@Override
public void removeObject(Object key) {
try (Jedis jedis = jedisPool.getResource()) {
jedis.del(key.toString());
}
}
@Override
public void clear() {
try (Jedis jedis = jedisPool.getResource()) {
jedis.flushDB();
}
}
@Override
public int getSize() {
try (Jedis jedis = jedisPool.getResource()) {
return jedis.dbSize();
}
}
};
}
public void close() {
if (jedisPool != null) {
jedisPool.close();
}
}
}
在應用程序啟動時,初始化 RedisCacheManager
并將其注冊到 Mybatis:
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import redis.clients.jedis.JedisPoolConfig;
@Configuration
public class MybatisRedisConfig {
@Value("${redis.host}")
private String redisHost;
@Value("${redis.port}")
private int redisPort;
@Bean
public SqlSessionFactoryBean sqlSessionFactory(DataSource dataSource) throws Exception {
SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
sessionFactory.setDataSource(dataSource);
// 初始化 Redis 緩存管理器
RedisCacheManager redisCacheManager = new RedisCacheManager(redisHost, redisPort);
sessionFactory.getConfiguration().setUseCache(true);
sessionFactory.getConfiguration().setCache(redisCacheManager);
return sessionFactory;
}
@Bean
public RedisCacheManager redisCacheManager() {
return new RedisCacheManager(redisHost, redisPort);
}
}
現在,Mybatis 將使用 Redis 作為分布式緩存。你可以在 Mybatis 的映射文件中使用 cache
標簽來啟用緩存:
<select id="selectUserById" resultType="User">
SELECT * FROM users WHERE id = #{id}
<cache/>
</select>
這樣,當你調用 selectUserById
方法時,Mybatis 將首先嘗試從 Redis 緩存中獲取數據,如果沒有找到數據,則從數據庫中查詢并將結果存儲到緩存中。