介绍
使用mybatis时可以使用二级缓存提高查询速度，进而改善用户体验。
使用redis做mybatis的二级缓存可是内存可控<如将单独的服务器部署出来用于二级缓存>，管理方便。
1.在pom.xml文件中引入redis依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> </dependency>
2.在application.properties配置文件中进行redis的配置
## Redis spring.redis.database=0 spring.redis.host=172.16.3.123 spring.redis.port=6379 spring.redis.password= spring.redis.pool.max-active=8 spring.redis.pool.max-wait=-1 spring.redis.pool.max-idle=8 spring.redis.pool.min-idle=0 spring.redis.timeout=0
3.创建cache包，然后创建两个类，一个ApplicationContextHolder实现ApplicationContextAware接口，具体内容如下
package com.ruijie.SpringBootandRedis.cache;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
@Component
public class ApplicationContextHolder implements ApplicationContextAware {
private static ApplicationContext applicationContext;
@Override
public void setApplicationContext(ApplicationContext ctx) throws BeansException {
applicationContext = ctx;
}
/**
* Get application context from everywhere
*
* @return
*/
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
/**
* Get bean by class
*
* @param clazz
* @param <T>
* @return
*/
public static <T> T getBean(Class<T> clazz) {
return applicationContext.getBean(clazz);
}
/**
* Get bean by class name
*
* @param name
* @param <T>
* @return
*/
public static <T> T getBean(String name) {
return (T) applicationContext.getBean(name);
}
}
4.创建RedisCache类实现Cache接口，具体内容如下：
package com.ruijie.SpringBootandRedis.cache;
import org.apache.ibatis.cache.Cache;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
public class RedisCache implements Cache {
private static final Logger logger = LoggerFactory.getLogger(RedisCache.class);
private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
private final String id; // cache instance id
private RedisTemplate redisTemplate;
private static final long EXPIRE_TIME_IN_MINUTES = 30; // redis过期时间
public RedisCache(String id) {
if (id == null) {
throw new IllegalArgumentException("Cache instances require an ID");
}
this.id = id;
}
@Override
public String getId() {
return id;
}
/**
* Put query result to redis
*
* @param key
* @param value
*/
@Override
public void putObject(Object key, Object value) {
try {
RedisTemplate redisTemplate = getRedisTemplate();
ValueOperations opsForValue = redisTemplate.opsForValue();
opsForValue.set(key, value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES);
logger.debug("Put query result to redis");
}
catch (Throwable t) {
logger.error("Redis put failed", t);
}
}
/**
* Get cached query result from redis
*
* @param key
* @return
*/
@Override
public Object getObject(Object key) {
try {
RedisTemplate redisTemplate = getRedisTemplate();
ValueOperations opsForValue = redisTemplate.opsForValue();
logger.debug("Get cached query result from redis");
System.out.println("****"+opsForValue.get(key).toString());
return opsForValue.get(key);
}
catch (Throwable t) {
logger.error("Redis get failed, fail over to db", t);
return null;
}
}
/**
* Remove cached query result from redis
*
* @param key
* @return
*/
@Override
@SuppressWarnings("unchecked")
public Object removeObject(Object key) {
try {
RedisTemplate redisTemplate = getRedisTemplate();
redisTemplate.delete(key);
logger.debug("Remove cached query result from redis");
}
catch (Throwable t) {
logger.error("Redis remove failed", t);
}
return null;
}
/**
* Clears this cache instance
*/
@Override
public void clear() {
RedisTemplate redisTemplate = getRedisTemplate();
redisTemplate.execute((RedisCallback) connection -> {
connection.flushDb();
return null;
});
logger.debug("Clear all the cached query result from redis");
}
/**
* This method is not used
*
* @return
*/
@Override
public int getSize() {
return 0;
}
@Override
public ReadWriteLock getReadWriteLock() {
return readWriteLock;
}
private RedisTemplate getRedisTemplate() {
if (redisTemplate == null) {
redisTemplate = ApplicationContextHolder.getBean("redisTemplate");
}
return redisTemplate;
}
}
5.实体类中要实现Serializable接口，并且要声明序列号
private static final long serialVersionUID = -2566441764189220519L;
6.开启Mybatis的二级缓存
在pom.xml配置文件中配置
mybatis.configuration.cache-enabled=true
在mapper接口中加入
@CacheNamespace(implementation=(com.demo.testdemo.cache.RedisCache.class))
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
