redis学习总结-redis作为MyBatis的自定义缓存

1、RedisCache.java

package com.houtai.cache;

import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

import org.apache.ibatis.cache.Cache;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

public class RedisCache implements Cache {
private static Log logger = LogFactory.getLog(RedisCache.class);
private Jedis redisClient = createClient();
/** The ReadWriteLock. */
private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

private String id;

public RedisCache(final String id) {
if (id == null) {
throw new IllegalArgumentException("Cache instances require an ID");
}
logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>MybatisRedisCache:id=" + id);
this.id = id;
}

public String getId() {
return this.id;
}

public int getSize() {
return Integer.valueOf(redisClient.dbSize().toString());
}

public void putObject(Object key, Object value) {
logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>putObject:" + key + "=" + value);
redisClient.set(SerializeUtil.serialize(key.toString()), SerializeUtil
.serialize(value));
}

public Object getObject(Object key) {
Object value = SerializeUtil.unserialize(redisClient.get(SerializeUtil
.serialize(key.toString())));
logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>getObject:" + key + "=" + value);
return value;
}

public Object removeObject(Object key) {
return redisClient.expire(SerializeUtil.serialize(key.toString()), 0);
}

public void clear() {
redisClient.flushDB();
}

public ReadWriteLock getReadWriteLock() {
return readWriteLock;
}

protected static Jedis createClient() {
try {
JedisPool pool = new JedisPool(new JedisPoolConfig(),
"localhost");
return pool.getResource();
} catch (Exception e) {
e.printStackTrace();
}
throw new RuntimeException("初始化连接池错误");
}

}

2、序列化与方序列化工具类

package com.houtai.cache;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/**
*
* @author 作者： wcy
* @version 创建时间：Mar 20, 2015 3:27:39 PM
* @Description: TODO(用于序列化键值对)
*/
public class SerializeUtil {

public static byte[] serialize(Object object) {
ObjectOutputStream oos = null;
ByteArrayOutputStream baos = null;
try {
// 序列化
baos = new ByteArrayOutputStream();
oos = new ObjectOutputStream(baos);
oos.writeObject(object);
byte[] bytes = baos.toByteArray();
return bytes;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

public static Object unserialize(byte[] bytes) {
if (bytes == null)
return null;
ByteArrayInputStream bais = null;
try {
// 反序列化
bais = new ByteArrayInputStream(bytes);
ObjectInputStream ois = new ObjectInputStream(bais);
return ois.readObject();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}

3、自定义缓存的入口，继承MyBatis的loggingCache类

package com.houtai.cache;

import org.apache.ibatis.cache.decorators.LoggingCache;

public class LoggingRedisCache extends LoggingCache{

public LoggingRedisCache(String id) {
super(new RedisCache(id));
// TODO Auto-generated constructor stub
}

}

4、同时配置MyBatis的配置文件

<?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>
<!-- 这个配置使全局的映射器启用或禁用缓存 -->
<setting name="cacheEnabled" value="true" />
<!-- 对于未知的SQL查询，允许返回不同的结果集以达到通用的效果 -->
<setting name="multipleResultSetsEnabled" value="true" />
<!-- 配置默认的执行器。SIMPLE 执行器没有什么特别之处。REUSE 执行器重用预处理语句。BATCH 执行器重用语句和批量更新 -->
<setting name="defaultExecutorType" value="REUSE" />
<!-- 全局启用或禁用延迟加载。当禁用时，所有关联对象都会即时加载。 -->
<setting name="lazyLoadingEnabled" value="false" />
<setting name="aggressiveLazyLoading" value="true" />
<!-- <setting name="enhancementEnabled" value="true"/> -->
<!-- 设置超时时间，它决定驱动等待一个数据库响应的时间。 -->
<setting name="defaultStatementTimeout" value="25000" />
</settings>
<typeAliases>
<package name="com.houtai.model" />
</typeAliases>

<mappers>
<mapper resource="sqlmap/houtai/accountMapper.xml" />
<mapper resource="sqlmap/houtai/categoryMapper.xml" />
<mapper resource="sqlmap/houtai/goodsMapper.xml" />
<mapper resource="sqlmap/houtai/sorderMapper.xml" />
<mapper resource="sqlmap/houtai/forderMapper.xml" />
</mappers>
</configuration>

5、因为使用MyBatis的二级缓存，所以要缓存的类，必须开启<cache/>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE  mapper  PUBLIC  "-//mybatis.org//DTD  Mapper  3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.houtai.model.Account">
<!-- redis缓存 -->
<cache eviction="LRU" type="com.houtai.cache.LoggingRedisCache"/>

<select id="loginAccount" parameterType="account" resultType="account" useCache="true">
select * from account a where a.login=#{login} and a.pass=#{pass}
</select>
</mapper>

6、最后测试通过。