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。