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mybatis+redis实现二级缓存
在网上看了很多资料，发现例子都是千篇一律的相互复制。而且，使用的都是jedis的客户端。。我这里使用的是redistemplate类实现。
缓存的原理。。实现cache类接口，当哪个类需要缓存的时候，就直接将cache标签引入，并且制定我们的缓存类就可以了。
上代码：
1、引入spring-data-redis
1 <!-- redis服务 start-->2 <dependency>3 <groupId>org.springframework.data</groupId>4 <artifactId>spring-data-redis</artifactId>5 <version>1.6.2.RELEASE</version>6 </dependency>
2、java缓存类，至于里面如何获取bean，ApplicationUtil.getBean("redisTemplate")，请查看我上篇文章：普通java类获取springbean的方法
1 package com.iafclub.demo.cache; 2 3 import java.io.Serializable; 4 import java.util.Set; 5 import java.util.concurrent.TimeUnit; 6 import java.util.concurrent.locks.ReadWriteLock; 7 import java.util.concurrent.locks.ReentrantReadWriteLock; 8 9 import org.apache.commons.codec.digest.DigestUtils; 10 import org.apache.ibatis.cache.Cache; 11 import org.apache.log4j.Logger; 12 import org.springframework.dao.DataAccessException; 13 import org.springframework.data.redis.connection.RedisConnection; 14 import org.springframework.data.redis.core.RedisCallback; 15 import org.springframework.data.redis.core.RedisTemplate; 16 import org.springframework.data.redis.serializer.JdkSerializationRedisSerializer; 17 18 import com.iafclub.demo.util.ApplicationUtil; 19 20 /** 21 * 使用第三方缓存服务器，处理二级缓存 22 * 缓存时间在putObject中设置 23 * 24 * @author chenweixian 25 * 26 */ 27 public class RedisCache implements Cache { 28 private static final Logger logger = Logger.getLogger(RedisCache.class); 29 30 private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock(true); 31 32 private final String COMMON_CACHE_KEY = "demo:MYBATIS:"; 33 34 private String id; 35 36 private JdkSerializationRedisSerializer jdkSerializer = new JdkSerializationRedisSerializer(); 37 /**所有key*/ 38 private String getKeys() { 39 return COMMON_CACHE_KEY + this.id + ":*"; 40 } 41 /** 42 * 按照一定规则标识key 43 */ 44 private String getKey(Object key) { 45 return COMMON_CACHE_KEY + this.id + ":"+DigestUtils.md5Hex(String.valueOf(key)); 46 } 47 48 public RedisTemplate<String, Serializable> getRedisTemplate(){ 49 return (RedisTemplate<String, Serializable>) ApplicationUtil.getBean("redisTemplate"); 50 } 51 52 public RedisCache(final String id) { 53 if (id == null) { 54 throw new IllegalArgumentException("必须传入ID"); 55 } 56 logger.debug("MybatisRedisCache:id=" + id); 57 this.id = id; 58 } 59 60 @Override 61 public String getId() { 62 return this.id; 63 } 64 65 @Override 66 public void putObject(Object key, Object value) { 67 if (getRedisTemplate()==null){ 68 return ; 69 } 70 if (value != null) { 71 getRedisTemplate().opsForValue().set(getKey(key), 72 jdkSerializer.serialize(value), 20, TimeUnit.SECONDS); 73 } 74 } 75 76 @Override 77 public Object getObject(Object key) { 78 if (getRedisTemplate()==null){ 79 return null; 80 } 81 try { 82 if (key != null) { 83 Object obj = getRedisTemplate().opsForValue().get(getKey(key)); 84 return jdkSerializer.deserialize((byte[]) obj); 85 } 86 } catch (Exception e) { 87 logger.error("redis "); 88 } 89 return null; 90 } 91 92 @Override 93 public Object removeObject(Object key) { 94 if (getRedisTemplate()==null){ 95 return null; 96 } 97 try { 98 if (key != null) { 99 getRedisTemplate().delete(getKey(key));100 logger.debug("从缓存中移除-----"+this.id);101 }102 } catch (Exception e) {103 }104 return null;105 }106 107 @Override108 public void clear() {109 if (getRedisTemplate()==null){110 return ;111 }112 try {113 Set<String> keys = getRedisTemplate().keys(getKeys());114 getRedisTemplate().delete(keys);115 logger.debug("出现新增、修改、删除操作，清空对应Mapper缓存======>"+keys.size());116 } catch (Exception e) {117 logger.error(e.getMessage(), e);118 }119 }120 121 @Override122 public int getSize() {123 if (getRedisTemplate()==null){124 return 0;125 }126 Long size = getRedisTemplate().execute(127 new RedisCallback<Long>() {128 @Override129 public Long doInRedis(RedisConnection connection)130 throws DataAccessException {131 return connection.dbSize();132 }133 });134 return size.intValue();135 }136 137 @Override138 public ReadWriteLock getReadWriteLock() {139 return this.readWriteLock;140 }141 }
3、mybatis配置：注意加粗标红，斜线部分:
21 <!-- redis缓存 -->22 <cache type="com.iafclub.demo.cache.RedisCache" eviction="LRU" />
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" > 3 <mapper namespace="com.iafclub.demo.dao.DictionaryMapper" > 4 <resultMap id="BaseResultMap" type="com.iafclub.demo.domain.Dictionary" > 5 <id column="auto_id" property="autoId" jdbcType="VARCHAR" /> 6 <result column="type_id" property="typeId" jdbcType="VARCHAR" /> 7 <result column="type_name" property="typeName" jdbcType="VARCHAR" /> 8 <result column="field_key" property="fieldKey" jdbcType="VARCHAR" /> 9 <result column="field_value" property="fieldValue" jdbcType="VARCHAR" />10 <result column="field_back" property="fieldBack" jdbcType="VARCHAR" />11 <result column="field_back2" property="fieldBack2" jdbcType="VARCHAR" />12 <result column="field_back3" property="fieldBack3" jdbcType="VARCHAR" />13 <result column="remark" property="remark" jdbcType="VARCHAR" />14 <result column="editor" property="editor" jdbcType="VARCHAR" />15 <result column="edittime" property="edittime" jdbcType="TIMESTAMP" />16 </resultMap>17 <sql id="Base_Column_List" >18 auto_id, type_id, type_name, field_key, field_value, field_back, field_back2, field_back3, 19 remark, editor, edittime20 </sql> 21 <!-- redis缓存 -->22 <cache type="com.iafclub.demo.cache.RedisCache" eviction="LRU" />23 <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.String" >24 select 25 <include refid="Base_Column_List" />26 from t_dictionary27 where auto_id = #{autoId}28 </select>29 <select id="selectAll" resultMap="BaseResultMap" parameterType="java.lang.String" >30 select 31 <include refid="Base_Column_List" />32 from t_dictionary limit 20033 </select>34 </mapper>
4、mybatis配置：
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> 3 <configuration> 4 <settings> 5 <!-- 开启缓存 --> 6 <setting name="cacheEnabled" value="true"/> 7 <!-- Java属性与数据库字段采用驼峰式对应 --> 8 <setting name="mapUnderscoreToCamelCase" value="true" /> 9 </settings>10 <!-- 11 <settings> 12 <setting name="useColumnLabel" value="http://www.mamicode.com/true"/> 13 <setting name="useGeneratedKeys" value="http://www.mamicode.com/false"/> 14 <setting name="cacheEnabled" value="http://www.mamicode.com/true" /> 这个配置使全局的映射器启用或禁用缓存15 <setting name="multipleResultSetsEnabled" value="http://www.mamicode.com/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16 <setting name="defaultExecutorType" value="http://www.mamicode.com/REUSE" />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17 <setting name="lazyLoadingEnabled" value="http://www.mamicode.com/false" />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18 <setting name="aggressiveLazyLoading" value="http://www.mamicode.com/true" />19 <setting name="enhancementEnabled" value="http://www.mamicode.com/true"/>20 <setting name="defaultStatementTimeout" value="http://www.mamicode.com/25000" /> 设置超时时间，它决定驱动等待一个数据库响应的时间。21 </settings> 22 -->23 </configuration>
5、其他页面实现，次要。。。
n、测试运行结果：只有第一次查询，发送了sql，第二次后，就不会发送sql，直接在redis中查询。如果进行增删改，都会清空，然后，再发sql
mybatis+redis实现二级缓存
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