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     @Override
108     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     @Override
122     public int getSize() {
123         if (getRedisTemplate()==null){
124             return 0;
125         }
126         Long size = getRedisTemplate().execute(
127                 new RedisCallback<Long>() {
128                     @Override
129                     public Long doInRedis(RedisConnection connection)
130                             throws DataAccessException {
131                         return connection.dbSize();
132                     }
133                 });
134         return size.intValue();
135     }
136 
137     @Override
138     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, edittime
20   </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_dictionary
27     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 200
33   </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="true"/>     
13         <setting name="useGeneratedKeys" value="false"/>     
14         <setting name="cacheEnabled" value="true" /> 这个配置使全局的映射器启用或禁用缓存
15         <setting name="multipleResultSetsEnabled" 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
16         <setting name="defaultExecutorType" value="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="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="true" />
19         <setting name="enhancementEnabled" value="true"/>
20         <setting name="defaultStatementTimeout" value="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

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原文地址：https://www.cnblogs.com/a393060727/p/6110723.html