SSM框架—mybatis使用redis做二级缓存 Spring5（JavaConfig注解配置）

1. 配置环境

Redis 4 安装教程自行google

Spring 5.0.9

Mybatis 3.4.6

2. 依赖

注意：

默认你配置好了SSM的依赖环境，我只说在SSM配好过后怎么把redis加进去
我用的依赖是如下的版本，基本都没有最新jar包的教程，网上的老教程千奇百怪，真的是痛心。
如果你不是用的spring-data-redis的2.X的版本你可以不用看了，看了也没用。

	</properties>
		<jedis.version>2.9.0</jedis.version>
        <redis.version>2.1.0.RELEASE</redis.version>
	</properties>
		<!--Redis支持-->
        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
            <version>${jedis.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-redis</artifactId>
            <version>${redis.version}</version>
        </dependency>

3.配置

首先是redisConfig.java，哇，这个是真的一个巨坑，改动贼多。老教程根本无法使用。作为一个新手瑟瑟发抖。不多说了，先贴代码，再解释


import org.springframework.beans.factory.annotation.Value;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.*;
import org.springframework.data.redis.connection.jedis.JedisClientConfiguration;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.JdkSerializationRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

@Configuration
@PropertySource("classpath:config/redis.properties")
@EnableCaching
public class RedisConfig {
    @Value("${redis.maxTotal}")
    private int maxTotal;

    @Value("${redis.maxIdle}")
    private int maxIdle;

    @Value("${redis.maxWaitMillis}")
    private long maxWaitMillis;

    @Value("${redis.testOnBorrow}")
    private boolean testOnBorrow;

    @Value("${redis.host}")
    private String host;

    @Value("${redis.port}")
    private int port;

    @Value("${redis.timeout}")
    private int timeout;

    @Value("${redis.password}")
    private String password;

    @Value("${redis.database}")
    private int database;

    @Value("${redis.minEvictableIdleTimeMillis}")
    private int minEvictableIdleTimeMillis;

    @Value("${redis.softMinEvictableIdleTimeMillis}")
    private int softMinEvictableIdleTimeMillis;

    @Value("${redis.timeBetweenEvictionRunsMillis}")
    private int timeBetweenEvictionRunsMillis;

    @Value("${redis.numTestsPerEvictionRun}")
    private int numTestsPerEvictionRun;

    @Value("${redis.blockWhenExhausted}")
    private boolean blockWhenExhausted;

    @Value("${redis.testWhileIdle}")
    private boolean testWhileIdle;

    @Bean
    public JedisPoolConfig poolConfig() {
        JedisPoolConfig poolConfig = new JedisPoolConfig();
        poolConfig.setMaxTotal(maxTotal);
        poolConfig.setMaxIdle(maxIdle);
        poolConfig.setMaxWaitMillis(maxWaitMillis);
        poolConfig.setTestOnBorrow(testOnBorrow);
        poolConfig.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        poolConfig.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        poolConfig.setSoftMinEvictableIdleTimeMillis(softMinEvictableIdleTimeMillis);
        poolConfig.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        poolConfig.setNumTestsPerEvictionRun(numTestsPerEvictionRun);
        poolConfig.setBlockWhenExhausted(blockWhenExhausted);
        poolConfig.setTestWhileIdle(testWhileIdle);
        return poolConfig;
    }

    //这个是个巨坑
    @Bean
    public JedisConnectionFactory jedisConnectionFactory(JedisPoolConfig jedisPoolConfig) {
        RedisStandaloneConfiguration configuration = new RedisStandaloneConfiguration();
        configuration.setHostName(host);
        configuration.setPort(port);
        //如果没有密码可以不设置，要注意密码要用RedisPassword类
        configuration.setPassword(RedisPassword.of(password));
        configuration.setDatabase(database);
        //获得默认的连接池构造
        //JedisConnectionFactory对于Standalone模式的没有（RedisStandaloneConfiguration，JedisPoolConfig）的构造函数，
        //所以用JedisClientConfiguration接口的builder方法实例化一个构造器，还得类型转换
        JedisClientConfiguration.JedisPoolingClientConfigurationBuilder jpcf =
                (JedisClientConfiguration.JedisPoolingClientConfigurationBuilder) JedisClientConfiguration.builder();
        //修改我们的连接池配置
        jpcf.poolConfig(jedisPoolConfig);
        //通过构造器来构造jedis客户端配置
        JedisClientConfiguration jedisClientConfiguration = jpcf.build();

        return new JedisConnectionFactory(configuration, jedisClientConfiguration);
    }

    @Bean
    public RedisTemplate redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
		//序列化
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());

        redisTemplate.setValueSerializer(new JdkSerializationRedisSerializer());
        redisTemplate.setHashValueSerializer(new JdkSerializationRedisSerializer());

        return redisTemplate;
    }

    @Bean
    public RedisCacheManager cacheManager(JedisConnectionFactory jedisConnectionFactory) {
        //这里是个坑，老方法已经过时了，用下面方法替代
        return RedisCacheManager.create(jedisConnectionFactory);
    }

}

讲讲那个巨坑JedisConnectionFactory

以前的版本是没有利用RedisStandaloneConfiguration来配置的，我看了几个教程的结果，应该是2.X的版本加进来的。贼难受。
有的教程的JedisConnectionFactory是没有把jedisPoolConfig加进去的。结合几个老教程和Spring boot我个人觉得是应该吧jedisPoolConfig的配置加载进去不然应该不能工作。所以我就找了很多教程，发现其中有个教程就用了现在代码中的方法加了进去
password需要用到RedisPassword.of(password)做下转换

redis.properties配置文件如下

##########################
## redis缓存配置
##########################
# redis主机IP
redis.host=127.0.0.1
# redis端口
redis.port=6379
# 链接超时
redis.timeout=2000
# 密码 如果你没有设置密码 这个配置可以不设置
redis.password=XXXXX
# 指定redis数据库
redis.database=0

##########################
## redis连接池配置
##########################
# 最大连接数
redis.maxTotal=30
# 最大空闲连接数
redis.maxIdle=10
# 获取链接最大等待毫秒
redis.maxWaitMillis=1000
# 获取链接时检查有效性
redis.testOnBorrow=true

# 在空闲时监测有效性
redis.testWhileIdle=true
# 链接耗尽时是否阻塞
redis.blockWhenExhausted=true
# 每次释放链接的最大数目
redis.numTestsPerEvictionRun=1024
# 释放链接的扫描间隔（毫秒）
redis.timeBetweenEvictionRunsMillis=30000
# 最小空闲时间
redis.minEvictableIdleTimeMillis=1800000
# 链接空闲多久后释放
redis.softMinEvictableIdleTimeMillis=10000

在RootConfig.java（根据你的项目来）中加入下列代码，导入RedisConfig.java（我数据库的使用的Druid如果没有分开 Druid是可以不要的）

@Import({DruidDataSourceConfig.class, RedisConfig.class})

随后定义一个RedisCache类实现Cache接口


import org.apache.ibatis.cache.Cache;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.RedisConnection;
import org.springframework.data.redis.connection.jedis.JedisConnection;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.serializer.JdkSerializationRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.stereotype.Component;
import redis.clients.jedis.exceptions.JedisConnectionException;

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

public final class RedisCache implements Cache {
    private static JedisConnectionFactory redisConnectionFactory;
    private final String id;

    public static void setJedisConnectionFactory(JedisConnectionFactory jedisConnectionFactory) {
        RedisCache.redisConnectionFactory = jedisConnectionFactory;
    }
    /**
     * The {@code ReadWriteLock}.
     */
    private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

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

    @Override
    public void clear() {
        RedisConnection connection = null;
        try {
            connection = redisConnectionFactory.getConnection();
            connection.flushDb();
            connection.flushAll();
        } catch (JedisConnectionException e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                connection.close();
            }
        }
    }

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

    @Override
    public Object getObject(Object key) {
        Object result = null;
        RedisConnection connection = null;
        try {
            connection = redisConnectionFactory.getConnection();
            RedisSerializer<Object> serializer = new JdkSerializationRedisSerializer();
            result = serializer.deserialize(connection.get(serializer.serialize(key)));
        } catch (JedisConnectionException e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                connection.close();
            }
        }
        return result;
    }

    @Override
    public ReadWriteLock getReadWriteLock() {
        return this.readWriteLock;
    }

    @Override
    public int getSize() {
        int result = 0;
        RedisConnection connection = null;
        try {
            connection = redisConnectionFactory.getConnection();
            result = Integer.valueOf(connection.dbSize().toString());
        } catch (JedisConnectionException e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                connection.close();
            }
        }
        return result;
    }

    @Override
    public void putObject(Object key, Object value) {
        RedisConnection connection = null;
        try {
            connection = redisConnectionFactory.getConnection();
            RedisSerializer<Object> serializer = new JdkSerializationRedisSerializer();
            connection.set(serializer.serialize(key), serializer.serialize(value));
        } catch (JedisConnectionException e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                connection.close();
            }
        }
    }

    @Override
    public Object removeObject(Object key) {
        RedisConnection connection = null;
        Object result = null;
        try {
            connection = redisConnectionFactory.getConnection();
            RedisSerializer<Object> serializer = new JdkSerializationRedisSerializer();
            result = connection.expire(serializer.serialize(key), 0);
        } catch (JedisConnectionException e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                connection.close();
            }
        }
        return result;
    }

}

用另外一个类注入jedisConnectionFactory

import lombok.Data;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.stereotype.Component;

@Component
public class RedisCacheTransfer {

    @Autowired
    public void setJedisConnectionFactory(JedisConnectionFactory jedisConnectionFactory) {
        RedisCache.setJedisConnectionFactory(jedisConnectionFactory);
    }
}

然后你需要在mybatis中开启cache

<?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>
    <!-- 配置全局属性 -->
    <settings>
        <!--&lt;!&ndash; 使用jdbc的getGeneratedKeys获取数据库自增主键值 &ndash;&gt;-->
        <!--<setting name="useGeneratedKeys" value="true" />-->

        <!--允许cache-->
        <setting name="cacheEnabled" value="true"/>

        <!-- 使用列标签替换列名 默认:true -->
        <setting name="useColumnLabel" value="true"/>

        <!-- 开启驼峰命名转换:Table{create_time} -> Entity{createTime} -->
        <setting name="mapUnderscoreToCamelCase" value="true"/>

        <!-- 打印查询语句 -->
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

</configuration>

这个是我的配置文件，可以不同，根据你的需要来，你只需添加允许cache的那一条就可以了。

另外如果你没有配置文件可在配置数据库中加上

public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource) throws IOException {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setDataSource(dataSource);
        sqlSessionFactoryBean.setConfigLocation(resolver.getResource(CONFIG_LOCATION));
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources(MAPPER_LOCATION));
        sqlSessionFactoryBean.setTypeAliasesPackage("io.ilss.entity");

        return sqlSessionFactoryBean;
    }

当中的resolver是加载配置文件和Mapper的xml文件用的。其中的两个常量（我定义在Constants中）是下面的

/**
 * 数据库相关
 */
public static String CONFIG_LOCATION = "classpath:config/mybatis_config.xml";
public static String MAPPER_LOCATION = "classpath:mappers/*.xml";

最后你只需要在你想用cache的表的Mapper的xml文件的头上加上如下配置就OK了

<mapper namespace="com.example.dao.UserDao">
	<!--缓存设置-->
    <cache type="io.ilss.commons.RedisCache"/>
    .....其他省略，自行配置

如果是用纯dao层注解的，加上相关的cache注解就好了。

接下来，你就可以去测试操作相对应表数据了。

你会看到如下类似日志

Cache Hit Ratio [XXXXXXX.XXXXDao]: 0.3333333333333333

苡仁ilssio

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