Redis缓存

redis作为key-value型的存储系统，尤其是其支持的value类型更多，使用者可以选择redis作数据库，也可作为缓存实现。这里，简单的介绍下使用redis作为缓存实现（以RedisTemplate操作字符串为例）

1、pom.xml中添加依赖

<!-- redis -->

<dependency>

    <groupId>org.springframework.data</groupId>

    <artifactId>spring-data-redis</artifactId>

    <version>1.1.1.RELEASE</version>

    <exclusions>

        <exclusion>

            <artifactId>jcl-over-slf4j</artifactId>

            <groupId>org.slf4j</groupId>

        </exclusion>

    </exclusions>

</dependency>

<dependency>

    <groupId>redis.clients</groupId>

    <artifactId>jedis</artifactId>

    <version>2.1.0</version>

</dependency>

2、编写redis配置文件 spring-redis.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans";;

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";;

       xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-4.0.xsd"

       default-lazy-init="true">

    <description>redis配置</description>

    <!-- Jedis 连接池配置 -->

    <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">

        <property name="maxActive" value="1000"/>

        <property name="maxIdle" value="100"/>

        <property name="maxWait" value="90000"/>

        <property name="testOnBorrow" value="true"/>

    </bean>

    <!-- Jedis ConnectionFactory 数据库连接配置 -->

    <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">

        <property name="hostName" value="masterredis.simonsfan.cn"/>

        <property name="port" value="6426"/>

        <property name="password" value=""/>

        <property name="poolConfig" ref="jedisPoolConfig"/>

    </bean>

    <!-- jedisTemplate 配置 -->

    <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate">

        <property name="connectionFactory" ref="jedisConnectionFactory"></property>

        <property name="keySerializer">

            <bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/>

        </property>

        <property name="hashKeySerializer">

            <bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/>

        </property>

        <property name="valueSerializer">

            <bean class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer"/>

        </property>

        <property name="hashValueSerializer">

            <bean class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer"/>

        </property>

    </bean>

</beans>

3、导入spring主配置文件

<import resource="classpath:spring-redis.xml" />

4、编写测试类

@Controller

public class UserController {

    @Autowired

    private UserActivityInfoMapper userActivityInfoMapper;

    @Resource

    private RedisTemplate<String, String> redisTemplate;

    @ResponseBody

    @RequestMapping(value = "/activity", produces = "application/json;charset=utf-8")

    public String selectByPrimaryKey(@RequestParam(required = false) int id) {

        String value = null;

        String redisKey = "test_redis_key";

        value = redisTemplate.opsForValue().get(redisKey);

        if (value != null) {

            return value;

        }

        value = userActivityInfoMapper.selectByPrimaryKey(id).getActName();

        if (value != null) {

            redisTemplate.opsForValue().set(redisKey, value);

        }

        return value;

    }

}

有时情况下需要指定缓存时间

redisTemplate.opsForValue().set(redisKey, value, 1800, TimeUnit.SECONDS)或

redisTemplate.expire(redisKey, 1800 , TimeUnit.SECONDS)

表示缓存有效期为1800s

5、测试：浏览器多次访问该接口，端点调试，发现第二次访问开始，value值是从redis缓存中获取的

也可以来通过如下方法设置缓存时间

redisTemplate.opsForValue().set(redisKey, value, 1800, TimeUnit.SECONDS)

操作value为字符串类型的常用方法

6、RedisTemplate用来操作不同value类型的方法：

redisTemplate.opsForValue();   //操作字符串

redisTemplate.opsForHash();    //操作hash

redisTemplate.opsForList();      //操作list

redisTemplate.opsForSet();      //操作set

redisTemplate.opsForZSet();    //操作有序set0