【SSM】整合Redis
前言
服务端缓存的意义大多数在于减轻数据库压力,提供响应速度,而缺点也是显而易见的,会带来缓存与数据库一致性问题。当然,Redis还可以作为分布式锁。
Redis
想在项目中使用Redis需要做的事情不多,改动图中几个文件
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@Service public class DeptServiceImpl implements DeptService { @Autowired DeptDOMapper deptDOMapper; @Autowired private RedisTemplate redisTemplate; @Override public List<DeptInfo> listDeptInfo(String name) { List<DeptInfo> object = (List<DeptInfo>) redisTemplate.opsForValue().get(name); if (object != null) { return object; }else { List<DeptDO> deptDOList = deptDOMapper.listDept(name); List<DeptInfo> deptInfos = new ArrayList<>(); deptDOList.stream().forEach(x -> { DeptInfo info = new DeptInfo(); info.setName(x.getName()); info.setId(x.getId()); deptInfos.add(info); }); redisTemplate.opsForValue().set(name,deptInfos); return deptInfos; } } }
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redis.host=127.0.0.1 redis.port=6379 redis.maxIdle=400 redis.maxTotal=6000 redis.maxWaitMillis=1000 redis.blockWhenExhausted=true redis.testOnBorrow=true redis.timeout=10000
applicationContext.xml导入配置
<import resource="spring-redis.xml"></import>
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <!-- 加载配置文件 --> <context:property-placeholder location="classpath:redis.properties" /> <!-- redis数据源 --> <bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig"> <!-- 最大空闲数 --> <property name="maxIdle" value="${redis.maxIdle}" /> <!-- 最大空连接数 --> <property name="maxTotal" value="${redis.maxTotal}" /> <!-- 最大等待时间 --> <property name="maxWaitMillis" value="${redis.maxWaitMillis}" /> <!-- 连接超时时是否阻塞,false时报异常,ture阻塞直到超时, 默认true --> <property name="blockWhenExhausted" value="${redis.blockWhenExhausted}" /> <!-- 返回连接时,检测连接是否成功 --> <property name="testOnBorrow" value="${redis.testOnBorrow}" /> </bean> <!-- Spring-redis连接池管理工厂 --> <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"> <!-- IP地址 --> <property name="hostName" value="${redis.host}" /> <!-- 端口号 --> <property name="port" value="${redis.port}" /> <!-- 超时时间 默认2000--> <property name="timeout" value="${redis.timeout}" /> <!-- 连接池配置引用 --> <property name="poolConfig" ref="poolConfig" /> <!-- usePool:是否使用连接池 --> <property name="usePool" value="true"/> </bean> <!-- redis template definition --> <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"> <property name="connectionFactory" ref="jedisConnectionFactory" /> <property name="keySerializer"> <bean class="org.springframework.data.redis.serializer.StringRedisSerializer" /> </property> <property name="valueSerializer"> <bean class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer" /> </property> <property name="hashKeySerializer"> <bean class="org.springframework.data.redis.serializer.StringRedisSerializer" /> </property> <property name="hashValueSerializer"> <bean class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer" /> </property> <!--开启事务 --> <property name="enableTransactionSupport" value="true"></property> </bean> </beans>
pom.xml引入jar包,jedis包的版本要注意一下,过高可能不兼容,启动时抛错
<!-- https://mvnrepository.com/artifact/redis.clients/jedis --> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.9.1</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-redis --> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-redis</artifactId> <version>2.1.6.RELEASE</version> </dependency>
缓存几个问题
1.缓存雪崩
加上一个随机过期时间
2.缓存穿透
布隆过滤器
缓存空数据,设置短过期时间
小结
缓存这方面的知识点非常多,这里只是做一个接入的记录。