一,Redis与ssm整合
1.1 pom.xml配置
在pom.xml中配置相关的redis文件
redis文件:
XML
<redis.version>2.9.0</redis.version>
<redis.spring.version>1.7.1.RELEASE</redis.spring.version>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>${redis.version}</version>
</dependency>
整个pom.xml文件:
XML
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>ssm2</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>ssm2 Maven Webapp</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<maven.compiler.plugin.version>3.7.0</maven.compiler.plugin.version>
<!--添加jar包依赖-->
<!--1.spring 5.0.2.RELEASE相关-->
<spring.version>5.0.2.RELEASE</spring.version>
<!--2.mybatis相关-->
<mybatis.version>3.4.5</mybatis.version>
<!--mysql-->
<mysql.version>5.1.44</mysql.version>
<!--pagehelper分页jar依赖-->
<pagehelper.version>5.1.2</pagehelper.version>
<!--mybatis与spring集成jar依赖-->
<mybatis.spring.version>1.3.1</mybatis.spring.version>
<!--3.dbcp2连接池相关 druid-->
<commons.dbcp2.version>2.1.1</commons.dbcp2.version>
<commons.pool2.version>2.4.3</commons.pool2.version>
<!--4.log日志相关-->
<log4j2.version>2.9.1</log4j2.version>
<!--5.其他-->
<junit.version>4.12</junit.version>
<servlet.version>4.0.0</servlet.version>
<lombok.version>1.18.2</lombok.version>
<ehcache.version>2.10.0</ehcache.version>
<slf4j-api.version>1.7.7</slf4j-api.version>
<redis.version>2.9.0</redis.version>
<redis.spring.version>1.7.1.RELEASE</redis.spring.version>
</properties>
<dependencies>
<!--1.spring相关-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!--2.mybatis相关-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<!--mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<!--pagehelper分页插件jar包依赖-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>${pagehelper.version}</version>
</dependency>
<!--mybatis与spring集成jar包依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>${mybatis.spring.version}</version>
</dependency>
<!--3.dbcp2连接池相关-->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-dbcp2</artifactId>
<version>${commons.dbcp2.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-pool2</artifactId>
<version>${commons.pool2.version}</version>
</dependency>
<!--4.log日志相关依赖-->
<!--核心log4j2jar包-->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>${log4j2.version}</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>${log4j2.version}</version>
</dependency>
<!--web工程需要包含log4j-web,非web工程不需要-->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-web</artifactId>
<version>${log4j2.version}</version>
</dependency>
<!--5.其他-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>${servlet.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- jsp依赖-->
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.3</version>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.3</version>
</dependency>
<!-- 做服务端参数校验 JSR303 的jar包依赖 -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>6.0.7.Final</version>
</dependency>
<!-- 用来SpringMVC支持json数据转换-->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.3</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.3</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.3</version>
</dependency>
<!-- shiro相关依赖 -->
<dependency>
<groupId>org.apache.shiro</groupId>
<artifactId>shiro-core</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>org.apache.shiro</groupId>
<artifactId>shiro-web</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>org.apache.shiro</groupId>
<artifactId>shiro-spring</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>net.sf.ehcache</groupId>
<artifactId>ehcache</artifactId>
<version>${ehcache.version}</version>
</dependency>
<!-- slf4j核心包 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j-api.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>${slf4j-api.version}</version>
<scope>runtime</scope>
</dependency>
<!--用于与slf4j保持桥接 -->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>${log4j2.version}</version>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>${redis.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-redis</artifactId>
<version>${redis.spring.version}</version>
</dependency>
</dependencies>
<build>
<finalName>ssm2</finalName>
<resources>
<!--解决mybatis-generator-maven-plugin运行时没有将XxxMapper.xml文件放入target文件夹的问题-->
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
<!--解决mybatis-generator-maven-plugin运行时没有将jdbc.properites文件放入target文件夹的问题-->
<resource>
<directory>src/main/resources</directory>
<includes>
<include>*.properties</include>
<include>*.xml</include>
</includes>
</resource>
</resources>
<pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven.compiler.plugin.version}</version>
<configuration>
<source>${maven.compiler.source}</source>
<target>${maven.compiler.target}</target>
<encoding>${project.build.sourceEncoding}</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<dependencies>
<!--使用Mybatis-generator插件不能使用太高版本的mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
</dependencies>
<configuration>
<overwrite>true</overwrite>
</configuration>
</plugin>
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.1.0</version>
</plugin>
<!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.1</version>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.2</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>
1.2 spring-redis.xml配置
这个配置文件的作用主要用于配置数据源和连接工厂还有配置序列化的用途
步骤:
① 注册redis.properties
② 配置数据源[连接]
③ 连接工厂
④ 配置序列化器
⑤ 配置redis的key生成策略
具体步骤看下代码:
spring-redis.xml:
java
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:cache="http://www.springframework.org/schema/cache"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/cache
http://www.springframework.org/schema/cache/spring-cache.xsd">
<!-- 1. 引入properties配置文件 -->
<context:property-placeholder location="classpath:redis.properties" />
<!-- 2. redis连接池配置-->
<bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig">
<!--最大空闲数-->
<property name="maxIdle" value="300"/>
<!--连接池的最大数据库连接数 -->
<property name="maxTotal" value="${redis.maxTotal}"/>
<!--最大建立连接等待时间-->
<property name="maxWaitMillis" value="${redis.maxWaitMillis}"/>
<!--逐出连接的最小空闲时间 默认1800000毫秒(30分钟)-->
<property name="minEvictableIdleTimeMillis" value="${redis.minEvictableIdleTimeMillis}"/>
<!--每次逐出检查时 逐出的最大数目 如果为负数就是 : 1/abs(n), 默认3-->
<property name="numTestsPerEvictionRun" value="${redis.numTestsPerEvictionRun}"/>
<!--逐出扫描的时间间隔(毫秒) 如果为负数,则不运行逐出线程, 默认-1-->
<property name="timeBetweenEvictionRunsMillis" value="${redis.timeBetweenEvictionRunsMillis}"/>
<!--是否在从池中取出连接前进行检验,如果检验失败,则从池中去除连接并尝试取出另一个-->
<property name="testOnBorrow" value="${redis.testOnBorrow}"/>
<!--在空闲时检查有效性, 默认false -->
<property name="testWhileIdle" value="${redis.testWhileIdle}"/>
</bean>
<!-- 3. redis连接工厂 -->
<bean id="connectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
destroy-method="destroy">
<property name="poolConfig" ref="poolConfig"/>
<!--IP地址 -->
<property name="hostName" value="${redis.hostName}"/>
<!--端口号 -->
<property name="port" value="${redis.port}"/>
<!--如果Redis设置有密码 -->
<property name="password" value="${redis.password}"/>
<!--客户端超时时间单位是毫秒 -->
<property name="timeout" value="${redis.timeout}"/>
</bean>
<!-- 4. redis操作模板,使用该对象可以操作redis
hibernate课程中hibernatetemplete,相当于session,专门操作数据库。
-->
<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate">
<property name="connectionFactory" ref="connectionFactory"/>
<!--如果不配置Serializer,那么存储的时候缺省使用String,如果用User类型存储,那么会提示错误User can't cast to String!! -->
<property name="keySerializer">
<bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/>
</property>
<property name="valueSerializer">
<bean class="org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer"/>
</property>
<property name="hashKeySerializer">
<bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/>
</property>
<property name="hashValueSerializer">
<bean class="org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer"/>
</property>
<!--开启事务 -->
<property name="enableTransactionSupport" value="true"/>
</bean>
<!-- 5.配置缓存管理器 -->
<bean id="redisCacheManager" class="org.springframework.data.redis.cache.RedisCacheManager">
<constructor-arg name="redisOperations" ref="redisTemplate"/>
<!--redis缓存数据过期时间单位秒-->
<property name="defaultExpiration" value="${redis.expiration}"/>
<!--是否使用缓存前缀,与cachePrefix相关-->
<property name="usePrefix" value="true"/>
<!--配置缓存前缀名称-->
<property name="cachePrefix">
<bean class="org.springframework.data.redis.cache.DefaultRedisCachePrefix">
<constructor-arg index="0" value="-cache-"/>
</bean>
</property>
</bean>
<!--6.配置缓存生成键名的生成规则-->
<bean id="cacheKeyGenerator" class="com.zking.ssm.redis.CacheKeyGenerator"></bean>
<!--7.启用缓存注解功能-->
<cache:annotation-driven cache-manager="redisCacheManager" key-generator="cacheKeyGenerator"/>
</beans>
redis.properties:
java
redis.hostName=localhost
redis.port=6379
redis.password=123456
redis.timeout=10000
redis.maxIdle=300
redis.maxTotal=1000
redis.maxWaitMillis=1000
redis.minEvictableIdleTimeMillis=300000
redis.numTestsPerEvictionRun=1024
redis.timeBetweenEvictionRunsMillis=30000
redis.testOnBorrow=true
redis.testWhileIdle=true
redis.expiration=3600
1.3 spring上下文配置
applicationContext.xml:
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"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<!--1. 引入外部多文件方式 -->
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
<property name="ignoreResourceNotFound" value="true" />
<property name="locations">
<list>
<value>classpath:jdbc.properties</value>
<value>classpath:redis.properties</value>
</list>
</property>
</bean>
<!-- 随着后续学习,框架会越学越多,不能将所有的框架配置,放到同一个配制间,否者不便于管理 -->
<import resource="applicationContext-mybatis.xml"></import>
<import resource="spring-redis.xml"></import>
<import resource="applicationContext-shiro.xml"></import>
</beans>
二,Redis注解式
① @Cacheable (可读取与写入)
@Cacheable是Spring框架提供的一个缓存注解,用于标记方法的返回结果可以被缓存起来,以提高系统的性能。
如下:
测试代码:
classBiz:
@Cacheable("clz") Clazz selectByPrimaryKey(Integer cid);
测试类text:
java@Test public void test1(){ System.out.println(clazzBiz.selectByPrimaryKey(1)); System.out.println(clazzBiz.selectByPrimaryKey(1)); }
运行结果,只会走一次数据库,之后都是走redis缓存,减少了数据库压力
数据库:
value:缓存位置的一段名称,不能为空
key:缓存的key,默认为空,表示使用方法的参数类型及参数值作为key,支持SpEL
condition:触发条件,满足条件就加入缓存,默认为空,表示全部都加入缓存,支持SpEL
② CachePut(只读数据)
@CachePut
注解用于更新缓存中的内容。 当使用注解标记的方法被调用时,Spring会更新缓存中的值,而不管缓存中是否已经存在相应的键值对,如下classBiz:
java@CachePut(value = "xx",key = "'cid:'+#cid") Clazz selectByPrimaryKey(Integer cid);
测试类text:
value:缓存的名称,在 spring 配置文件中定义,必须指定至少一个
key:缓存的 key,可以为空,如果指定要按照 SpEL 表达式编写,如果不指定,则缺省按照方法的所有参数进行组合
condition:缓存的条件,可以为空,使用 SpEL 编写,返回 true 或者 false,只有为 true 才进行缓存
③ @
CacheEvict(清除或缓存)
@CacheEvict是Spring框架提供的一个缓存注解,用于标记方法执行后清除缓存中的数据
java@CacheEvict(value = "xx",key = "'cid:'+#cid",allEntries = true) int deleteByPrimaryKey(Integer cid);
value:缓存位置的一段名称,不能为空
key:缓存的key,默认为空,表示使用方法的参数类型及参数值作为key,支持SpEL
condition:触发条件,满足条件就加入缓存,默认为空,表示全部都加入缓存,支持SpEL
allEntries:true表示清除value中的全部缓存,默认为false
三,Redis缓存的击穿、穿透、雪崩
缓存中常见的三种现象:击穿、穿透、雪崩
① 击穿
当缓存中不存在某个key的数据,而有大量并发请求访问这个key时,这些请求会直接穿过缓存,去访问数据库,导致数据库压力过大,甚至宕机
解决方法:
使用互斥锁或分布式锁,保证只有一个线程去访问数据库,其他线程等待结果即可
② 穿透
如果在请求数据时,在缓存层和数据库层都没有找到符合条件的数据,也就是说,在缓存层和数据库层都没有命中数据,那么这种情况就叫作缓存穿透。
解决方法:
在缓存中预先设置这个key对应的空值或默认值,避免大量请求直接访问数据库
图例:
③ 雪崩
当缓存中的大量数据同时失效,而且这些数据被大量请求访问时,这些请求会直接访问数据库,导致数据库压力过大,甚至宕机
解决方法:
缓存数据的失效时间设置随机,避免大量数据同时失效。
使用多级缓存架构,避免单点故障。
使用熔断机制,当缓存失效时,暂时屏蔽对数据库的访问,避免压力过大
图例: