缓存架构中的服务详解！SpringBoot中二级缓存服务的实现
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创建缓存服务
创建缓存服务接口项目
- 创建myshop-service-redis-api项目,该项目只负责定义接口
- 创建项目的pom.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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.oxford</groupId>
<artifactId>myshop-dependencies</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../myshop-dependencies/pom.xml</relativePath>
</parent>
<artifactId>myshop-service-redis-api</artifactId>
<packaging>jar</packaging>
</project>
- 定义数据Redis接口RedisService:
package com.oxford.myshop.service.redis.api
public interface RedisService{
void set(String key,Object value);
void set(String key,Object value,int seconds);
void del(String key);
Object get(String key);
}
创建缓存服务提供者项目
- 创建myshop-service-redis-provider项目,该项目用作缓存服务提供者
- 创建项目的pom.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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.oxford</groupId>
<artifactId>myshop-dependencies</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../myshop-dependencies/pom.xml</relativePath>
</parent>
<artifactId>myshop-service-redis-api</artifactId>
<packaging>jar</packaging>
<dependencies>
<!-- Spring Boot Starter Settings-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!--Common Setting-->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-pool2</artifactId>
</dependency>
<dependency>
<groupId>de.javakaffee</groupId>
<artifactId>kryo-serializers</artifactId>
</dependency>
<!--Project Settings-->
<dependency>
<groupId>com.oxford</groupId>
<artifactId>my-shop-commons-dubbo</artifactId>
<version>${Project.parent.version}</version>
</dependency>
<dependency>
<groupId>com.oxford</groupId>
<artifactId>my-shop-service-redis-api</artifactId>
<version>${Project.parent.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<mainClass>com.oxford.myshop.service.redis.provider.MyshopServiceRedisProviderApplication</mainClass>
</configuration>
</plugin>
</plugins>
</build>
</project>
Redis底层实现的Java的lettuce客户端
- 创建缓存服务接口实现类RedisServiceImpl
package com.oxford.myshop.service.redis.provider.api.impl;
@Service(version="${service.versions.redis.v1}")
public class RedisServiceImpl implements RedisService{
@Override
public void set(String key,Object value){
redisTemplate.opsForValue().set(key,value);
}
@Override
public void set(String key,Object value,int seconds){
redisTemplate.opsForValue().set(key,value,seconds,TimeUnit.SECONDS);
}
@Override
public void del(String key){
redisTemplate.delete(key);
}
@Override
public Object get(String key){
return redisTemplate.opsForValue().get(key);
}
}
- 创建启动类SpringBootApplication
package com.oxford.myshop.service.redis.provider;
import com.alibaba.dubbo.container.Main;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
@EnableHystrix
@EnableHystrixDashboard
public class MyShopServiceRedisrProviderApplication {
public static void main(String[]args) {
SpringApplication.run(MyShopServiceRedisProviderApplication.class,args);
Main.main(args);
}
}
- 创建配置文件application.yml
spring:
application:
name: myshop-service-redis-provider
redis:
lettuce:
pool:
max-active: 8
max-idle: 8
max-wait: -1ms
min-idle: 0
sentinel:
master: mymaster
nodes: 192.168.32.255:26379,192.168.32.255:26380,192.168.32.255:26381
server:
port: 8503
services:
version:
redis:
v1: 1.0.0
user:
v1: 1.0.0
dubbo:
scan:
basePackages: com.oxford.myshop.service.redis.provider.api.impl
application:
id: com.oxford.myshop.service.redis.provider.api
name: com.oxford.myshop.service.redis.provider.api
qos-port: 22224
qos-enable: true
protocal:
id: dubbo
name: dubbo
port: 20883
status: server
serialization: kryo
regitry:
id: zookeeper
address: zookeeper://localhost:2181?backup=192.168.32.255:2182,192.168.32.255:2183
management:
endpoint:
dubbo:
enabled: true
dubbo-shutdown:
enabled: true
dubbo-configs:
enabled: true
dubbo-sevicies:
enabled: true
dubbo-reference:
enabled: true
dubbo-properties:
enabled: true
health:
dubbo:
status:
defaults: memory
extras: load,threadpool
创建缓存服务消费者项目
- 在pom文件中引入redis接口依赖
- 在缓存服务消费者项目的ServiceImpl中调用RedisService
@Reference(version="services.versions.redis.v1")
private RedisService redisService;
MyBatis Redis二级缓存
MyBatis缓存
- 一级缓存:
- MyBatis会在表示会话的SqlSession对象中建立一个简单的缓存: 将每次查询到的结果缓存起来,当下次查询的时候,如果判断先前有个完全一样的查询,会直接从缓存中直接将结果取出,返回给用户,不需要再进行一次数据库查询
- 一级缓存是SqlSession级别的缓存:
- 在操作数据库时需要构造SqlSession对象
- 对象中有一个(内存区域)数据结构(HashMap)用于存储缓存数据
- 不同的SqlSession之间的缓存数据区域(HashMap)互不影响,
- 一级缓存的作用域是同一个SqlSession
- 在同一个SqlSession中两次执行相同的SQL语句: 第一次执行完毕会将数据库中查询的数据写到缓存(内存),第二次会从缓存中获取数据,将不再从数据库查询,从而提高查询效率
- 当一个SqlSession结束后该SqlSession中的一级缓存就不存在了
- MyBatis默认开启一级缓存
- 二级缓存:
- 二级缓存是Mapper级别的缓存: 多个SqlSession去操作同一个Mapper的SQL语句,多个SqlSession去操作数据库得到数据会存在二级缓存区域,多个SqlSession可以共用二级缓存,二级缓存是跨SqlSession的
- 二级缓存的作用域是mapper的同一个namespace
- 不同的SqlSession两次执行相同namespace下的SQL语句且向SQL中传递参数也相同即最终执行相同的SQL语句: 第一次执行完毕会将数据库中查询的数据写到缓存(内存),第二次会从缓存中获取数据将不再从数据库查询,从而提高查询效率
- MyBatis默认没有开启二级缓存,需要在setting全局参数中配置开启二级缓存
配置MyBatis二级缓存
SpringBoot中开启MyBatis二级缓存
- 在myshop-service-user-provider的配置文件中开启MyBatis二级缓存
spring:
application:
name: myshop-service-user-provider
datasource:
druid:
url: jdbc:mysql://localhost:3306/myshop?useUnicode=true&characterEncoding=utf-8&useSSL=false
username: root
password: 123456
initial-size: 1
min-idle: 1
main-active: 20
test-on-borrow: true
driver-class-name: com.mysql.cj.jdbc.Driver
redis:
lettuce:
pool:
max-active: 8
max-idle: 8
max-wait: -1ms
min-idle: 0
sentinel:
master: mymaster
nodes: 192.168.32.255:26379,192.168.32.255:26380,192.168.32.255:26381
server:
port: 8501
# MyBatis Config properties
mybatis:
configuration:
cache-enabled: true
type-aliases-package: com.oxford.myshop.commons.domain
mapper-location: classpath:mapper/*.xml
services:
version:
redis:
v1: 1.0.0
user:
v1: 1.0.0
dubbo:
scan:
basePackages: com.oxford.myshop.service.user.provider.api.impl
application:
id: com.oxford.myshop.service.user.provider.api
name: com.oxford.myshop.service.user.provider.api
qos-port: 22222
qos-enable: true
protocal:
id: dubbo
name: dubbo
port: 20001
status: server
serialization: kryo
regitry:
id: zookeeper
address: zookeeper://localhost:2181?backup=192.168.32.255:2182,192.168.32.255:2183
management:
endpoint:
dubbo:
enabled: true
dubbo-shutdown:
enabled: true
dubbo-configs:
enabled: true
dubbo-sevicies:
enabled: true
dubbo-reference:
enabled: true
dubbo-properties:
enabled: true
health:
dubbo:
status:
defaults: memory
extras: load,threadpool
- 在myshop-commons-mapper的pom.xml中增加redis依赖:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifacted>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-pool2</artifacted>
</dependency>
实体类实现序列化接口并声明序列号
private static final long serialVersionUID = 82897704415244673535L
IDEA生成序列号方法:
- 使用GenerateSerialVersionUID插件生成,安装完插件后在实现了序列化接口的类中
- 使用快捷键Alt+Insert即可呼出生成菜单,即可自动生成序列号
实现Mybatis Cache接口,自定义缓存为Redis
- 在myshop-commons项目中创建ApplicationContextHolder类
package com.oxford.myshop.commons.context;
@Component
public class ApplicationContextHolder implements ApplicationContextAware,DisposableBean{
private static final Logger logger=LoggerFactory.getLogger(ApplicationContext.class);
private static ApplicationContext applicationContext;
/**
* 获取存储在静态变量中的ApplicationContext
*/
public static ApplicationContext getApplicationContext(){
assertContextInjected();
return applicationContext;
}
/**
* 从静态变量applicationContext中获取Bean,自动转型成所赋值对象的类型
*/
public static <T> T getBean(String name){
assertContextInjected();
return (T) applicationContext.getBean(name);
}
/**
* 从静态变量applicationContext中获取Bean,自动转型成所赋值对象的类型
*/
public static <T> T getBean(Class<T> clazz){
assertContextInjected();
return (T) applicationContext.getBean(clazz);
}
/**
* 实现DisposableBean接口,在Context关闭时清理静态变量
*/
public void destroy() throws Exception{
logger.debug("清除 SpringContext 中的 ApplicationContext: {}",applicationContext);
applicationContext=null;
}
/**
* 实现ApplicationContextAware接口,注入Context到静态变量中
*/
public void setApplicationContext(ApplicationContext applicationContext) throws BeanException{
ApplicationContext.applicationContext=applicationContext;
}
/**
* 断言Context已经注入
*/
private static void assertContextInjected(){
Validate.validState(applicationContext !=null,"applicationContext 属性未注入,请在配置文件中配置定义ApplicationContextContext");
}
}
- 在myshop-commons-mapper项目中创建一个RedisCache的工具类
package com.oxford.myshop.commons.utils;
public class RedisCache implements Cache{
private static final Logger logger=LoggerFactory.getLogger(RedisCache.class);
private final ReadWriteLock readWriteLock=new ReentranReadWriteLock();
private final String id;
private RedisTemplate redisTemplate;
private static final long EXPIRE_TIME_IN_MINUTES=30 // redis过期时间
public RedisCache(String id){
if(id==null){
throw new IllegalArgumentException("Cache instances require an ID");
}
this.id=id;
}
@Override
public String getId(){
return id;
}
/**
* Put query result to redis
*/
@Override
public void putObject(Object key,Object value){
try{
RedisTemplate redisTemplate=getRedisTemplate();
ValueOperations opsForValue=redisTemplate.opsForValue();
opsForValue.set(key, value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES);
logger.debug("Put query result to redis");
}catch(Throwable t){
logger.error("Redis put failed",t);
}
}
/**
* Get cached query result from redis
*/
@Override
public Object getObject(Object key){
try{
RedisTemplate redisTemplate=getRedisTemplate();
ValueOperations opsForValue=redisTemplate.opsForValue();
opsForValue.set(key, value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES);
logger.debug("Get cache query result from redis");
return opsForValue.get(key);
}catch(Throwable t){
logger.error("Redis get failed, fail over to db");
return null;
}
}
/**
* Get cached query result from redis
*/
@Override
public Object getObject(Object key){
try{
RedisTemplate redisTemplate=getRedisTemplate();
ValueOperations opsForValue=redisTemplate.opsForValue();
opsForValue.set(key, value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES);
logger.debug("Get cache query result from redis");
return opsForValue.get(key);
}catch(Throwable t){
logger.error("Redis get failed, fail over to db");
return null;
}
}
/**
* Remove cached query result from redis
*/
@Override
@SuppressWarnings("unchecked")
public Object removeObject(Object key){
try{
RedisTemplate redisTemplate=getRedisTemplate();
redisTemplate.delete(key);
logger.debug("Remove cached query result from redis");
}catch(Throwable t){
logger.error("Redis remove failed");
}
return null;
}
/**
* Clear this cache instance
*/
@Override
public void clear(){
RedisTemplate redisTemplate=getRedisTemplate();
redisTemplate.execute((RedisCallback)->{
connection.flushDb();
return null;
});
logger.debug("Clear all the cached query result from redis");
}
@Override
public int getSize(){
return 0;
}
@Override
public ReadWriteLock getReadWriteLock(){
return readWriteLock;
}
private RedisTemplate getRedisTemplate(){
if(redisTemplate==null){
redisTemplate=ApplicationContextHolder.getBean("redisTemplate");
}
return redisTemplate;
}
}
Mapper接口类中标注注解
- 在Mapper接口类上标注注解,声明使用二级缓存
@CacheNamespace(implementation=RedisCache.class)
文章来源：https://www.cnblogs.com/chova/archive/2021/05/22/14799627.html
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