Spring Boot 整合 spring cache

谁借莪１个温暖的怀抱￠ 2022-01-13 14:21 253阅读 0赞

[2019独角兽企业重金招聘Python工程师标准>>> ][2019_Python_] ![hot3.png][]

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## 一、JSR107 ##

JSR107是Java的一套缓存规范，**Java Caching**定义了5个核心接口，分别是**CachingProvider**, **CacheManager**, **Cache**, **Entry** 和 **Expiry**。

*  **CachingProvider**：定义了创建、配置、获取、管理和控制多个CacheManager。一个应用可 以在运行期访问多个CachingProvider。
 *  **CacheManager**：定义了创建、配置、获取、管理和控制多个唯一命名的Cache，这些Cache 存在于CacheManager的上下文中。一个CacheManager仅被一个CachingProvider所拥有。
 *  **Cache**：是一个类似Map的数据结构并临时存储以Key为索引的值。一个Cache仅被一个 CacheManager所拥有。
 *  **Entry**：是一个存储在Cache中的key-value对。
 *  **Expiry**：每一个存储在Cache中的条目有一个定义的有效期。一旦超过这个时间，条目为过期 的状态。一旦过期，条目将不可访问、更新和删除。缓存有效期可以通过ExpiryPolicy设置。

![8137915a8cd27d0811f5e8464c8c148ecc1.jpg][]

## 二、Spring 缓存抽象 ##

Spring从3.1开始定义了**org.springframework.cache.Cache** 和**org.springframework.cache.CacheManager** 接口来统一不同的缓存技术; 并支持使用JCache(JSR-107)注解简化我们开发;

*  默认使用 **ConcurrenMapCacheManager**
 *  **Cache**接口为缓存的组件规范定义，包含缓存的各种操作集合;
 *  **Cache**接口下Spring提供了各种**xxxCache**的实现;如**RedisCache**，**EhCacheCache** , **ConcurrentMapCache**等;
 *  每次调用需要缓存功能的方法时，Spring会检查检查指定参数的指定的目标方法是否 已经被调用过;如果有就直接从缓存中获取方法调用后的结果，如果没有就调用方法 并缓存结果后返回给用户。下次调用直接从缓存中获取。
 *  使用Spring缓存抽象时我们需要关注以下两点;
    
     *  1、确定方法需要被缓存以及他们的缓存策略
     *  2、从缓存中读取之前缓存存储的数据

![5b55b9f0e6eb450fd9da02cd354a23b448a.jpg][]

## 三、几个重要概念&缓存注解 ##

![02353643a057be629e1abac0e74746f2714.jpg][]

![d5629967a273fed625b0fda8d202620581c.jpg][]

![aaddca1c16d7adbc4dfdbc23a17c8ac5714.jpg][]

## 四、整合redis实现缓存 ##

创建项目springboot-cache，引入**spring-boot-starter-cache**、**spring-boot-starter-data-redis** 的依赖。

### 1. 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    
    	<groupId>com.gf</groupId>
    	<artifactId>springboot-cache</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>jar</packaging>
    
    	<name>springboot-cache</name>
    	<description>Demo project for Spring Boot</description>
    
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.0.5.RELEASE</version>
    		<relativePath/> 
    	</parent>
    
    	<properties>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    		<java.version>1.8</java.version>
    	</properties>
    
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-cache</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-data-redis</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-web</artifactId>
    		</dependency>
    
    		<dependency>
    			<groupId>com.alibaba</groupId>
    			<artifactId>fastjson</artifactId>
    			<version>1.2.51</version>
    		</dependency>
    
    		<dependency>
    			<groupId>mysql</groupId>
    			<artifactId>mysql-connector-java</artifactId>
    			<scope>runtime</scope>
    		</dependency>
    
    		<dependency>
    			<groupId>org.projectlombok</groupId>
    			<artifactId>lombok</artifactId>
    			<version>1.18.2</version>
    			<scope>provided</scope>
    		</dependency>
    
    		<dependency>
    			<groupId>com.baomidou</groupId>
    			<artifactId>mybatis-plus-boot-starter</artifactId>
    			<version>3.0.1</version>
    		</dependency>
    
    		<dependency>
    			<groupId>org.apache.velocity</groupId>
    			<artifactId>velocity</artifactId>
    			<version>1.7</version>
    		</dependency>
    
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    	</dependencies>
    
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    
    </project>

### 2. RedisConfig ###

我们用redis自定义CacheManager，同时自定义序列化方式。

\*\*注意：\*\*lombok 的getter setter 和 编辑器生成的 getter setter，有时会存在差异。字段 dID ，编辑器生成的是 getdId() ，而lombok 编译成的是getDId()，这中情况会可能会导致序列化成json时多出一个字段 json串出现 did 和 dId ，出现这种情况时，对与该实体可以弃用lombok，手动生成来解决。

@Configuration
    public class RedisConfig {
    
        @Bean
        public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
            RedisTemplate<Object, Object> template = new RedisTemplate<>();
            template.setConnectionFactory(redisConnectionFactory);
    
            GenericFastJsonRedisSerializer serializer = new GenericFastJsonRedisSerializer();
    
            ParserConfig.getGlobalInstance().addAccept("com.gf.");
    
            //key序列化方式
            template.setKeySerializer(new StringRedisSerializer());
            //value序列化
            template.setValueSerializer(serializer);
            //value hashmap序列化
            template.setHashValueSerializer(serializer);
            template.afterPropertiesSet();
    
            return template;
        }
    
        @Bean
        public RedisCacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
    
            RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig();
    
            GenericFastJsonRedisSerializer serializer = new GenericFastJsonRedisSerializer();
    
            ParserConfig.getGlobalInstance().addAccept("com.gf.");
    
            config = config.serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer()))
                    .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(serializer))
                    .disableCachingNullValues();
    
            RedisCacheManager.RedisCacheManagerBuilder builder = RedisCacheManager.builder(redisConnectionFactory).cacheDefaults(config);
    
    
            return builder.build();
        }
    
    
    }

### 3. EmployeeServiceImpl ###

@Service
    public class EmployeeServiceImpl extends ServiceImpl<EmployeeMapper, Employee> implements EmployeeService {
    
        @Cacheable(value = "emp" , key = "#root.args[0]" , condition = "#id > 0" , unless = "#result eq null")
        @Override
        public Employee getById(Serializable id) {
            System.out.println("getById");
            return super.getById( id );
        }
    
        @Override
        @CachePut(value = "emp", key = "#root.args[0].id", unless = "#result eq null ")
        public Employee updateEmployeeById(Employee entity) {
            boolean res = super.updateById( entity );
            if (res){
                return entity;
            }
            return null;
        }
    
        @CacheEvict(value = "emp", key = "#root.args[0]", condition = "#result eq true")
        @Override
        public boolean removeById(Serializable id) {
            return super.removeById( id );
        }
        
    }

### 4. 启动类 SpringbootCacheApplication ###

使用\*\*@EnableCaching\*\*开启缓存

@EnableCaching
    @SpringBootApplication
    public class SpringbootCacheApplication {
    
    	public static void main(String[] args) {
    		SpringApplication.run( SpringbootCacheApplication.class, args);
    	}
    }

之后我们通过postman测试。

## 源码 ##

[https://github.com/gf-huanchupk/SpringBootLearning][https_github.com_gf-huanchupk_SpringBootLearning]

## 关注我 ##

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转载于:https://my.oschina.net/u/2367201/blog/3054850

[2019_Python_]: https://my.oschina.net/u/2663968/blog/3061697
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