SpringBoot与SpringCache概念用法大全

1.SpringCache的概念

首先我们知道jpa,jdbc这些东西都是一些规范，比如jdbc，要要连接到数据库，都是需要用到数据库连接，预处理，结果集这三个对象，无论是连接到mysql还是oracle都是需要用到这个三个对象的，这是一种规范，而SpringCache是一种作为缓存的规范，具体实现有redis,EhCahe等

2.SpringCache用法（redis版）

2.1 .SpringCache基本用法

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-parent</artifactId>
       <version>2.6.3</version>
       <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.yl</groupId>
   <artifactId>cache_redis</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>cache_redis</name>
   <description>Demo project for Spring Boot</description>
   <properties>
       <java.version>11</java.version>
   </properties>
   <dependencies>
       <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-cache</artifactId>
       </dependency>
           <artifactId>spring-boot-starter-data-redis</artifactId>
           <artifactId>spring-boot-starter-web</artifactId>

<artifactId>spring-boot-starter-test</artifactId>
           <scope>test</scope>
   </dependencies>
   <build>
       <plugins>
           <plugin>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-maven-plugin</artifactId>
           </plugin>
       </plugins>
   </build>
</project>

2.application.properties

# redis的配置
spring.redis.host=192.168.244.135
spring.redis.port=6379
spring.redis.password=root123

3.实体类

package com.yl.cache_redis.domain;
import java.io.Serializable;
public class User implements Serializable {
   private Integer id;
   private String username;
   private String password;
   public Integer getId() {
       return id;
   }
   public void setId(Integer id) {
       this.id = id;
   }
   public String getUsername() {
       return username;
   }
   public void setUsername(String username) {
       this.username = username;
   }
   public String getPassword() {
       return password;
   }
   public void setPassword(String password) {
       this.password = password;
   }
   @Override
   public String toString() {
       return "User{" +
               "id=" + id +
               ", username='" + username + '\'' +
               ", password='" + password + '\'' +
               '}';
   }
}

4.service

package com.yl.cache_redis;

import com.yl.cache_redis.domain.User;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
@Service
public class UserService {
   @Cacheable(cacheNames = "u1") //这个注解作用就是将方法的返回值存到缓存中
   public User getUserById(Integer id) {
       System.out.println("getUserById:" + id);
       User user = new User();
       user.setId(id);
       user.setUsername("root");
       user.setPassword("root");
       return user;
   }
}

5.主程序，加上开启缓存的注解

package com.yl.cache_redis;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
@SpringBootApplication
@EnableCaching //开启缓存功能
public class CacheRedisApplication {
   public static void main(String[] args) {
       SpringApplication.run(CacheRedisApplication.class, args);
   }
}

6.测试

6.1）userservice没加@Cacheable注解时

6.2）userservice加@Cacheable注解后，发现sevice中的方法只调用了一次

6.3）在redis中也可以看到缓存中有数据，key为定义好的cacheNames+::+方法的参数

2.2 .SpringCache自定义缓存key

1.SpringCache默认使用cacheNames和方法中的参数结合组成key的，那么如果有多个参数呢？它又是如何组成key的呢？我们可以指定key吗？

2.如何自定义key呢？

1）自定义key

package com.yl.cache_redis;

import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.stereotype.Component;
import java.lang.reflect.Method;
import java.util.Arrays;
@Component
public class MyKeyGenerator implements KeyGenerator {
   @Override
   public Object generate(Object target, Method method, Object... params) {
       return target.toString() + ":" + method.getName() + ":" + Arrays.toString(params);
   }
}

2）测试

2.3 .SpringCache更新缓存

1.使用@CachePut注解来更新，注意：@CachePut中的key要和@Cacheable中的key一样，否则更新不了！

2.4 .SpringCache清空缓存

1.使用@CacheEvict注解，主要key和要@Cacheable中的key一致

2.测试

2.5 .SpringCache其他用法

1.@Caching注解，可以组合多个注解

2.@CacheConfig注解

3.SpringCache用法（EhCache版）

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-parent</artifactId>
       <version>2.6.3</version>
       <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.yl</groupId>
   <artifactId>ehcache</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>ehcache</name>
   <description>Demo project for Spring Boot</description>
   <properties>
       <java.version>11</java.version>
   </properties>
   <dependencies>
       <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-cache</artifactId>
       </dependency>
           <artifactId>spring-boot-starter-web</artifactId>

<artifactId>spring-boot-starter-test</artifactId>
           <scope>test</scope>
           <groupId>net.sf.ehcache</groupId>
           <artifactId>ehcache</artifactId>
           <version>2.10.6</version>
   </dependencies>
   <build>
       <plugins>
           <plugin>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-maven-plugin</artifactId>
           </plugin>
       </plugins>
   </build>
</project>

2.实体类

package com.yl.ehcache.model;
import java.io.Serializable;
public class User implements Serializable {
   private Integer id;
   private String username;
   private String password;
   public Integer getId() {
       return id;
   }
   public void setId(Integer id) {
       this.id = id;
   }
   public String getUsername() {
       return username;
   }
   public void setUsername(String username) {
       this.username = username;
   }
   public String getPassword() {
       return password;
   }
   public void setPassword(String password) {
       this.password = password;
   }
   @Override
   public String toString() {
       return "User{" +
               "id=" + id +
               ", username='" + username + '\'' +
               ", password='" + password + '\'' +
               '}';
   }
}

3.service

package com.yl.ehcache.service;

import com.yl.ehcache.model.User;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
@Service
public class UserService {
   @Cacheable(cacheNames = "user")
   public User getUserById(Integer id) {
       System.out.println("getUserById()...");
       User user = new User();
       user.setId(id);
       user.setUsername("root");
       user.setPassword("root");
       return user;
   }
   @CacheEvict(cacheNames = "user")
   public void delete(Integer id) {
       System.out.println("delete");
}

4.主程序

package com.yl.ehcache;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
@SpringBootApplication
@EnableCaching
public class EhcacheApplication {
   public static void main(String[] args) {
       SpringApplication.run(EhcacheApplication.class, args);
   }
}

5.ehcache.xml

<ehcache>
   <diskStore path="java.io.tmpdir/shiro-spring-sample"/>
   <defaultCache
           maxElementsInMemory = "1000"
           eternal = "false"
           timeToIdleSeconds = "120"
           timeToLiveSeconds = "120"
           overflowToDisk = "false"
           diskPersistent = "false"
           diskExpiryThreadIntervalSeconds = "120"/>
   <cache name = "user"
          maxElementsInMemory = "1000"
          eternal = "false"
          overflowToDisk = "true"
          diskPersistent = "true"
          diskExpiryThreadIntervalSeconds = "600"/>
</ehcache>

6.测试

来源：https://blog.csdn.net/weixin_41359273/article/details/122823344