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
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