目录
一、注解参数说明
1.1 属性说明
1.1.1 value/cacheNames 属性
- 1.这两个属性代表的意义相同
- 2.用来指定缓存组件的名称,将方法的返回结果存进缓存的名称
- 3.定义为数组时,可以存到多个缓存key中
1.1.2 key属性
- 1.指定缓存数据的key
1.#root.method.name:当前被调用的方法名
2.#root.methodName:当前被调用的方法
3.#root.target:当前被调用的目标对象
4.#root.targetClass:当前被调用的目标对象类
5.#root.args[0]:当前被调用的方法的参数列表
6.#root.caches[0].name:当前方法调用使用的缓存列表(@Cacheable(value={"cache1","cache2"}))
7.#id、#p0、#a0:方法参数的名字,可以#参数名,也可以使用 #p0或#a0 的形式,0代表参数的索引
8.#result:方法执行后的返回值(仅当方法执行之后的判断有效,如’unless’、@cacheput和@cacheevict的表达式beforeInvocation=false)
- 2.redis作为缓存时,redis中的key为value::key
- 3.方法没有参数时,key=new SimpleKey()
- 4.方法有一个参数时,key=参数的值
- 5.方法有多个参数时,key=new SimpleKey(params);
1.1.3 keyGenerator属性
- 1.key 的生成器
- 2.可以自定义key的生成器的组件id
- 3.key与keyGenerator二选一使用
- 4.可以自定义配置类,将 keyGenerator 注册到 IOC 容器
1.1.4 cacheManager属性
- 1.用来指定缓存管理器
- 2.对不同的缓存技术,实现不同的cacheManager,spring定义了一些 cacheManger的实现
- 3.SimpleCacheManager:使用简单的Collection来存储缓存(默认)
- 4.ConcurrentMapCacheManager:使用ConcurrentMap作为缓存技术
- 5.NoOpCacheManager:测试用
- 6.EhCacheCacheManager:使用EhCache作为缓存技术,hibernate经常用
- 7.GuavaCacheManager:使用google的guava的GuavaCache作为缓存技术
- 8.HazelcastCacheManager:使用Hazelcast作为缓存技术
- 9.JCacheCacheManager:使用JCache标准的实现作为缓存技术,如Apache Commons JCS
- 10.RedisCacheManager:使用Redis作为缓存技术
1.1.5 cacheResolver属性
- 1.指定自定义的缓存管理器
- 2.cacheManager缓存管理器与cacheResolver自定义解析器二选一使用
1.1.6 condition属性
- 1.符合指定的条件才可以缓存
- 2.可以通过 SpEL 表达式进行设置
1.1.7 unless 属性
- 1.unless的条件为 true 时,方法的返回值不会被缓存
- 2.可以在获取到结果后进行判断
1.1.8 sync 属性
- 1.是否使用同步模式
- 2.异步模式下 unless 属性不可用
- 3.sync=true:同步模式,若多个线程尝试为同一个key缓存值,当一个线程缓存成功后,其它线程便直接拿缓存后的数据,不会再去查库缓存,能解决缓存击穿问题;一个线程去新建,新建成功后其它线程才能拿
- 4.默认是false
1.2 @Cacheable注解
- 1.每次执行方法前都会检查cache中是否存在相同key的缓存,如果存在就不再执行该方法,直接从缓存中获取结果进行返回,如果不存在则会执行该方法并将结果存入指定key的缓存中
1.3 @CachePut注解
- 1.在执行方法前不会去检查缓存中是否存在key的缓存,每次都会执行该方法,并将执行结果存入指定key的缓存中
- 2.使用在保存,更新方法中
- 3.标注在类上和方法
1.4 @CacheEvict注解
- 1.标注在需要清除缓存的方法或类
- 2.标记在类上时表示其中所有方法的执行都会触发缓存的清除操作
- 3.@CacheEvict可以指定的属性有value、key、condition、allEntries和beforeInvocation
1.4.1 allEntries属性
- 1.allEntries为true时,清除value属性值中的所有缓存,更有效率
- 2.默认为false,可以指定清除value属性值下具体某个key的缓存
1.4.2 beforeInvocation属性
- 1.默认是false,即在方法执行成功后触发删除缓存的操作
- 2.如果方法抛出异常未能成功返回,不会触发删除缓存的操作
- 3.当改为true时,方法执行之前会清除指定的缓存,这样不论方法执行成功还是失败都会清除缓存
二、代码示例
2.1 基本框架搭建
- 1.导入依赖
<?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">
<parent>
<artifactId>springboot-learning</artifactId>
<groupId>com.learning</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>springboot-cache</artifactId>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
<dependencies>
<!-- springboot web启动类-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
<!-- mybatis-plus依赖包 -->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.4.2</version>
</dependency>
<!-- mysql依赖包 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!-- cache依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-cache</artifactId>
</dependency>
<!-- 用redis作为缓存 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
</dependencies>
</project>
- 2.application.yaml配置
spring:
datasource:
url: jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=false
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: root
cache:
type: redis
redis:
host: 127.0.0.1
port: 6379
mybatis-plus:
global-config:
db-config:
id-type: auto
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
- 3.接口类
package com.learning.cache.controller;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
/**
* @Description 接口类
*/
@RestController
@RequestMapping("student")
public class StudentController {
@Autowired
private StudentService studentService;
@ResponseBody
@GetMapping("/list")
public List<Student> getList(){
return studentService.list();
}
@ResponseBody
@GetMapping("/{id}")
public Student getById(@PathVariable String id){
return studentService.getById(id);
}
@ResponseBody
@GetMapping("/page")
public Page<Student> getPage(@RequestParam int size, @RequestParam int current){
return studentService.page(size, current);
}
@ResponseBody
@PostMapping("/save")
public Student save(@RequestBody Student student){
return studentService.save(student);
}
@DeleteMapping("/{id}")
public boolean delete(@PathVariable String id){
return studentService.delete(id);
}
}
- 4.service实现类
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Cacheable(value={"com:learning:cache:list"})
@Override
public List<Student> list() {
return studentDao.selectList(null);
}
@Cacheable(value="com:learning:cache:one")
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
@Cacheable(value={"com:learning:cache:more"})
@Override
public Page<Student> page(int size, int current) {
Page<Student> page = new Page<>();
page.setCurrent(current);
page.setSize(size);
return studentDao.selectPage(page, null);
}
@Override
public Student save(Student student) {
int result = studentDao.insert(student);
if(result > 0){
return student;
}
return null;
}
@CacheEvict(value="com:learning:cache:one", allEntries = true)
@Override
public boolean delete(String id) {
int result = studentDao.deleteById(id);
if(result > 0){
return true;
}
return false;
}
}
- 5.service接口类
package com.learning.cache.service;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.entity.Student;
import java.util.List;
public interface StudentService {
List<Student> list();
Student getById(String id);
Page<Student> page(int size, int current);
Student save(Student student);
boolean delete(String id);
}
- 6.持久层类
package com.learning.cache.dao;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.learning.cache.entity.Student;
import org.apache.ibatis.annotations.Mapper;
/**
* @Description 学生持久层类
*/
@Mapper
public interface StudentDao extends BaseMapper<Student> {
}
- 7.启动类
package com.learning.cache;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
/**
* @Description 启动类
*/
@SpringBootApplication
// 开启启用缓存注解
@EnableCaching
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
- 8.配置类
package com.learning.cache.config;
import com.learning.cache.resolver.CustomCacheResolver;
import org.springframework.cache.interceptor.CacheResolver;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
/**
* @Description 自定义Key生成器
*/
@Configuration
public class CacheResolverConfig {
@Bean
public RedisCacheManager redisCacheManager(RedisConnectionFactory redisConnectionFactory) {
RedisCacheConfiguration cacheConfiguration = RedisCacheConfiguration.defaultCacheConfig()
.computePrefixWith(cacheName -> cacheName.concat(":"));
return RedisCacheManager.builder(redisConnectionFactory)
.cacheDefaults(cacheConfiguration)
.build();
}
@Bean("customCacheResolver")
public CacheResolver customCacheResolver(RedisConnectionFactory redisConnectionFactory) {
return new CustomCacheResolver(redisCacheManager(redisConnectionFactory));
}
}
package com.learning.cache.config;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.MappedStatement;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.UUID;
/**
* @Description 自定义Key生成器
*/
@Configuration
public class KeyGeneratorConfig {
@Bean("customKeyGenerator")
public KeyGenerator keyGenerator(){
return new KeyGenerator() {
@Override
public Object generate(Object o, Method method, Object... objects) {
return method.getName() + Arrays.asList(objects).toString() + UUID.randomUUID();
}
};
}
}
package com.learning.cache.config;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* @Description 分页配置类
*/
@Configuration
public class MybatisPlusConfig {
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor(){
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
return interceptor;
}
}
package com.learning.cache.resolver;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.cache.interceptor.*;
import org.springframework.context.expression.MethodBasedEvaluationContext;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import java.lang.reflect.Method;
import java.util.Collection;
/**
* @Description 自定义缓存解析器
*/
@Slf4j
public class CustomCacheResolver extends SimpleCacheResolver {
public CustomCacheResolver(CacheManager cacheManager) {
super(cacheManager);
}
@Override
public Collection<? extends Cache> resolveCaches(CacheOperationInvocationContext<?> context) {
// 拿到缓存
Collection<? extends Cache> caches = super.resolveCaches(context);
Object target = context.getTarget();
BasicOperation operation = context.getOperation();
Method method = context.getMethod();
Object[] args = context.getArgs();
ParameterNameDiscoverer paramNameDiscoverer = new DefaultParameterNameDiscoverer();
EvaluationContext evaluationContext = new MethodBasedEvaluationContext(context.getOperation(), context.getMethod(), context.getArgs(), paramNameDiscoverer);
Expression expression = (new SpelExpressionParser()).parseExpression(((CacheableOperation) context.getOperation()).getKey());
// 获取所有的缓存的名字
context.getOperation().getCacheNames().forEach(cacheName -> {
log.info("缓存的name:{}", cacheName);
String key = cacheName + ':' + expression.getValue(evaluationContext, String.class);
log.info("缓存的key全路径:{}", key);
});
// 返回缓存
return caches;
}
}
- 10.实体类
package com.learning.cache.entity;
import lombok.Data;
import java.io.Serializable;
/**
* @Description 学生类
*/
@Data
// 要实现Serializable接口,否则会报错
public class Student implements Serializable {
private String id;
private String name;
private Integer age;
}
2.2 value属性与cacheNames属性
2.2.1 单个缓存代码示例
package com.learning.cache.service.impl;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
// com:learning:cache会作为redis的key的一部分
@Cacheable(value="com:learning:cache:list")
@Override
public List<Student> list() {
return studentDao.selectList(null);
}
}
2.2.2 单个缓存效果截图
2.2.3 多个缓存代码示例
package com.learning.cache.service.impl;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
// 多个值,会将方法的返回结果存入到不同的缓存key中
@Cacheable(value={"com:learning:cache:list","cn:learning:cache:list"})
@Override
public List<Student> list() {
return studentDao.selectList(null);
}
}
2.2.4 多个缓存效果截图
2.3 key属性
2.3.1 方法没有参数示例
package com.learning.cache.service.impl;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Cacheable(value={"com:learning:cache:list"})
@Override
public List<Student> list() {
return studentDao.selectList(null);
}
}
2.3.2 方法没有参数截图
2.3.3 方法有一个参数示例
package com.learning.cache.service.impl;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
// String id 一个参数的key情况
@Cacheable(value={"com:learning:cache:one"})
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
}
2.3.4 方法有一个参数截图
2.3.5 方法有多个参数示例
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Cacheable(value={"com:learning:cache:more"})
@Override
public Page<Student> page(int size, int current) {
Page<Student> page = new Page<>();
page.setCurrent(current);
page.setSize(size);
return studentDao.selectPage(page, null);
}
}
2.3.6 方法有多个参数截图
2.3.7 指定key(从参数中指定)
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Cacheable(value="com:learning:cache:one", key="#id")
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
}
2.3.8 指定key截图
2.4 keyGenerator属性
2.4.1 自定义key生成器代码示例
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Cacheable(value="com:learning:cache:one", keyGenerator="customKeyGenerator")
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
}
package com.learning.cache.config;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.MappedStatement;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.lang.reflect.Method;
import java.sql.Statement;
import java.util.Arrays;
import java.util.UUID;
/**
* @Description 自定义Key生成器
*/
@Configuration
public class KeyGeneratorConfig {
@Bean("customKeyGenerator")
public KeyGenerator keyGenerator(){
return new KeyGenerator() {
@Override
public Object generate(Object o, Method method, Object... objects) {
return method.getName() + Arrays.asList(objects).toString() + UUID.randomUUID();
}
};
}
}
2.4.2 自定义key生成器截图
2.5 cacheResolver属性
2.5.1 自定义cacheResolver缓存解析器代码示例
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Cacheable(value="com:learning:cache:one",key="#id", cacheResolver="customCacheResolver")
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
}
package com.learning.cache.resolver;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.cache.interceptor.*;
import org.springframework.context.expression.MethodBasedEvaluationContext;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import java.lang.reflect.Method;
import java.util.Collection;
/**
* @Description 自定义缓存解析器
*/
@Slf4j
public class CustomCacheResolver extends SimpleCacheResolver {
public CustomCacheResolver(CacheManager cacheManager) {
super(cacheManager);
}
@Override
public Collection<? extends Cache> resolveCaches(CacheOperationInvocationContext<?> context) {
// 拿到缓存
Collection<? extends Cache> caches = super.resolveCaches(context);
Object target = context.getTarget();
BasicOperation operation = context.getOperation();
Method method = context.getMethod();
Object[] args = context.getArgs();
ParameterNameDiscoverer paramNameDiscoverer = new DefaultParameterNameDiscoverer();
EvaluationContext evaluationContext = new MethodBasedEvaluationContext(context.getOperation(), context.getMethod(), context.getArgs(), paramNameDiscoverer);
Expression expression = (new SpelExpressionParser()).parseExpression(((CacheableOperation) context.getOperation()).getKey());
// 获取所有的缓存的名字
context.getOperation().getCacheNames().forEach(cacheName -> {
log.info("缓存的name:{}", cacheName);
String key = cacheName + ':' + expression.getValue(evaluationContext, String.class);
log.info("缓存的key全路径:{}", key);
});
// 返回缓存
return caches;
}
}
2.5.2 自定义cacheResolver缓存解析器截图
2.6 condition属性
2.6.1 指定条件进行缓存代码示例
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
// 指定id为1的可以缓存
@Cacheable(value="com:learning:cache:one", condition = "#id eq '1'")
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
}
2.6.2 指定条件进行缓存截图
2.7 unless属性
2.7.1 指定条件不进行缓存代码示例
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
// 对查询结果为null的不做缓存,去掉的话会缓存空值
@Cacheable(value="com:learning:cache:one", unless = "#result == null")
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
}
2.7.2 结果为null的缓存截图
2.8 allEntries属性
2.8.1 清除全部缓存代码示例
package com.learning.cache.service.impl;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learning.cache.dao.StudentDao;
import com.learning.cache.entity.Student;
import com.learning.cache.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @Description 学生服务实现类
*/
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Cacheable(value="com:learning:cache:one")
@Override
public Student getById(String id) {
return studentDao.selectById(id);
}
@CacheEvict(value="com:learning:cache:one", allEntries = true)
@Override
public boolean delete(String id) {
int result = studentDao.deleteById(id);
if(result > 0){
return true;
}
return false;
}
}
2.8.2 先查2次缓存起来,然后删除1条,清除所有截图
三、注意事项
- 1.@CacheEvict注解测试的时候尽量调接口测试,不要用页面去触发,例如修改某条数据,清除分页数据缓存,修改完成后页面有可能会再次调用分页接口,导致分页的@Cableable仍然缓存,造成@CacheEvict失效的假象