1、pom 加入

        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-cache -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.github.ben-manes.caffeine/caffeine -->
        <dependency>
            <groupId>com.github.ben-manes.caffeine</groupId>
            <artifactId>caffeine</artifactId>
            <version>2.8.8</version>
        </dependency>

2、配置

# caffeine cache configuration
spring.cache.cache-names=user
spring.cache.caffeine.spec=initialCapacity=50,maximumSize=500,expireAfterWrite=30s
spring.cache.type=caffeine

3、启用缓存

@EnableCaching
@Log4j2
@SpringBootApplication
public class TestApplication {

    public static void main(String[] args) {
        Main.run(TestApplication.class, args);
    }
}

4、测试代码-模型

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User implements Serializable {

    private Long id;
    private String name;
}

5、测试代码-服务类

@Service
@Log4j2
public class UserService {

    private static List<User> users = new ArrayList<>();

    static {
        User user1 = new User(1L, "lolo");
        User user2 = new User(2L, "popo");
        users.add(user1);
        users.add(user2);
    }

    @CachePut(value = "user", key = "#id")
    public User saveOrUpdateUser(Long id, String name) {
        log.error("saveOrUpdateUser id:{}", id);
        log.error("saveOrUpdateUser users:{}", users.size());
        User findUser = getUser(id);
        if (findUser == null) {
            findUser = new User(id, name);
            users.add(findUser);
        } else {
            findUser.setName(name);
        }
        return findUser;
    }

    @Cacheable(value = "user", key = "#id")
    public User getUser(Long id) {
        log.error("getUser:{}", id);
        Predicate<User> idPredicate = value -> value.getId().equals(id);

        Optional<User> optionalUser = users.stream().filter(idPredicate).findFirst();
        if (optionalUser.isPresent()) {
            User findUser = optionalUser.get();
            return findUser;
        }

        return null;
    }

    @CacheEvict(value = "user", key = "#id")
    public void delete(Long id) {
        log.error("delete:{}", id);
        User user = getUser(id);
        users.remove(user);
    }
}

6、控制器代码

@Log4j2
@Api(value = "首页")
@RestController
public class IndexController {

    private final RedisTemplate<String, String> redisTemplate;
    private final UserService userService;

    public IndexController(RedisTemplate<String, String> redisTemplate, UserService userService) {
        this.redisTemplate = redisTemplate;
        this.userService = userService;
    }

    @ApiOperation(value = "新增或修改用户")
    @PostMapping("/saveOrUpdateUser")
    public ResponseEntity<Result<User>> saveOrUpdateUser(
            @ApiParam(value = "用户ID") @RequestParam Long id,
            @ApiParam(value = "用户姓名") @RequestParam String name
    ) {
        User user = userService.saveOrUpdateUser(id, name);
        return ResultUtils.ok(user, "保存成功");
    }

    @ApiOperation(value = "查询用户")
    @GetMapping("/getUserById")
    public ResponseEntity<Result<User>> getUserById(
            @ApiParam(value = "用户ID") @RequestParam Long id
    ) {
        User user = userService.getUser(id);
        return ResultUtils.ok(user, "查询成功");
    }

    @ApiOperation(value = "删除用户")
    @PostMapping("/deleteById")
    public ResponseEntity<Result<Long>> deleteById(
            @ApiParam(value = "用户ID") @RequestParam Long id
    ) {
        userService.delete(id);
        return ResultUtils.ok(id, "删除成功");
    }