Redis之sql缓存的具体使用

目录

• 1.环境搭建
• 2.Redis配置
• 3.功能实现
• 4.缓存注解的使用说明

1.环境搭建

 <!-- RedisTemplate -->
 <dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-data-redis</artifactId>
 </dependency>

spring:
  redis:
    host: 192.168.8.128
    port: 6380
    password: 1234
    database: 0
    timeout: 3000
    jedis:
      pool:
        max-wait: -1
        max-active: -1
        max-idle: 20
        min-idle: 10

2.Redis配置

package com.yzm.redis01.config;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

@Configuration
public class ObjectMapperConfig {

    private static final String PATTERN = "yyyy-MM-dd HH:mm:ss";

    @Bean(name = "myObjectMapper")
    public ObjectMapper objectMapper() {
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer());
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer());
        return new ObjectMapper()
                // 转换为格式化的json(控制台打印时，自动格式化规范)
                //.enable(SerializationFeature.INDENT_OUTPUT)
                // Include.ALWAYS  是序列化对像所有属性(默认)
                // Include.NON_NULL 只有不为null的字段才被序列化,属性为NULL 不序列化
                // Include.NON_EMPTY 如果为null或者 空字符串和空集合都不会被序列化
                // Include.NON_DEFAULT 属性为默认值不序列化
                .setSerializationInclusion(JsonInclude.Include.NON_NULL)
                // 如果是空对象的时候,不抛异常
                .configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false)
                // 反序列化的时候如果多了其他属性,不抛出异常
                .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
                // 取消时间的转化格式,默认是时间戳,可以取消,同时需要设置要表现的时间格式
                .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false)
                .setDateFormat(new SimpleDateFormat(PATTERN))
                // 对LocalDateTime序列化跟反序列化
                .registerModule(javaTimeModule)

                .setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY)
                // 此项必须配置，否则会报java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to XXX
                .enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL, JsonTypeInfo.As.PROPERTY)
                ;
    }

    static class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {
        @Override
        public void serialize(LocalDateTime value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
            gen.writeString(value.format(DateTimeFormatter.ofPattern(PATTERN)));
        }
    }

    static class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {
        @Override
        public LocalDateTime deserialize(JsonParser p, DeserializationContext deserializationContext) throws IOException {
            return LocalDateTime.parse(p.getValueAsString(), DateTimeFormatter.ofPattern(PATTERN));
        }
    }
}

package com.yzm.redis01.config;

import lombok.extern.slf4j.Slf4j;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.cache.interceptor.SimpleKey;

import java.lang.reflect.Method;
import java.util.Arrays;
/**
 * key生成器
 */
@Slf4j
public class MyKeyGenerator implements KeyGenerator {

    private static final String NO_PARAM = "[]";
    private static final String NULL_PARAM = "_";

    @Override
    public Object generate(Object target, Method method, Object... params) {
        StringBuilder key = new StringBuilder();
        key.append(target.getClass().getSimpleName()).append(".").append(method.getName()).append(":");

        if (params.length == 0) {
            return new SimpleKey(key.append(NO_PARAM).toString());
        }

        return new SimpleKey(key.append(Arrays.toString(params).replace("null", NULL_PARAM)).toString());
    }
}

package com.yzm.redis01.config;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.EnableCaching;
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.cache.RedisCacheWriter;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.*;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.StringRedisSerializer;

import javax.annotation.Resource;
import java.time.Duration;

@Configuration
@EnableCaching // 启动缓存
public class RedisConfig {

	@Bean(name = "myKeyGenerator")
    public MyKeyGenerator myKeyGenerator() {
        return new MyKeyGenerator();
    }

    @Resource(name = "myObjectMapper")
    private ObjectMapper objectMapper;

    /**
     * 选择redis作为默认缓存工具
     */
    @Bean
    public CacheManager cacheManager(RedisConnectionFactory connectionFactory) {
        RedisCacheWriter redisCacheWriter = RedisCacheWriter.nonLockingRedisCacheWriter(connectionFactory);
        RedisCacheConfiguration cacheConfiguration = RedisCacheConfiguration
                .defaultCacheConfig()
                // 默认缓存时间(秒)
                .entryTtl(Duration.ofSeconds(300L))
                // 序列化key、value
                .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer()))
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(jackson2JsonRedisSerializer()))
                // 禁用缓存空值
                .disableCachingNullValues();
        return new RedisCacheManager(redisCacheWriter, cacheConfiguration);
    }

    /**
     * redisTemplate配置
     */
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        // 配置连接工厂
        template.setConnectionFactory(factory);

        Jackson2JsonRedisSerializer<Object> jacksonSerializer = jackson2JsonRedisSerializer();
        StringRedisSerializer stringRedisSerializer = new StringRedisSerializer();

        // 使用StringRedisSerializer来序列化和反序列化redis的key,value采用json序列化
        template.setKeySerializer(stringRedisSerializer);
        template.setValueSerializer(jacksonSerializer);

        // 设置hash key 和value序列化模式
        template.setHashKeySerializer(stringRedisSerializer);
        template.setHashValueSerializer(jacksonSerializer);

        //支持事务
        template.setEnableTransactionSupport(true);
        template.afterPropertiesSet();

        return template;
    }

    private Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer() {
        //使用Jackson2JsonRedisSerializer来序列化和反序列化redis的value值（默认使用JDK的序列化方式）
        Jackson2JsonRedisSerializer<Object> jacksonSerializer = new Jackson2JsonRedisSerializer<>(Object.class);
        jacksonSerializer.setObjectMapper(objectMapper);
        return jacksonSerializer;
    }
}

3.功能实现

新增、更新、删除、查询数据时，对缓存执行对应相同的操作

package com.yzm.redis01.entity;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;

import java.io.Serializable;
import java.time.LocalDateTime;
import java.util.Date;

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Accessors(chain = true)
public class User implements Serializable {
    private static final long serialVersionUID = -2468903864827432779L;
    private Integer id;
    private String username;
    private String password;
    private Date createDate;
    private LocalDateTime updateDate;
}

package com.yzm.redis01.service;

import com.yzm.redis01.entity.User;

import java.util.List;

public interface UserService {

    User saveUser(User user);

    User updateUser(User user);

    int deleteUser(Integer id);

    void deleteAllCache();

    User getUserById(Integer id);

    List<User> selectAll();

	List<User> findAll(Object... params);
}

为了简便，数据不从数据库获取，这里是创建Map存储数据实现

package com.yzm.redis01.service.impl;

import com.yzm.redis01.entity.User;
import com.yzm.redis01.service.UserService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cache.annotation.CacheConfig;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.util.*;

@Slf4j
@Service
@CacheConfig(cacheNames = "users")
public class UserServiceImpl implements UserService {

    private static final Map<Integer, User> userMap;

    static {
        userMap = new HashMap<>();
        userMap.put(userMap.size() + 1, User.builder()
                .id(userMap.size() + 1).username("root").password("root").createDate(new Date()).updateDate(LocalDateTime.now()).build());
        userMap.put(userMap.size() + 1, User.builder()
                .id(userMap.size() + 1).username("admin").password("admin").createDate(new Date()).updateDate(LocalDateTime.now()).build());
    }

    @Override
    @CachePut(key = "#result.id", condition = "#result.id gt 0")
    public User saveUser(User user) {
        log.info("保存数据");
        int id = userMap.size() + 1;
        User build = User.builder()
                .id(id)
                .username(user.getUsername())
                .password(user.getPassword())
                .createDate(new Date())
                .updateDate(LocalDateTime.now())
                .build();
        userMap.put(id, build);
        return build;
    }

    @Override
    @CachePut(key = "#user.id", unless = "#result eq null")
    public User updateUser(User user) {
        log.info("更新数据");
        if (userMap.containsKey(user.getId())) {
            User update = userMap.get(user.getId());
            update.setUsername(user.getUsername())
                    .setPassword(user.getPassword())
                    .setUpdateDate(LocalDateTime.now());
            userMap.replace(user.getId(), update);
            return update;
        }
        return null;
    }

    @Override
    @CacheEvict(key = "#id", condition = "#result gt 0")
    public int deleteUser(Integer id) {
        log.info("删除数据");
        if (userMap.containsKey(id)) {
            userMap.remove(id);
            return 1;
        }
        return 0;
    }

    @Override
    @CacheEvict(allEntries = true)
    public void deleteAllCache() {
        log.info("清空缓存");
    }

    @Override
    @Cacheable(key = "#id", condition = "#id gt 1")
    public User getUserById(Integer id) {
        log.info("查询用户");
        return userMap.get(id);
    }

    @Override
    @Cacheable(key = "#root.methodName")
    public List<User> selectAll() {
        log.info("查询所有");
        return new ArrayList<>(userMap.values());
    }

    @Override
    @Cacheable(keyGenerator = "myKeyGenerator")
    public List<User> findAll(Object... params) {
        log.info("查询所有");
        return new ArrayList<>(userMap.values());
    }

}

package com.yzm.redis01.controller;

import com.yzm.redis01.entity.User;
import com.yzm.redis01.service.UserService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/user")
public class UserController {

    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping("/saveUser")
    public void saveUser() {
        User user = new User();
        user.setUsername("yzm");
        user.setPassword("yzm");
        System.out.println(userService.saveUser(user));
    }

    @GetMapping("/updateUser")
    public void updateUser(Integer id) {
        User user = new User();
        user.setId(id);
        user.setUsername("yzm");
        user.setPassword("123");
        System.out.println(userService.updateUser(user));
    }

    @GetMapping("/deleteUser")
    public void deleteUser(@RequestParam Integer id) {
        System.out.println(userService.deleteUser(id));
    }

    @GetMapping("/deleteAllCache")
    public void deleteAllCache() {
        userService.deleteAllCache();
    }

    @GetMapping("/getUserById")
    public void getUserById(@RequestParam Integer id) {
        System.out.println(userService.getUserById(id));
    }

    @GetMapping("/selectAll")
    public void selectAll() {
        List<User> users = userService.selectAll();
        users.forEach(System.out::println);
    }
}

4.缓存注解的使用说明

@CacheConfig：注解在类上，表示该类所有缓存方法使用统一指定的缓存区，也可以作用在方法上

@CacheAble：注解在方法上，应用到读数据的方法上，如查找方法：调用方法之前根据条件判断是否从缓存获取相应的数据，缓存没有数据，方法执行后添加到缓存

#id 直接使用参数名
#p0 p0对应参数列表的第一个参数，以此类推
#user.id 参数是对象时，使用对象属性
#root. 可以点出很多方法
#root.methodName
#result 返回值

http://localhost:8080/user/getUserById?id=1

http://localhost:8080/user/getUserById?id=2

http://localhost:8080/user/selectAll

@Cacheable运行流程：在调用方法之前判断condition，如果为true，则查缓存；没有缓存就调用方法并将数据添加到缓存；condition=false就与缓存无关了

@CachePut：注解在方法上，应用到写数据的方法上，如新增/修改方法，调用方法之后根据条件判断是否添加/更新相应的数据到缓存：

http://localhost:8080/user/saveUser

condition条件为true，添加到缓存，根据id查询直接从缓存获取
http://localhost:8080/user/getUserById?id=3

http://localhost:8080/user/updateUser?id=3
http://localhost:8080/user/getUserById?id=3

条件condition=true，执行缓存操作
条件unless=false，执行缓存操作；跟condition相反

@CacheEvict 注解在方法上，应用到删除数据的方法上，如删除方法，调用方法之后根据条件判断是否从缓存中移除相应的数据

http://localhost:8080/user/saveUser
http://localhost:8080/user/getUserById?id=3
http://localhost:8080/user/deleteUser?id=3

自定义缓存key自动生成器

    @Override
    @Cacheable(keyGenerator = "myKeyGenerator")
    public List<User> findAll(Object... params) {
        log.info("查询所有");
        return new ArrayList<>(userMap.values());
    }

@Slf4j
public class MyKeyGenerator implements KeyGenerator {

    private static final String NO_PARAM = "[]";
    private static final String NULL_PARAM = "_";

    @Override
    public Object generate(Object target, Method method, Object... params) {
        StringBuilder key = new StringBuilder();
        key.append(target.getClass().getSimpleName()).append(".").append(method.getName()).append(":");

        if (params.length == 0) {
            return new SimpleKey(key.append(NO_PARAM).toString());
        }

        return new SimpleKey(key.append(Arrays.toString(params).replace("null", NULL_PARAM)).toString());
    }
}

http://localhost:8080/user/findAll

http://localhost:8080/user/findAll?id=123

http://localhost:8080/user/findAll?username=yzm

@Caching
有时候我们可能组合多个Cache注解使用；比如用户新增成功后，我们要添加id–>user；username—>user；email—>user的缓存；
此时就需要@Caching组合多个注解标签了。

@Caching(
    put = {
        @CachePut(value = "users", key = "#user.id"),
        @CachePut(value = "users", key = "#user.username"),
        @CachePut(value = "users", key = "#user.email")
    }
)
public User save(User user) {}

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