Shulou(Shulou.com)05/31 Report--

I believe many inexperienced people are at a loss about how to use Redis to like and cancel likes in Spring Cloud. Therefore, this article summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

1. Design and implementation of Redis cache

1.1 Redis installation and operation

Please refer to the relevant tutorials for Redis installation.

Talk about Docker installation and run Redis

Docker run-d-p 6379 6379 redis:4.0.8

If Redis is already installed, open the command line and enter the command to start Redis

Redis-server

1.2 Integration of Redis and SpringBoot projects

1. Introducing dependencies into pom.xml

Org.springframework.boot spring-boot-starter-data-redis

two。 Add a comment @ EnableCaching to the startup class

@ SpringBootApplication @ EnableDiscoveryClient @ EnableSwagger2 @ EnableFeignClients (basePackages = "com.solo.coderiver.project.client") @ EnableCaching publicclass UserApplication {public static void main (String [] args) {SpringApplication.run (UserApplication.class, args);}}

3. Write the Redis configuration class RedisConfig

Import com.fasterxml.jackson.annotation.JsonAutoDetect; import com.fasterxml.jackson.annotation.PropertyAccessor; import com.fasterxml.jackson.databind.ObjectMapper; import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.data.redis.connection.RedisConnectionFactory; import org.springframework.data.redis.core.RedisTemplate; import org.springframework.data.redis.core.StringRedisTemplate; import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer Import java.net.UnknownHostException; @ Configuration publicclass RedisConfig {@ Bean @ ConditionalOnMissingBean (name = "redisTemplate") public RedisTemplate redisTemplate (RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer (Object.class); ObjectMapper om = new ObjectMapper (); om.setVisibility (PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY); om.enableDefaultTyping (ObjectMapper.DefaultTyping.NON_FINAL) Jackson2JsonRedisSerializer.setObjectMapper (om); RedisTemplate template = new RedisTemplate (); template.setConnectionFactory (redisConnectionFactory); template.setKeySerializer (jackson2JsonRedisSerializer); template.setValueSerializer (jackson2JsonRedisSerializer); template.setHashKeySerializer (jackson2JsonRedisSerializer); template.setHashValueSerializer (jackson2JsonRedisSerializer); template.afterPropertiesSet (); return template } @ Bean @ ConditionalOnMissingBean (StringRedisTemplate.class) public StringRedisTemplate stringRedisTemplate (RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {StringRedisTemplate template = new StringRedisTemplate (); template.setConnectionFactory (redisConnectionFactory); return template;}}

At this point, the configuration of Redis in the SpringBoot project is complete, and you can use it happily.

1.3 data structure types of Redis

Redis can store the mapping between keys and five different types of data structures, namely String (string), List (list), Set (collection), Hash (hash), and Zset (ordered set).

Here is a brief introduction to these five types of data structures:

1.4 Storage format of like data in Redis

Use Redis to store two kinds of data, one is to record the status of likes, likes, and likes, and the other is to make a simple count of how many times each user has been liked.

Due to the need to record likes and likes, as well as the like status (like and cancel likes), and to take out all the like data in Redis at regular intervals, it is analyzed that Hash is the most appropriate Redis data format.

Because the data in Hash is stored in a key, you can easily take out all the like data through this key. The data in this key can also be stored in the form of key-value pairs, which is convenient for people to be liked, liked and liked.

Set the admirable id as likedPostId, the id of the liked person as likedUserId, the status of likes as 1, and the status of canceling likes as 0. Id and id are used as keys, the two id are separated by::, and the like status is used as the value.

So if the user likes it, the stored key is: likedUserId::likedPostId, and the corresponding value is 1. To cancel giving likes, the key stored is: likedUserId::likedPostId, and the corresponding value is 0. When fetching data, use the key:: cut to get two id, which is also very convenient.

What you see in the visualization tool RDM is like this.

1.5 Operation Redis

The specific operation method is encapsulated in the RedisService interface.

RedisService.java

Import com.solo.coderiver.user.dataobject.UserLike; import com.solo.coderiver.user.dto.LikedCountDTO; import java.util.List; publicinterface RedisService {/ * like. The status is 1 * @ param likedUserId * @ param likedPostId * / void saveLiked2Redis (String likedUserId, String likedPostId); / * cancel likes. Change the status to 0 * @ param likedUserId * @ param likedPostId * / void unlikeFromRedis (String likedUserId, String likedPostId); / * Delete a like data from Redis * @ param likedUserId * @ param likedPostId * / void deleteLikedFromRedis (String likedUserId, String likedPostId) / * * the number of likes given by this user is added by 1 * @ param likedUserId * / void incrementLikedCount (String likedUserId); the number of likes by this user is reduced by 1 * @ param likedUserId * / void decrementLikedCount (String likedUserId) / * get all the like data stored in Redis * @ return * / List getLikedDataFromRedis (); / * get all the likes stored in Redis * @ return * / List getLikedCountFromRedis ();}

Implementation class RedisServiceImpl.java

Import com.solo.coderiver.user.dataobject.UserLike; import com.solo.coderiver.user.dto.LikedCountDTO; import com.solo.coderiver.user.enums.LikedStatusEnum; import com.solo.coderiver.user.service.LikedService; import com.solo.coderiver.user.service.RedisService; import com.solo.coderiver.user.utils.RedisKeyUtils; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.redis.core.Cursor Import org.springframework.data.redis.core.RedisTemplate; import org.springframework.data.redis.core.ScanOptions; import org.springframework.stereotype.Service; import java.util.ArrayList; import java.util.List; import java.util.Map; @ Service @ Slf4j publicclass RedisServiceImpl implements RedisService {@ Autowired RedisTemplate redisTemplate; @ Autowired LikedService likedService; @ Override public void saveLiked2Redis (String likedUserId, String likedPostId) {String key = RedisKeyUtils.getLikedKey (likedUserId, likedPostId) RedisTemplate.opsForHash () .put (RedisKeyUtils.MAP_KEY_USER_LIKED, key, LikedStatusEnum.LIKE.getCode ());} @ Override public void unlikeFromRedis (String likedUserId, String likedPostId) {String key = RedisKeyUtils.getLikedKey (likedUserId, likedPostId); redisTemplate.opsForHash () .put (RedisKeyUtils.MAP_KEY_USER_LIKED, key, LikedStatusEnum.UNLIKE.getCode ()) } @ Override public void deleteLikedFromRedis (String likedUserId, String likedPostId) {String key = RedisKeyUtils.getLikedKey (likedUserId, likedPostId); redisTemplate.opsForHash () .delete (RedisKeyUtils.MAP_KEY_USER_LIKED, key);} @ Override public void incrementLikedCount (String likedUserId) {redisTemplate.opsForHash () .increment (RedisKeyUtils.MAP_KEY_USER_LIKED_COUNT, likedUserId, 1) } @ Override public void decrementLikedCount (String likedUserId) {redisTemplate.opsForHash () .increment (RedisKeyUtils.MAP_KEY_USER_LIKED_COUNT, likedUserId,-1);} @ Override public List getLikedDataFromRedis () {Cursor cursor = redisTemplate.opsForHash () .scan (RedisKeyUtils.MAP_KEY_USER_LIKED, ScanOptions.NONE); List list = new ArrayList () While (cursor.hasNext ()) {Map.Entry entry = cursor.next (); String key = (String) entry.getKey (); / / isolate likedUserId,likedPostId String [] split = key.split ("::"); String likedUserId = split [0]; String likedPostId = split [1] Integer value = (Integer) entry.getValue (); / / assembled into a UserLike object UserLike userLike = new UserLike (likedUserId, likedPostId, value); list.add (userLike); / / remove redisTemplate.opsForHash (). Delete (RedisKeyUtils.MAP_KEY_USER_LIKED, key) from Redis after saving to list;} return list } @ Override public List getLikedCountFromRedis () {Cursor cursor = redisTemplate.opsForHash () .scan (RedisKeyUtils.MAP_KEY_USER_LIKED_COUNT, ScanOptions.NONE); List list = new ArrayList (); while (cursor.hasNext ()) {Map.Entry map = cursor.next (); / / store the number of likes in LikedCountDT String key = (String) map.getKey () LikedCountDTO dto = new LikedCountDTO (key, (Integer) map.getValue ()); list.add (dto); / / delete this record from Redis redisTemplate.opsForHash () .delete (RedisKeyUtils.MAP_KEY_USER_LIKED_COUNT, key);} return list;}}

Tool classes and enumeration classes used

RedisKeyUtils, used to generate key according to certain rules

Publicclass RedisKeyUtils {/ / key publicstaticfinal String MAP_KEY_USER_LIKED that saves the data of users' likes = "MAP_USER_LIKED"; / / saves the number of users' likes key publicstaticfinal String MAP_KEY_USER_LIKED_COUNT = "MAP_USER_LIKED_COUNT"; / * splices the id of the users who are liked and the id of the people who like them as key. Format 222222 param likedPostId id * @ return * / public static String getLikedKey (String likedUserId, String likedPostId) {StringBuilder builder = new StringBuilder (); builder.append (likedUserId); builder.append ("::"); builder.append (likedPostId); return builder.toString ();}}

Enumerated class of LikedStatusEnum users' like status

Package com.solo.coderiver.user.enums; import lombok.Getter; / * status of users' likes * / @ Getter publicenum LikedStatusEnum {LIKE (1, "like"), UNLIKE (0, "cancel likes / no likes"),; private Integer code; private String msg; LikedStatusEnum (Integer code, String msg) {this.code = code; this.msg = msg }}

II. Database design

The database table must contain at least three fields: like user id, like user id, and like status. Plus the primary key id, creation time, modification time on the line.

Construction table sentence

Create table `status` (`id` int not null auto_increment, `liked_user_ id` varchar (32) not null comment 'id', `liked_post_ id` varchar (32) not null comment' like user id', `status`tinyint (1) default'1' comment 'like status, 0 cancel 1 like', 'create_ time` timestamp not nulldefault current_timestamp comment' creation time', `update_ time` timestamp not nulldefault current_timestamp on update current_timestamp comment 'modification time', primary key (`id`), INDEX `liked_post_ id` (`liked_user_ id`), INDEX `liked_post_ id` (`liked_post_ id`) comment 'user praise form'

Corresponding object UserLike

Import com.solo.coderiver.user.enums.LikedStatusEnum; import lombok.Data; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; / * user praise form * / @ Entity @ Data publicclass UserLike {/ / Primary key id @ Id @ GeneratedValue (strategy = GenerationType.IDENTITY) private Integer id; / / id private String likedUserId of the user being liked / / the id private String likedPostId; / / like status of the like user. Private Integer status = LikedStatusEnum.UNLIKE.getCode (); public UserLike () {} public UserLike (String likedUserId, String likedPostId, Integer status) {this.likedUserId = likedUserId; this.likedPostId = likedPostId; this.status = status;}} by default

III. Database operation

The operation database is also encapsulated in the interface

LikedService

Import com.solo.coderiver.user.dataobject.UserLike; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import java.util.List; publicinterface LikedService {/ * Save like record * @ param userLike * @ return * / UserLike save (UserLike userLike) / * batch save or modify * @ param list * / List saveAll (List list); / * query the like list based on the id of the person being liked (that is, query who has liked that person) * @ param likedUserId's id * @ param pageable * @ return * / Page getLikedListByLikedUserId (String likedUserId, Pageable pageable) / * query the like list based on the like person's id (that is, query who the person has liked) * @ param likedPostId * @ param pageable * @ return * / Page getLikedListByLikedPostId (String likedPostId, Pageable pageable) / * query whether there is a like record * @ param likedUserId * @ param likedPostId * @ return * / UserLike getByLikedUserIdAndLikedPostId (String likedUserId, String likedPostId) through the likes and likes id; / * store the like data in Redis in the database * / void transLikedFromRedis2DB () / * store the number of likes in Redis into the database * / void transLikedCountFromRedis2DB ();}

LikedServiceImpl implementation class

Import com.solo.coderiver.user.dataobject.UserInfo; import com.solo.coderiver.user.dataobject.UserLike; import com.solo.coderiver.user.dto.LikedCountDTO; import com.solo.coderiver.user.enums.LikedStatusEnum; import com.solo.coderiver.user.repository.UserLikeRepository; import com.solo.coderiver.user.service.LikedService; import com.solo.coderiver.user.service.RedisService; import com.solo.coderiver.user.service.UserService; import lombok.extern.slf4j.Slf4j Import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import java.util.List; @ Service @ Slf4j publicclass LikedServiceImpl implements LikedService {@ Autowired UserLikeRepository likeRepository; @ Autowired RedisService redisService; @ Autowired UserService userService @ Override @ Transactional public UserLike save (UserLike userLike) {return likeRepository.save (userLike);} @ Override @ Transactional public List saveAll (List list) {return likeRepository.saveAll (list);} @ Override public Page getLikedListByLikedUserId (String likedUserId, Pageable pageable) {return likeRepository.findByLikedUserIdAndStatus (likedUserId, LikedStatusEnum.LIKE.getCode (), pageable) } @ Override public Page getLikedListByLikedPostId (String likedPostId, Pageable pageable) {return likeRepository.findByLikedPostIdAndStatus (likedPostId, LikedStatusEnum.LIKE.getCode (), pageable);} @ Override public UserLike getByLikedUserIdAndLikedPostId (String likedUserId, String likedPostId) {return likeRepository.findByLikedUserIdAndLikedPostId (likedUserId, likedPostId);} @ Override @ Transactional public void transLikedFromRedis2DB () {List list = redisService.getLikedDataFromRedis () For (UserLike like: list) {UserLike ul = getByLikedUserIdAndLikedPostId (like.getLikedUserId (), like.getLikedPostId ()); if (ul = = null) {/ / No record, directly stored in save (like) } else {/ / has a record and needs to update ul.setStatus (like.getStatus ()); save (ul);} @ Override @ Transactional public void transLikedCountFromRedis2DB () {List list = redisService.getLikedCountFromRedis () For (LikedCountDTO dto: list) {UserInfo user = userService.findById (dto.getId ()); / / the number of likes is an operation that doesn't matter. There is no need to throw an exception if (user! = null) {Integer likeNum = user.getLikeNum () + dto.getCount (); user.setLikeNum (likeNum) / / update the number of likes userService.updateInfo (user);}}

These are the operations of the database, mainly adding, deleting, changing and checking.

4. Enable timed tasks to be persisted and stored in the database

Timed task Quartz is very powerful, so use it.

Steps for using Quartz:

1. Add dependency

Org.springframework.boot spring-boot-starter-quartz

two。 Write a configuration file

Package com.solo.coderiver.user.config; import com.solo.coderiver.user.task.LikeTask; import org.quartz.*; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @ Configuration publicclass QuartzConfig {privatestaticfinal String LIKE_TASK_IDENTITY = "LikeTaskQuartz"; @ Bean public JobDetail quartzDetail () {return JobBuilder.newJob (LikeTask.class) .withIdentity (LIKE_TASK_IDENTITY) .storeDurably () .build () } @ Bean public Trigger quartzTrigger () {SimpleScheduleBuilder scheduleBuilder = SimpleScheduleBuilder.simpleSchedule () / / .withIntervalInSeconds (10) / set the time period in seconds. WithIntervalInHours (2) / / execute .repeatForever () every two hours. Return TriggerBuilder.newTrigger () .forJob (quartzDetail ()) .withIdentity (LIKE_TASK_IDENTITY) .withschedule (scheduleBuilder) .build ();}}

3. Classes that write and execute tasks inherit from QuartzJobBean

Package com.solo.coderiver.user.task; import com.solo.coderiver.user.service.LikedService; import lombok.extern.slf4j.Slf4j; import org.apache.commons.lang.time.DateUtils; import org.quartz.JobExecutionContext; import org.quartz.JobExecutionException; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.scheduling.quartz.QuartzJobBean; import java.text.SimpleDateFormat; import java.util.Date / * scheduled tasks for likes * / @ Slf4j publicclass LikeTask extends QuartzJobBean {@ Autowired LikedService likedService; private SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss"); @ Override protected void executeInternal (JobExecutionContext jobExecutionContext) throws JobExecutionException {log.info ("LikeTask- {}", sdf.format (new Date () / / synchronize the like information in Redis to the database likedService.transLikedFromRedis2DB (); likedService.transLikedCountFromRedis2DB ();}}

The method encapsulated by LikedService is directly called in the scheduled task to complete data synchronization.

After reading the above, have you mastered how to use Redis to achieve likes and cancel likes in Spring Cloud? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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