1. Redisson
Redisson是Redis官方推荐的Java版的Redis客户端。它提供的功能非常多，也非常强大，此处我们只用它的分布式锁功能。
https://github.com/redisson/redisson
1.1. 基本用法
1
1.2. Distributed locks and synchronizers
RedissonClient中提供了好多种锁，还有其它很多实用的方法
1.2.1. Lock
默认，非公平锁
最简洁的一种方法
指定超时时间
异步
1.2.2 Fair Lock
1.2.3 MultiLock
1.2.4 RedLock
1.3. 示例
pom.xml
1
2 xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
3 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
4
application.yml
1 server:
2 port: 8080
3 spring:
4 application:
5 name: cjs-redisson-example
6 redis:
7 cluster:
8 nodes: 10.0.29.30:6379, 10.0.29.95:6379, 10.0.29.205:6379
9 lettuce:
10 pool:
11 min-idle: 0
12 max-idle: 8
13 max-active: 20
14 datasource:
15 url: jdbc:mysql://127.0.0.1:3306/test
16 username: root
17 password: 123456
18 driver-class-name: com.mysql.cj.jdbc.Driver
19 type: com.zaxxer.hikari.HikariDataSource
RedissonConfig.java
1 package com.cjs.example.lock.config;
2
3 import org.redisson.Redisson;
4 import org.redisson.api.RedissonClient;
5 import org.redisson.config.Config;
6 import org.springframework.context.annotation.Bean;
7 import org.springframework.context.annotation.Configuration;
8
9 /**
10 * @author ChengJianSheng
11 * @date 2019-07-26
12 */
13 @Configuration
14 public class RedissonConfig {
15
16 @Bean
17 public RedissonClient redissonClient() {
18 Config config = new Config();
19 config.useClusterServers()
20 .setScanInterval(2000)
21 .addNodeAddress("redis://10.0.29.30:6379", "redis://10.0.29.95:6379")
22 .addNodeAddress("redis://10.0.29.205:6379");
23
24 RedissonClient redisson = Redisson.create(config);
25
26 return redisson;
27 }
28
29 }
CourseServiceImpl.java
1 package com.cjs.example.lock.service.impl;
2
3 import com.alibaba.fastjson.JSON;
4 import com.cjs.example.lock.constant.RedisKeyPrefixConstant;
5 import com.cjs.example.lock.model.CourseModel;
6 import com.cjs.example.lock.model.CourseRecordModel;
7 import com.cjs.example.lock.repository.CourseRecordRepository;
8 import com.cjs.example.lock.repository.CourseRepository;
9 import com.cjs.example.lock.service.CourseService;
10 import lombok.extern.slf4j.Slf4j;
11 import org.apache.commons.lang3.StringUtils;
12 import org.redisson.api.RLock;
13 import org.redisson.api.RedissonClient;
14 import org.springframework.beans.factory.annotation.Autowired;
15 import org.springframework.data.redis.core.HashOperations;
16 import org.springframework.data.redis.core.StringRedisTemplate;
17 import org.springframework.stereotype.Service;
18
19 import java.util.concurrent.TimeUnit;
20
21 /**
22 * @author ChengJianSheng
23 * @date 2019-07-26
24 */
25 @Slf4j
26 @Service
27 public class CourseServiceImpl implements CourseService {
28
29 @Autowired
30 private CourseRepository courseRepository;
31 @Autowired
32 private CourseRecordRepository courseRecordRepository;
33 @Autowired
34 private StringRedisTemplate stringRedisTemplate;
35 @Autowired
36 private RedissonClient redissonClient;
37
38 @Override
39 public CourseModel getById(Integer courseId) {
40
41 CourseModel courseModel = null;
42
43 HashOperations<String, String, String> hashOperations = stringRedisTemplate.opsForHash();
44
45 String value = hashOperations.get(RedisKeyPrefixConstant.COURSE, String.valueOf(courseId));
46
47 if (StringUtils.isBlank(value)) {
48 String lockKey = RedisKeyPrefixConstant.LOCK_COURSE + courseId;
49 RLock lock = redissonClient.getLock(lockKey);
50 try {
51 boolean res = lock.tryLock(10, TimeUnit.SECONDS);
52 if (res) {
53 value = hashOperations.get(RedisKeyPrefixConstant.COURSE, String.valueOf(courseId));
54 if (StringUtils.isBlank(value)) {
55 log.info("从数据库中读取");
56 courseModel = courseRepository.findById(courseId).orElse(null);
57 hashOperations.put(RedisKeyPrefixConstant.COURSE, String.valueOf(courseId), JSON.toJSONString(courseModel));
58 }
59 }
60 } catch (InterruptedException e) {
61 e.printStackTrace();
62 } finally {
63 lock.unlock();
64 }
65 } else {
66 log.info("从缓存中读取");
67 courseModel = JSON.parseObject(value, CourseModel.class);
68 }
69
70 return courseModel;
71 }
72
73 @Override
74 public void upload(Integer userId, Integer courseId, Integer studyProcess) {
75
76 HashOperations<String, String, String> hashOperations = stringRedisTemplate.opsForHash();
77
78 String cacheKey = RedisKeyPrefixConstant.COURSE_PROGRESS + ":" + userId;
79 String cacheValue = hashOperations.get(cacheKey, String.valueOf(courseId));
80 if (StringUtils.isNotBlank(cacheValue) && studyProcess <= Integer.valueOf(cacheValue)) {
81 return;
82 }
83
84 String lockKey = "upload:" + userId + ":" + courseId;
85
86 RLock lock = redissonClient.getLock(lockKey);
87
88 try {
89 lock.lock(10, TimeUnit.SECONDS);
90
91 cacheValue = hashOperations.get(cacheKey, String.valueOf(courseId));
92 if (StringUtils.isBlank(cacheValue) || studyProcess > Integer.valueOf(cacheValue)) {
93 CourseRecordModel model = new CourseRecordModel();
94 model.setUserId(userId);
95 model.setCourseId(courseId);
96 model.setStudyProcess(studyProcess);
97 courseRecordRepository.save(model);
98 hashOperations.put(cacheKey, String.valueOf(courseId), String.valueOf(studyProcess));
99 }
100
101 } catch (Exception ex) {
102 log.error("获取所超时！", ex);
103 } finally {
104 lock.unlock();
105 }
106
107 }
108 }
StockServiceImpl.java
1 package com.cjs.example.lock.service.impl;
2
3 import com.cjs.example.lock.constant.RedisKeyPrefixConstant;
4 import com.cjs.example.lock.service.StockService;
5 import org.apache.commons.lang3.StringUtils;
6 import org.springframework.beans.factory.annotation.Autowired;
7 import org.springframework.data.redis.core.HashOperations;
8 import org.springframework.data.redis.core.StringRedisTemplate;
9 import org.springframework.stereotype.Service;
10
11 /**
12 * @author ChengJianSheng
13 * @date 2019-07-26
14 */
15 @Service
16 public class StockServiceImpl implements StockService {
17
18 @Autowired
19 private StringRedisTemplate stringRedisTemplate;
20
21 @Override
22 public int getByProduct(Integer productId) {
23 HashOperations<String, String, String> hashOperations = stringRedisTemplate.opsForHash();
24 String value = hashOperations.get(RedisKeyPrefixConstant.STOCK, String.valueOf(productId));
25 if (StringUtils.isBlank(value)) {
26 return 0;
27 }
28 return Integer.valueOf(value);
29 }
30
31 @Override
32 public boolean decrease(Integer productId) {
33 int stock = getByProduct(productId);
34 if (stock <= 0) {
35 return false;
36 }
37 HashOperations<String, String, String> hashOperations = stringRedisTemplate.opsForHash();
38 hashOperations.put(RedisKeyPrefixConstant.STOCK, String.valueOf(productId), String.valueOf(stock - 1));
39 return true;
40 }
41 }
OrderServiceImpl.java
1 package com.cjs.example.lock.service.impl;
2
3 import com.cjs.example.lock.model.OrderModel;
4 import com.cjs.example.lock.repository.OrderRepository;
5 import com.cjs.example.lock.service.OrderService;
6 import com.cjs.example.lock.service.StockService;
7 import lombok.extern.slf4j.Slf4j;
8 import org.redisson.api.RLock;
9 import org.redisson.api.RedissonClient;
10 import org.springframework.beans.factory.annotation.Autowired;
11 import org.springframework.stereotype.Service;
12
13 import java.util.Date;
14 import java.util.UUID;
15 import java.util.concurrent.TimeUnit;
16
17 /**
18 * @author ChengJianSheng
19 * @date 2019-07-30
20 */
21 @Slf4j
22 @Service
23 public class OrderServiceImpl implements OrderService {
24
25 @Autowired
26 private StockService stockService;
27 @Autowired
28 private OrderRepository orderRepository;
29 @Autowired
30 private RedissonClient redissonClient;
31
32 /**
33 * 乐观锁
34 */
35 @Override
36 public String save(Integer userId, Integer productId) {
37 int stock = stockService.getByProduct(productId);
38 log.info("剩余库存：{}", stock);
39 if (stock <= 0) {
40 return null;
41 }
42
43 // 如果不加锁，必然超卖
44
45 RLock lock = redissonClient.getLock("stock:" + productId);
46
47 try {
48 lock.lock(10, TimeUnit.SECONDS);
49
50 String orderNo = UUID.randomUUID().toString().replace("-", "").toUpperCase();
51
52 if (stockService.decrease(productId)) {
53
54 OrderModel orderModel = new OrderModel();
55 orderModel.setUserId(userId);
56 orderModel.setProductId(productId);
57 orderModel.setOrderNo(orderNo);
58 Date now = new Date();
59 orderModel.setCreateTime(now);
60 orderModel.setUpdateTime(now);
61 orderRepository.save(orderModel);
62
63 return orderNo;
64 }
65
66 } catch (Exception ex) {
67 log.error("下单失败", ex);
68 } finally {
69 lock.unlock();
70 }
71
72 return null;
73 }
74
75 }
OrderModel.java
1 package com.cjs.example.lock.model;
2
3 import lombok.Data;
4
5 import javax.persistence.*;
6 import java.io.Serializable;
7 import java.util.Date;
8
9 /**
10 * @author ChengJianSheng
11 * @date 2019-07-30
12 */
13 @Data
14 @Entity
15 @Table(name = "t_order")
16 public class OrderModel implements Serializable {
17
18 @Id
19 @GeneratedValue(strategy = GenerationType.IDENTITY)
20 private Integer id;
21
22 @Column(name = "order_no")
23 private String orderNo;
24
25 @Column(name = "product_id")
26 private Integer productId;
27
28 @Column(name = "user_id")
29 private Integer userId;
30
31 @Column(name = "create_time")
32 private Date createTime;
33
34 @Column(name = "update_time")
35 private Date updateTime;
36 }
数据库脚本.sql
1 SET NAMES utf8mb4;
2 SET FOREIGN_KEY_CHECKS = 0;
3
4 -- ----------------------------
5 -- Table structure for t_course
6 -- ----------------------------
7 DROP TABLE IF EXISTS `t_course`;
8 CREATE TABLE `t_course` (
9 `id` int(11) NOT NULL AUTO_INCREMENT,
10 `course_name` varchar(64) NOT NULL,
11 `course_type` tinyint(4) NOT NULL DEFAULT '1',
12 `start_time` datetime NOT NULL,
13 PRIMARY KEY (`id`)
14 ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4;
15
16 -- ----------------------------
17 -- Table structure for t_order
18 -- ----------------------------
19 DROP TABLE IF EXISTS `t_order`;
20 CREATE TABLE `t_order` (
21 `id` int(11) NOT NULL AUTO_INCREMENT,
22 `order_no` varchar(256) CHARACTER SET latin1 NOT NULL,
23 `user_id` int(11) NOT NULL,
24 `product_id` int(11) NOT NULL,
25 `create_time` datetime NOT NULL,
26 `update_time` datetime DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
27 PRIMARY KEY (`id`)
28 ) ENGINE=InnoDB AUTO_INCREMENT=109 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
29
30 -- ----------------------------
31 -- Table structure for t_user_course_record
32 -- ----------------------------
33 DROP TABLE IF EXISTS `t_user_course_record`;
34 CREATE TABLE `t_user_course_record` (
35 `id` int(11) NOT NULL AUTO_INCREMENT,
36 `user_id` int(11) NOT NULL,
37 `course_id` int(11) NOT NULL,
38 `study_process` int(11) NOT NULL,
39 PRIMARY KEY (`id`)
40 ) ENGINE=InnoDB AUTO_INCREMENT=103 DEFAULT CHARSET=utf8mb4;
41
42 SET FOREIGN_KEY_CHECKS = 1;
1.4 工程结构
https://github.com/chengjiansheng/cjs-redisson-example
1.5 Redis集群创建
1.6 测试
测试/course/upload
测试/order/create
2. Spring Integration
用法与Redisson类似
1
1 package com.kaishustory.base.conf;
2
3 import org.springframework.context.annotation.Bean;
4 import org.springframework.context.annotation.Configuration;
5 import org.springframework.data.redis.connection.RedisConnectionFactory;
6 import org.springframework.integration.redis.util.RedisLockRegistry;
7
8 /**
9 * @author ChengJianSheng
10 * @date 2019-07-30
11 */
12 @Configuration
13 public class RedisLockConfig {
14
15 @Bean
16 public RedisLockRegistry redisLockRegistry(RedisConnectionFactory redisConnectionFactory) {
17 return new RedisLockRegistry(redisConnectionFactory, "asdf")
18 }
19
20 }
1 @Autowired
2 private RedisLockRegistry redisLockRegistry;
3
4 public void save(Integer userId) {
5
6 String lockKey = "order:" + userId;
7
8 Lock lock = redisLockRegistry.obtain(lockKey);
9 try {
10 lock.lock();
11
12 //todo
13
14 } finally {
15 lock.unlock();
16 }
17
18 }
3. 其它
https://github.com/redisson/redisson/wiki/8.-Distributed-locks-and-synchronizers
https://www.cnblogs.com/cjsblog/p/9831423.html