SpringBoot實現(xiàn)抽獎大轉盤

1、項目介紹

這是一個基于Spring boot + Mybatis Plus + Redis 的簡單案例。

主要是將活動內(nèi)容、獎品信息、記錄信息等緩存到Redis中，然后所有的抽獎過程全部從Redis中做數(shù)據(jù)的操作。

大致內(nèi)容很簡單，具體操作下面慢慢分析。

2、項目演示

話不多說，首先上圖看看項目效果，如果覺得還行的話咱們就來看看他具體是怎么實現(xiàn)的。

3、表結構

該項目包含以下四張表，分別是活動表、獎項表、獎品表以及中獎記錄表。具體的SQL會在文末給出。

4、項目搭建

咱們首先先搭建一個標準的Spring boot 項目，直接IDEA創(chuàng)建，然后選擇一些相關的依賴即可。

4.1 依賴

該項目主要用到了：Redis，thymeleaf，mybatis-plus等依賴。

????
????????org.springframework.boot
????????spring-boot-starter-data-redis
????

????
????????org.springframework.boot
????????spring-boot-starter-thymeleaf
????

????
????????org.springframework.boot
????????spring-boot-starter-web
????

????
????????mysql
????????mysql-connector-java
????????runtime
????

????
????????org.springframework.boot
????????spring-boot-starter-test
????????test
????

????
????????com.baomidou
????????mybatis-plus-boot-starter
????????3.4.3
????

????
????????com.baomidou
????????mybatis-plus-generator
????????3.4.1
????

????
????????com.alibaba
????????fastjson
????????1.2.72
????

????
????????com.alibaba
????????druid-spring-boot-starter
????????1.1.22
????

????
????????org.apache.commons
????????commons-lang3
????????3.9
????

????
????????org.projectlombok
????????lombok
????????1.18.12
????

????
????????org.apache.commons
????????commons-pool2
????????2.8.0
????

????
????????org.mapstruct
????????mapstruct
????????1.4.2.Final
????

????
????????org.mapstruct
????????mapstruct-jdk8
????????1.4.2.Final
????

????
????????org.mapstruct
????????mapstruct-processor
????????1.4.2.Final
????

????
????????joda-time
????????joda-time
????????2.10.6
????

4.2 YML配置

依賴引入之后，我們需要進行相應的配置：數(shù)據(jù)庫連接信息、Redis、mybatis-plus、線程池等。

server:
??port:?8080
??servlet:
????context-path:?/
spring:
??datasource:
????druid:
??????url:?jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false
??????username:?root
??????password:?123456
??????driver-class-name:?com.mysql.cj.jdbc.Driver
??????initial-size:?30
??????max-active:?100
??????min-idle:?10
??????max-wait:?60000
??????time-between-eviction-runs-millis:?60000
??????min-evictable-idle-time-millis:?300000
??????validation-query:?SELECT?1?FROM?DUAL
??????test-while-idle:?true
??????test-on-borrow:?false
??????test-on-return:?false
??????filters:?stat,wall
??redis:
????port:?6379
????host:?127.0.0.1
????lettuce:
??????pool:
????????max-active:?-1
????????max-idle:?2000
????????max-wait:?-1
????????min-idle:?1
????????time-between-eviction-runs:?5000
??mvc:
????view:
??????prefix:?classpath:/templates/
??????suffix:?.html
#?mybatis-plus
mybatis-plus:
??configuration:
????map-underscore-to-camel-case:?true
????auto-mapping-behavior:?full
??mapper-locations:?classpath*:mapper/**/*Mapper.xml

#?線程池
async:
??executor:
????thread:
??????core-pool-size:?6
??????max-pool-size:?12
??????queue-capacity:?100000
??????name-prefix:?lottery-service-

4.3 代碼生成

這邊我們可以直接使用mybatis-plus的代碼生成器幫助我們生成一些基礎的業(yè)務代碼，避免這些重復的體力活。

這邊貼出相關代碼，直接修改數(shù)據(jù)庫連接信息、相關包名模塊名即可。

public?class?MybatisPlusGeneratorConfig?{
????public?static?void?main(String[]?args)?{
????????//?代碼生成器
????????AutoGenerator?mpg?=?new?AutoGenerator();

????????//?全局配置
????????GlobalConfig?gc?=?new?GlobalConfig();
????????String?projectPath?=?System.getProperty("user.dir");
????????gc.setOutputDir(projectPath?+?"/src/main/java");
????????gc.setAuthor("chen");
????????gc.setOpen(false);
????????//實體屬性?Swagger2?注解
????????gc.setSwagger2(false);
????????mpg.setGlobalConfig(gc);

????????//?數(shù)據(jù)源配置
????????DataSourceConfig?dsc?=?new?DataSourceConfig();
????????dsc.setUrl("jdbc:mysql://127.0.0.1:3306/test?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
????????dsc.setDriverName("com.mysql.cj.jdbc.Driver");
????????dsc.setUsername("root");
????????dsc.setPassword("123456");
????????mpg.setDataSource(dsc);

????????//?包配置
????????PackageConfig?pc?=?new?PackageConfig();
//????????pc.setModuleName(scanner("模塊名"));
????????pc.setParent("com.example.lottery");
????????pc.setEntity("dal.model");
????????pc.setMapper("dal.mapper");
????????pc.setService("service");
????????pc.setServiceImpl("service.impl");
????????mpg.setPackageInfo(pc);


????????//?配置模板
????????TemplateConfig?templateConfig?=?new?TemplateConfig();

????????templateConfig.setXml(null);
????????mpg.setTemplate(templateConfig);

????????//?策略配置
????????StrategyConfig?strategy?=?new?StrategyConfig();
????????strategy.setNaming(NamingStrategy.underline_to_camel);
????????strategy.setColumnNaming(NamingStrategy.underline_to_camel);
????????strategy.setSuperEntityClass("com.baomidou.mybatisplus.extension.activerecord.Model");
????????strategy.setEntityLombokModel(true);
????????strategy.setRestControllerStyle(true);

????????strategy.setEntityLombokModel(true);
????????//?公共父類
//????????strategy.setSuperControllerClass("com.baomidou.ant.common.BaseController");
????????//?寫于父類中的公共字段
//????????strategy.setSuperEntityColumns("id");
????????strategy.setInclude(scanner("lottery,lottery_item,lottery_prize,lottery_record").split(","));
????????strategy.setControllerMappingHyphenStyle(true);
????????strategy.setTablePrefix(pc.getModuleName()?+?"_");
????????mpg.setStrategy(strategy);
????????mpg.setTemplateEngine(new?FreemarkerTemplateEngine());
????????mpg.execute();
????}

????public?static?String?scanner(String?tip)?{
????????Scanner?scanner?=?new?Scanner(System.in);
????????StringBuilder?help?=?new?StringBuilder();
????????help.append("請輸入"?+?tip?+?"：");
????????System.out.println(help.toString());
????????if?(scanner.hasNext())?{
????????????String?ipt?=?scanner.next();
????????????if?(StringUtils.isNotEmpty(ipt))?{
????????????????return?ipt;
????????????}
????????}
????????throw?new?MybatisPlusException("請輸入正確的"?+?tip?+?"！");
????}
}

4.4 Redis 配置

我們?nèi)绻诖a中使用 RedisTemplate 的話，需要添加相關配置，將其注入到Spring容器中。

@Configuration
public?class?RedisTemplateConfig?{
????@Bean
????public?RedisTemplate?redisTemplate(RedisConnectionFactory?redisConnectionFactory)?{
????????RedisTemplate?redisTemplate?=?new?RedisTemplate<>();
????????redisTemplate.setConnectionFactory(redisConnectionFactory);
????????//?使用Jackson2JsonRedisSerialize?替換默認序列化
????????Jackson2JsonRedisSerializer?jackson2JsonRedisSerializer?=?new?Jackson2JsonRedisSerializer(Object.class);

????????ObjectMapper?objectMapper?=?new?ObjectMapper();
????????objectMapper.setVisibility(PropertyAccessor.ALL,?JsonAutoDetect.Visibility.ANY);
????????objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);

????????SimpleModule?simpleModule?=?new?SimpleModule();
????????simpleModule.addSerializer(DateTime.class,?new?JodaDateTimeJsonSerializer());
????????simpleModule.addDeserializer(DateTime.class,?new?JodaDateTimeJsonDeserializer());
????????objectMapper.registerModule(simpleModule);

????????jackson2JsonRedisSerializer.setObjectMapper(objectMapper);
????????//?設置value的序列化規(guī)則和?key的序列化規(guī)則
????????redisTemplate.setValueSerializer(jackson2JsonRedisSerializer);
????????redisTemplate.setKeySerializer(new?StringRedisSerializer());

????????redisTemplate.setHashKeySerializer(new?StringRedisSerializer());
????????redisTemplate.setHashValueSerializer(jackson2JsonRedisSerializer);

????????redisTemplate.afterPropertiesSet();
????????return?redisTemplate;
????}

}

class?JodaDateTimeJsonSerializer?extends?JsonSerializer?{
????@Override
????public?void?serialize(DateTime?dateTime,?JsonGenerator?jsonGenerator,?SerializerProvider?serializerProvider)?throws?IOException?{
????????jsonGenerator.writeString(dateTime.toString("yyyy-MM-dd?HH:mm:ss"));
????}
}

class?JodaDateTimeJsonDeserializer?extends?JsonDeserializer?{
????@Override
????public?DateTime?deserialize(JsonParser?jsonParser,?DeserializationContext?deserializationContext)?throws?IOException,?JsonProcessingException?{
????????String?dateString?=?jsonParser.readValueAs(String.class);
????????DateTimeFormatter?dateTimeFormatter?=?DateTimeFormat.forPattern("yyyy-MM-dd?HH:mm:ss");
????????return?dateTimeFormatter.parseDateTime(dateString);
????}
}

4.5 常量管理

由于代碼中會用到一些共有的常量，我們應該將其抽離出來。

public?class?LotteryConstants?{

????/**
?????*?表示正在抽獎的用戶標記
?????*/
????public?final?static?String?DRAWING?=?"DRAWING";
????
????/**
?????*?活動標記?LOTTERY:lotteryID
?????*/
????public?final?static?String?LOTTERY?=?"LOTTERY";
????
????/**
?????*?獎品數(shù)據(jù)??LOTTERY_PRIZE:lotteryID:PrizeId
?????*/
????public?final?static?String?LOTTERY_PRIZE?=?"LOTTERY_PRIZE";
????
????/**
?????*?默認獎品數(shù)據(jù)??DEFAULT_LOTTERY_PRIZE:lotteryID
?????*/
????public?final?static?String?DEFAULT_LOTTERY_PRIZE?=?"DEFAULT_LOTTERY_PRIZE";

????public?enum?PrizeTypeEnum?{
????????THANK(-1),?NORMAL(1),?UNIQUE(2);
????????private?int?value;

????????private?PrizeTypeEnum(int?value)?{
????????????this.value?=?value;
????????}

????????public?int?getValue()?{
????????????return?this.value;
????????}
????}

????/**
?????*?獎項緩存：LOTTERY_ITEM:LOTTERY_ID
?????*/
????public?final?static?String?LOTTERY_ITEM?=?"LOTTERY_ITEM";
????
????/**
?????*?默認獎項：DEFAULT_LOTTERY_ITEM:LOTTERY_ID
?????*/
????public?final?static?String?DEFAULT_LOTTERY_ITEM?=?"DEFAULT_LOTTERY_ITEM";

}

public?enum?ReturnCodeEnum?{

????SUCCESS("0000",?"成功"),

????LOTTER_NOT_EXIST("9001",?"指定抽獎活動不存在"),

????LOTTER_FINISH("9002",?"活動已結束"),

????LOTTER_REPO_NOT_ENOUGHT("9003",?"當前獎品庫存不足"),

????LOTTER_ITEM_NOT_INITIAL("9004",?"獎項數(shù)據(jù)未初始化"),

????LOTTER_DRAWING("9005",?"上一次抽獎還未結束"),

????REQUEST_PARAM_NOT_VALID("9998",?"請求參數(shù)不正確"),

????SYSTEM_ERROR("9999",?"系統(tǒng)繁忙,請稍后重試");

????private?String?code;

????private?String?msg;

????private?ReturnCodeEnum(String?code,?String?msg)?{
????????this.code?=?code;
????????this.msg?=?msg;
????}

????public?String?getCode()?{
????????return?code;
????}

????public?String?getMsg()?{
????????return?msg;
????}

????public?String?getCodeString()?{
????????return?getCode()?+?"";
????}
}

對Redis中的key進行統(tǒng)一的管理。

public?class?RedisKeyManager?{

????/**
?????*?正在抽獎的key
?????*
?????*?@param?accountIp
?????*?@return
?????*/
????public?static?String?getDrawingRedisKey(String?accountIp)?{
????????return?new?StringBuilder(LotteryConstants.DRAWING).append(":").append(accountIp).toString();
????}

????/**
?????*?獲取抽獎活動的key
?????*
?????*?@param?id
?????*?@return
?????*/
????public?static?String?getLotteryRedisKey(Integer?id)?{
????????return?new?StringBuilder(LotteryConstants.LOTTERY).append(":").append(id).toString();
????}

????/**
?????*?獲取指定活動下的所有獎品數(shù)據(jù)
?????*
?????*?@param?lotteryId
?????*?@return
?????*/
????public?static?String?getLotteryPrizeRedisKey(Integer?lotteryId)?{
????????return?new?StringBuilder(LotteryConstants.LOTTERY_PRIZE).append(":").append(lotteryId).toString();
????}

????public?static?String?getLotteryPrizeRedisKey(Integer?lotteryId,?Integer?prizeId)?{
????????return?new?StringBuilder(LotteryConstants.LOTTERY_PRIZE).append(":").append(lotteryId).append(":").append(prizeId).toString();
????}

????public?static?String?getDefaultLotteryPrizeRedisKey(Integer?lotteryId)?{
????????return?new?StringBuilder(LotteryConstants.DEFAULT_LOTTERY_PRIZE).append(":").append(lotteryId).toString();
????}

????public?static?String?getLotteryItemRedisKey(Integer?lotteryId)?{
????????return?new?StringBuilder(LotteryConstants.LOTTERY_ITEM).append(":").append(lotteryId).toString();
????}

????public?static?String?getDefaultLotteryItemRedisKey(Integer?lotteryId)?{
????????return?new?StringBuilder(LotteryConstants.DEFAULT_LOTTERY_ITEM).append(":").append(lotteryId).toString();
????}
}

4.6 業(yè)務代碼

4.6.1 抽獎接口

我們首先編寫抽獎接口，根據(jù)前臺傳的參數(shù)查詢到具體的活動，然后進行相應的操作。（當然，前端直接是寫死的/lottery/1）

@GetMapping("/{id}")
public?ResultResp?doDraw(@PathVariable("id")?Integer?id,?HttpServletRequest?request)?{
????String?accountIp?=?CusAccessObjectUtil.getIpAddress(request);
????log.info("begin?LotteryController.doDraw,access?user?{},?lotteryId,{}:",?accountIp,?id);
????ResultResp?resultResp?=?new?ResultResp<>();
????try?{
????????//判斷當前用戶上一次抽獎是否結束
????????checkDrawParams(id,?accountIp);

????????//抽獎
????????DoDrawDto?dto?=?new?DoDrawDto();
????????dto.setAccountIp(accountIp);
????????dto.setLotteryId(id);
????????lotteryService.doDraw(dto);

????????//返回結果設置
????????resultResp.setCode(ReturnCodeEnum.SUCCESS.getCode());
????????resultResp.setMsg(ReturnCodeEnum.SUCCESS.getMsg());
????????//對象轉換
????????resultResp.setResult(lotteryConverter.dto2LotteryItemVo(dto));
????}?catch?(Exception?e)?{
????????return?ExceptionUtil.handlerException4biz(resultResp,?e);
????}?finally?{
????????//清除占位標記
????????redisTemplate.delete(RedisKeyManager.getDrawingRedisKey(accountIp));
????}
????return?resultResp;
}

private?void?checkDrawParams(Integer?id,?String?accountIp)?{
????if?(null?==?id)?{
????????throw?new?RewardException(ReturnCodeEnum.REQUEST_PARAM_NOT_VALID.getCode(),?ReturnCodeEnum.REQUEST_PARAM_NOT_VALID.getMsg());
????}
????//采用setNx命令，判斷當前用戶上一次抽獎是否結束
????Boolean?result?=?redisTemplate.opsForValue().setIfAbsent(RedisKeyManager.getDrawingRedisKey(accountIp),?"1",?60,?TimeUnit.SECONDS);
????//如果為false，說明上一次抽獎還未結束
????if?(!result)?{
????????throw?new?RewardException(ReturnCodeEnum.LOTTER_DRAWING.getCode(),?ReturnCodeEnum.LOTTER_DRAWING.getMsg());
????}
}

為了避免用戶重復點擊抽獎，所以我們通過Redis來避免這種問題，用戶每次抽獎的時候，通過setNx給用戶排隊并設置過期時間；如果用戶點擊多次抽獎，Redis設置值的時候發(fā)現(xiàn)該用戶上次抽獎還未結束則拋出異常。

最后用戶抽獎成功的話，記得清除該標記，從而用戶能夠繼續(xù)抽獎。

4.6.2 初始化數(shù)據(jù)

從抽獎入口進來，校驗成功以后則開始業(yè)務操作。

@Override
public?void?doDraw(DoDrawDto?drawDto)?throws?Exception?{
????RewardContext?context?=?new?RewardContext();
????LotteryItem?lotteryItem?=?null;
????try?{
????????//JUC工具?需要等待線程結束之后才能運行
????????CountDownLatch?countDownLatch?=?new?CountDownLatch(1);
????????//判斷活動有效性
????????Lottery?lottery?=?checkLottery(drawDto);
????????//發(fā)布事件，用來加載指定活動的獎品信息
????????applicationContext.publishEvent(new?InitPrizeToRedisEvent(this,?lottery.getId(),?countDownLatch));
????????//開始抽獎
????????lotteryItem?=?doPlay(lottery);
????????//記錄獎品并扣減庫存
????????countDownLatch.await();?//等待獎品初始化完成
????????String?key?=?RedisKeyManager.getLotteryPrizeRedisKey(lottery.getId(),?lotteryItem.getPrizeId());
????????int?prizeType?=?Integer.parseInt(redisTemplate.opsForHash().get(key,?"prizeType").toString());
????????context.setLottery(lottery);
????????context.setLotteryItem(lotteryItem);
????????context.setAccountIp(drawDto.getAccountIp());
????????context.setKey(key);
????????//調整庫存及記錄中獎信息
????????AbstractRewardProcessor.rewardProcessorMap.get(prizeType).doReward(context);
????}?catch?(UnRewardException?u)?{?//表示因為某些問題未中獎，返回一個默認獎項
????????context.setKey(RedisKeyManager.getDefaultLotteryPrizeRedisKey(lotteryItem.getLotteryId()));
????????lotteryItem?=?(LotteryItem)?redisTemplate.opsForValue().get(RedisKeyManager.getDefaultLotteryItemRedisKey(lotteryItem.getLotteryId()));
????????context.setLotteryItem(lotteryItem);
????????AbstractRewardProcessor.rewardProcessorMap.get(LotteryConstants.PrizeTypeEnum.THANK.getValue()).doReward(context);
????}
????//拼接返回數(shù)據(jù)
????drawDto.setLevel(lotteryItem.getLevel());
????drawDto.setPrizeName(context.getPrizeName());
????drawDto.setPrizeId(context.getPrizeId());
}

首先我們通過CountDownLatch來保證商品初始化的順序，關于CountDownLatch可以查看 JUC工具 該文章。

然后我們需要檢驗一下活動的有效性，確?；顒游唇Y束。

檢驗活動通過后則通過ApplicationEvent 事件實現(xiàn)獎品數(shù)據(jù)的加載，將其存入Redis中?；蛘咄ㄟ^ApplicationRunner在程序啟動時獲取相關數(shù)據(jù)。我們這使用的是事件機制。ApplicationRunner 的相關代碼在下文我也順便貼出。

事件機制

public?class?InitPrizeToRedisEvent?extends?ApplicationEvent?{

????private?Integer?lotteryId;

????private?CountDownLatch?countDownLatch;

????public?InitPrizeToRedisEvent(Object?source,?Integer?lotteryId,?CountDownLatch?countDownLatch)?{
????????super(source);
????????this.lotteryId?=?lotteryId;
????????this.countDownLatch?=?countDownLatch;
????}

????public?Integer?getLotteryId()?{
????????return?lotteryId;
????}

????public?void?setLotteryId(Integer?lotteryId)?{
????????this.lotteryId?=?lotteryId;
????}

????public?CountDownLatch?getCountDownLatch()?{
????????return?countDownLatch;
????}

????public?void?setCountDownLatch(CountDownLatch?countDownLatch)?{
????????this.countDownLatch?=?countDownLatch;
????}

}

有了事件機制，我們還需要一個監(jiān)聽事件，用來初始化相關數(shù)據(jù)信息。具體業(yè)務邏輯大家可以參考下代碼，有相關的注釋信息，主要就是將數(shù)據(jù)庫中的數(shù)據(jù)添加進redis中，需要注意的是，我們?yōu)榱吮ＷC原子性，是通過HASH來存儲數(shù)據(jù)的，這樣之后庫存扣減的時候就可以通過opsForHash來保證其原子性。

當初始化獎品信息之后，則通過countDown()方法表名執(zhí)行完成，業(yè)務代碼中線程阻塞的地方可以繼續(xù)執(zhí)行了。

@Slf4j
@Component
public?class?InitPrizeToRedisListener?implements?ApplicationListener?{

????@Autowired
????RedisTemplate?redisTemplate;

????@Autowired
????LotteryPrizeMapper?lotteryPrizeMapper;

????@Autowired
????LotteryItemMapper?lotteryItemMapper;

????@Override
????public?void?onApplicationEvent(InitPrizeToRedisEvent?initPrizeToRedisEvent)?{
????????log.info("begin?InitPrizeToRedisListener,"?+?initPrizeToRedisEvent);
????????Boolean?result?=?redisTemplate.opsForValue().setIfAbsent(RedisKeyManager.getLotteryPrizeRedisKey(initPrizeToRedisEvent.getLotteryId()),?"1");
????????//已經(jīng)初始化到緩存中了，不需要再次緩存
????????if?(!result)?{
????????????log.info("already?initial");
????????????initPrizeToRedisEvent.getCountDownLatch().countDown();
????????????return;
????????}
????????QueryWrapper?lotteryItemQueryWrapper?=?new?QueryWrapper<>();
????????lotteryItemQueryWrapper.eq("lottery_id",?initPrizeToRedisEvent.getLotteryId());
????????List?lotteryItems?=?lotteryItemMapper.selectList(lotteryItemQueryWrapper);

????????//如果指定的獎品沒有了，會生成一個默認的獎項
????????LotteryItem?defaultLotteryItem?=?lotteryItems.parallelStream().filter(o?->?o.getDefaultItem().intValue()?==?1).findFirst().orElse(null);

????????Map?lotteryItemMap?=?new?HashMap<>(16);
????????lotteryItemMap.put(RedisKeyManager.getLotteryItemRedisKey(initPrizeToRedisEvent.getLotteryId()),?lotteryItems);
????????lotteryItemMap.put(RedisKeyManager.getDefaultLotteryItemRedisKey(initPrizeToRedisEvent.getLotteryId()),?defaultLotteryItem);
????????redisTemplate.opsForValue().multiSet(lotteryItemMap);

????????QueryWrapper?queryWrapper?=?new?QueryWrapper();
????????queryWrapper.eq("lottery_id",?initPrizeToRedisEvent.getLotteryId());
????????List?lotteryPrizes?=?lotteryPrizeMapper.selectList(queryWrapper);

????????//保存一個默認獎項
????????AtomicReference?defaultPrize?=?new?AtomicReference<>();
????????lotteryPrizes.stream().forEach(lotteryPrize?->?{
????????????if?(lotteryPrize.getId().equals(defaultLotteryItem.getPrizeId()))?{
????????????????defaultPrize.set(lotteryPrize);
????????????}
????????????String?key?=?RedisKeyManager.getLotteryPrizeRedisKey(initPrizeToRedisEvent.getLotteryId(),?lotteryPrize.getId());
????????????setLotteryPrizeToRedis(key,?lotteryPrize);
????????});
????????String?key?=?RedisKeyManager.getDefaultLotteryPrizeRedisKey(initPrizeToRedisEvent.getLotteryId());
????????setLotteryPrizeToRedis(key,?defaultPrize.get());
????????initPrizeToRedisEvent.getCountDownLatch().countDown();?//表示初始化完成
????????log.info("finish?InitPrizeToRedisListener,"?+?initPrizeToRedisEvent);
????}

????private?void?setLotteryPrizeToRedis(String?key,?LotteryPrize?lotteryPrize)?{
????????redisTemplate.setHashValueSerializer(new?Jackson2JsonRedisSerializer<>(Object.class));
????????redisTemplate.opsForHash().put(key,?"id",?lotteryPrize.getId());
????????redisTemplate.opsForHash().put(key,?"lotteryId",?lotteryPrize.getLotteryId());
????????redisTemplate.opsForHash().put(key,?"prizeName",?lotteryPrize.getPrizeName());
????????redisTemplate.opsForHash().put(key,?"prizeType",?lotteryPrize.getPrizeType());
????????redisTemplate.opsForHash().put(key,?"totalStock",?lotteryPrize.getTotalStock());
????????redisTemplate.opsForHash().put(key,?"validStock",?lotteryPrize.getValidStock());
????}
}

上面部分是通過事件的方法來初始化數(shù)據(jù)，下面我們說下ApplicationRunner的方式：

這種方式很簡單，在項目啟動的時候將數(shù)據(jù)加載進去即可。

我們只需要實現(xiàn)ApplicationRunner接口即可，然后在run方法中從數(shù)據(jù)庫讀取數(shù)據(jù)加載到Redis中。

@Slf4j
@Component
public?class?LoadDataApplicationRunner?implements?ApplicationRunner?{


????@Autowired
????RedisTemplate?redisTemplate;

????@Autowired
????LotteryMapper?lotteryMapper;

????@Override
????public?void?run(ApplicationArguments?args)?throws?Exception?{
????????log.info("=========begin?load?lottery?data?to?Redis===========");
????????//加載當前抽獎活動信息
????????Lottery?lottery?=?lotteryMapper.selectById(1);

????????log.info("=========finish?load?lottery?data?to?Redis===========");
????}
}

4.6.3 抽獎

我們在使用事件進行數(shù)據(jù)初始化的時候，可以同時進行抽獎操作，但是注意的是這個時候需要使用countDownLatch.await();來阻塞當前線程，等待數(shù)據(jù)初始化完成。

在抽獎的過程中，我們首先嘗試從Redis中獲取相關數(shù)據(jù)，如果Redis中沒有則從數(shù)據(jù)庫中加載數(shù)據(jù)，如果數(shù)據(jù)庫中也沒查詢到相關數(shù)據(jù)，則表明相關的數(shù)據(jù)沒有配置完成。

獲取數(shù)據(jù)之后，我們就該開始抽獎了。抽獎的核心在于隨機性以及概率性，咱們總不能隨便抽抽都能抽到一等獎吧？所以我們需要在表中設置每個獎項的概率性。如下所示：

在我們抽獎的時候需要根據(jù)概率劃分處相關區(qū)間。我們可以通過Debug的方式來查看一下具體怎么劃分的：

獎項的概率越大，區(qū)間越大；大家看到的順序是不同的，由于我們在上面通過Collections.shuffle(lotteryItems);將集合打亂了，所以這里看到的不是順序展示的。

在生成對應區(qū)間后，我們通過生成隨機數(shù)，看隨機數(shù)落在那個區(qū)間中，然后將對應的獎項返回。這就實現(xiàn)了我們的抽獎過程。

private?LotteryItem?doPlay(Lottery?lottery)?{
????LotteryItem?lotteryItem?=?null;
????QueryWrapper?queryWrapper?=?new?QueryWrapper<>();
????queryWrapper.eq("lottery_id",?lottery.getId());
????Object?lotteryItemsObj?=?redisTemplate.opsForValue().get(RedisKeyManager.getLotteryItemRedisKey(lottery.getId()));
????List?lotteryItems;
????//說明還未加載到緩存中，同步從數(shù)據(jù)庫加載，并且異步將數(shù)據(jù)緩存
????if?(lotteryItemsObj?==?null)?{
????????lotteryItems?=?lotteryItemMapper.selectList(queryWrapper);
????}?else?{
????????lotteryItems?=?(List)?lotteryItemsObj;
????}
????//獎項數(shù)據(jù)未配置
????if?(lotteryItems.isEmpty())?{
????????throw?new?BizException(ReturnCodeEnum.LOTTER_ITEM_NOT_INITIAL.getCode(),?ReturnCodeEnum.LOTTER_ITEM_NOT_INITIAL.getMsg());
????}
????int?lastScope?=?0;
????Collections.shuffle(lotteryItems);
????Map?awardItemScope?=?new?HashMap<>();
????//item.getPercent=0.05?=?5%
????for?(LotteryItem?item?:?lotteryItems)?{
????????int?currentScope?=?lastScope?+?new?BigDecimal(item.getPercent().floatValue()).multiply(new?BigDecimal(mulriple)).intValue();
????????awardItemScope.put(item.getId(),?new?int[]{lastScope?+?1,?currentScope});
????????lastScope?=?currentScope;
????}
????int?luckyNumber?=?new?Random().nextInt(mulriple);
????int?luckyPrizeId?=?0;
????if?(!awardItemScope.isEmpty())?{
????????Set>?set?=?awardItemScope.entrySet();
????????for?(Map.Entry?entry?:?set)?{
????????????if?(luckyNumber?>=?entry.getValue()[0]?&&?luckyNumber?<=?entry.getValue()[1])?{
????????????????luckyPrizeId?=?entry.getKey();
????????????????break;
????????????}
????????}
????}
????for?(LotteryItem?item?:?lotteryItems)?{
????????if?(item.getId().intValue()?==?luckyPrizeId)?{
????????????lotteryItem?=?item;
????????????break;
????????}
????}
????return?lotteryItem;
}

4.6.4 調整庫存及記錄

在調整庫存的時候，我們需要考慮到每個獎品類型的不同，根據(jù)不同類型的獎品采取不同的措施。比如如果是一些價值高昂的獎品，我們需要通過分布式鎖來確保安全性；或者比如有些商品我們需要發(fā)送相應的短信；所以我們需要采取一種具有擴展性的實現(xiàn)機制。微信搜索公眾號：Java項目精選，回復：java 領取資料 。

具體的實現(xiàn)機制可以看下方的類圖，我首先定義一個獎品方法的接口（RewardProcessor），然后定義一個抽象類（AbstractRewardProcessor），抽象類中定義了模板方法，然后我們就可以根據(jù)不同的類型創(chuàng)建不同的處理器即可，這大大加強了我們的擴展性。

比如我們這邊就創(chuàng)建了庫存充足處理器及庫存不足處理器。

接口：

public?interface?RewardProcessor?{

????void?doReward(RewardContext?context);

}

抽象類：

@Slf4j
public?abstract?class?AbstractRewardProcessor?implements?RewardProcessor,?ApplicationContextAware?{

????public?static?Map?rewardProcessorMap?=?new?ConcurrentHashMap();

????@Autowired
????protected?RedisTemplate?redisTemplate;

????private?void?beforeProcessor(RewardContext?context)?{
????}

????@Override
????public?void?doReward(RewardContext?context)?{
????????beforeProcessor(context);
????????processor(context);
????????afterProcessor(context);
????}

????protected?abstract?void?afterProcessor(RewardContext?context);


????/**
?????*?發(fā)放對應的獎品
?????*
?????*?@param?context
?????*/
????protected?abstract?void?processor(RewardContext?context);

????/**
?????*?返回當前獎品類型
?????*
?????*?@return
?????*/
????protected?abstract?int?getAwardType();

????@Override
????public?void?setApplicationContext(ApplicationContext?applicationContext)?throws?BeansException?{
????????rewardProcessorMap.put(LotteryConstants.PrizeTypeEnum.THANK.getValue(),?(RewardProcessor)?applicationContext.getBean(NoneStockRewardProcessor.class));
????????rewardProcessorMap.put(LotteryConstants.PrizeTypeEnum.NORMAL.getValue(),?(RewardProcessor)?applicationContext.getBean(HasStockRewardProcessor.class));
????}
}

我們可以從抽象類中的doReward方法處開始查看，比如我們這邊先查看庫存充足處理器中的代碼：

庫存處理器執(zhí)行的時候首相將Redis中對應的獎項庫存減1，這時候是不需要加鎖的，因為這個操作是原子性的。

當扣減后，我們根據(jù)返回的值判斷商品庫存是否充足，這個時候庫存不足則提示未中獎或者返回一個默認商品。

最后我們還需要記得更新下數(shù)據(jù)庫中的相關數(shù)據(jù)。

@Override
protected?void?processor(RewardContext?context)?{
????//扣減庫存（redis的更新）
????Long?result?=?redisTemplate.opsForHash().increment(context.getKey(),?"validStock",?-1);
????//當前獎品庫存不足，提示未中獎，或者返回一個兜底的獎品
????if?(result.intValue()?????????throw?new?UnRewardException(ReturnCodeEnum.LOTTER_REPO_NOT_ENOUGHT.getCode(),?ReturnCodeEnum.LOTTER_REPO_NOT_ENOUGHT.getMsg());
????}
????List