sentinel接入记录

      1.引入pom依赖

     

<!-- SpringCloud ailibaba sentinel-datasource-nacos 持久化需要用到--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-datasource-nacos</artifactId></dependency><!-- SpringCloud ailibaba sentinel--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency>
<dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-transport-simple-http</artifactId></dependency><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-web-servlet</artifactId></dependency><!-- SpringCloud ailibaba sentinel-datasource-nacos 持久化需要用到--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-datasource-nacos</artifactId></dependency><!-- 引入 Sentinel 数据源 --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-sentinel-datasource</artifactId></dependency>
<dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-core</artifactId></dependency><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-annotation-aspectj</artifactId></dependency>

 版本好统一按照

<version>1.8.3</version> 
为例。

2.本机启动
 首先需要再idea的启动脚本添加命令

-Dserver.port=8080 -Dcsp.sentinel.dashboard.server=localhost:8081 -Dproject.name=项目别名

 其中，-Dserver.port是自己的项目名称，-Dcsp.sentinel.dashboard.server  是sentinel开启控制台的端口号，-Dproject是自己的项目名称

3.再项目里面使用sentinel做限流

    sentinel 有两种方式都可以做限流和降级，一种方式是直接再spring bean里面使用fallback以及blockHandler注解，另外一种方式则是和openFeign整合。目前项目里面使用的是第一种方式。

     注意一点，使用sentinel需要相应的bean被spring容器加载进去。

   

@Service
public class QueryRecommentServiceImpl{@SentinelResource(value = "queryRecommend", fallback = "getStaticData",blockHandler = "blockExceptionHandler")public List<String> queryRecommend(HomeRecommendStreamQuery query, HomeRecommendStreamDto streamDto, String sourceApp) {return null;
}public List<String> getStaticData(HomeRecommendStreamQuery query, HomeRecommendStreamDto streamDto, String sourceApp) {logger.info("==========start sentinel 降级策略==========");try {Random random = new Random();int r = random.nextInt(100) + 1;logger.debug("========随机从缓存获取一组帖子id:" + r);Set<String> stringSet = gwmRedisTemplate.opsForValue().get(RedisConstants.THREAD_HOT_SCORE_KEY + r);logger.debug("=========随机从缓存获取帖子result=======" + JSONObject.toJSON(stringSet));if (CollectionUtils.isNotEmpty(stringSet)) {List<String> stringList = new ArrayList<>(stringSet);return stringList;} else {logger.debug("============读取默认配置数据========" + config.getPostIds());return Optional.ofNullable(config.getPostIds()).orElse(Collections.emptyList());}} catch (Exception e) {throw new RuntimeException(e);}}/*** blockHandler需要设置为static** @param ex* @return*/public  List<String> blockExceptionHandler(HomeRecommendStreamQuery query, HomeRecommendStreamDto streamDto, String sourceApp,BlockException ex) {try {Random random = new Random();int r = random.nextInt(100) + 1;logger.debug("========随机从缓存获取一组帖子id:" + r);Set<String> stringSet = gwmRedisTemplate.opsForValue().get(RedisConstants.THREAD_HOT_SCORE_KEY + r);logger.debug("=========随机从缓存获取帖子result=======" + JSONObject.toJSON(stringSet));if (CollectionUtils.isNotEmpty(stringSet)) {List<String> stringList = new ArrayList<>(stringSet);return stringList;} else {logger.debug("============读取默认配置数据========" + config.getPostIds());return Optional.ofNullable(config.getPostIds()).orElse(Collections.emptyList());}} catch (Exception e) {throw new RuntimeException(e);}}}

  

Sentinel 提供了 @SentinelResource 注解用于定义资源，并提供了 AspectJ 的扩展用于自动定义资源、处理 BlockException 等。使用 Sentinel Annotation AspectJ Extension 的时候需要引入以下依赖：

<dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-annotation-aspectj</artifactId><version>x.y.z</version>
</dependency>

 之后再控制台界面就可以进行设置了。

 另外就是如果想要每次启动让sentinel生效，需要再配置一个sentienl的yaml配置，每次项目启动可以自动生效，大概格式如下：

 

[{"resource":"queryRecommend","controlBehavior":0,"count":20,"grade":1,"limitApp":"default","strategy":0}
]