前言:
如果不知道如何配置sentinel或者不知道如何打开文章中的一些网页,可以参考我前面的文章:
SpringCloud Alibaba学习(五):Sentinel的介绍与搭建
有关流控规则的讲解与实战:SpringCloud Alibaba学习(六):Sentinel的流控规则
有关降级规则的讲解与实战:SpringCloud Alibaba学习(七):Sentinel的降级规则
有关热点规则的讲解与实战:SpringCloud Alibaba学习(八):Sentinel的热点规则
一、准备工作
1、启动Nacos和Sentinel
2、准备两个服务提供者
准备服务提供者 cloudalibaba-provider-payment9003 和 cloudalibaba-provider-payment9004,用ribbon实现两者的负载均衡。
9003和9004的结构完全相同。
(1)新建模块
新建普通maven模块cloudalibaba-provider-payment9003
(2)修改pom文件
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <parent> <artifactId>cloud</artifactId> <groupId>com.shang.cloud</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>cloudalibaba-provider-payment9003</artifactId> <dependencies> <!--SpringCloud ailibaba nacos --> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId> </dependency> <dependency><!-- 引入自己定义的api通用包,可以使用Payment支付Entity --> <groupId>com.shang.cloud</groupId> <artifactId>cloud-api-commons</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <!-- SpringBoot整合Web组件 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <!--日常通用jar包配置--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <properties> <maven.compiler.source>8</maven.compiler.source> <maven.compiler.target>8</maven.compiler.target> </properties> </project>
(3)修改yml文件
server: port: 9003 spring: application: name: nacos-payment-provider cloud: nacos: discovery: server-addr: localhost:8848 #配置Nacos地址 management: endpoints: web: exposure: include: '*'
这里要注意9003和9004的端口号是不一样的
(4)编写主启动类
@SpringBootApplication @EnableDiscoveryClient public class PaymentMain9003{ public static void main(String[] args) { SpringApplication.run(PaymentMain9003.class, args); } }
(5)编写业务代码
controller包下:
@RestController public class PaymentController{ @Value("${server.port}") private String serverPort; //模拟数据库中的数据 public static HashMap<Long, Payment> hashMap = new HashMap<>(); static{ hashMap.put(1L,new Payment(1L,"28a8c1e3bc2742d8848569891fb42181")); hashMap.put(2L,new Payment(2L,"bba8c1e3bc2742d8848569891ac32182")); hashMap.put(3L,new Payment(3L,"6ua8c1e3bc2742d8848569891xt92183")); } @GetMapping(value = "/paymentSQL/{id}") public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id){ Payment payment = hashMap.get(id); CommonResult<Payment> result = new CommonResult(200,"from mysql,serverPort: "+serverPort,payment); return result; } }
6)运行测试
浏览器访问
http://localhost:9003/paymentSQL/1
http://localhost:9004/paymentSQL/1
看看是不是能正常访问。能正常访问就说明搭建过程没问题。
3、准备一个消费者
(1)新建模块
新建普通maven工程新建cloudalibaba-consumer-nacos-order84
(2)修改pom文件
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <parent> <artifactId>cloud</artifactId> <groupId>com.shang.cloud</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>cloudalibaba-consumer-nacos-order84</artifactId> <dependencies> <!--SpringCloud ailibaba nacos --> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId> </dependency> <!--SpringCloud ailibaba sentinel --> <dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId> </dependency> <!-- 引入自己定义的api通用包,可以使用Payment支付Entity --> <dependency> <groupId>com.shang.cloud</groupId> <artifactId>cloud-api-commons</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <!-- SpringBoot整合Web组件 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <!--日常通用jar包配置--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <properties> <maven.compiler.source>8</maven.compiler.source> <maven.compiler.target>8</maven.compiler.target> </properties> </project>
3)编写yml文件
server: port: 84 spring: application: name: nacos-order-consumer cloud: nacos: discovery: server-addr: localhost:8848 sentinel: transport: #配置Sentinel dashboard地址 dashboard: localhost:8080 #默认8719端口,假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口 port: 8719 #消费者将要去访问的微服务名称(注册成功进nacos的微服务提供者) service-url: nacos-user-service: http://nacos-payment-provider
(4)编写主启动类
@EnableDiscoveryClient @SpringBootApplication public class OrderNacosMain84{ public static void main(String[] args) { SpringApplication.run(OrderNacosMain84.class, args); } }
(5)编写业务代码
config包下,实现负载均衡:
@Configuration public class ApplicationContextConfig { @Bean @LoadBalanced public RestTemplate getRestTemplate() { return new RestTemplate(); } }
controller包下,处理服务熔断:
@RestController @Slf4j public class CircleBreakerController { public static final String SERVICE_URL = "http://nacos-payment-provider"; @Resource private RestTemplate restTemplate; @RequestMapping("/consumer/fallback/{id}") @SentinelResource(value = "fallback") public CommonResult<Payment> fallback(@PathVariable Long id) { CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id); //如果传入的id为4,就模拟Java的运行异常 if (id == 4) { throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常...."); }else if (result.getData() == null) { //如果传入的id是其他(非1、2、3、4,就模拟传入非法参数的异常) throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常"); } return result; } }
我们的逻辑是:假如传入的id为1、2或3,能够正常访问;传入4,将会报非法参数异常(模拟Java的运行异常);传入5,将会报空指针异常。
那么我们在此时访问 http://localhost:84/consumer/fallback/1
能够正常访问。
访问 http://localhost:84/consumer/fallback/4
访问 http://localhost:84/consumer/fallback/5
可以看到,直接显示了报错页面,用户体验非常不友好。
那么下面我们就来配置处理服务熔断的兜底方法。
二、Sentinel+Ribbon实现服务熔断
1、无任何配置
如上面所见,无论是传参异常还是空指针异常,都直接显示error页面,非常不友好。
2、只配置fallback
(1)代码
@RequestMapping("/consumer/fallback/{id}") // @SentinelResource(value = "fallback") //没有配置 @SentinelResource(value = "fallback", fallback = "handlerFallback") //fallback只负责处理业务异常 public CommonResult<Payment> fallback(@PathVariable Long id) { CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id, CommonResult.class,id); //如果传入的id为4,就模拟Java的运行异常 if (id == 4) { throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常...."); }else if (result.getData() == null) { //如果传入的id是其他(非1、2、3、4,就模拟传入非法参数的异常) throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常"); } return result; }
注意SentinelResource的配置,除了value之外,只写了fallback
(2)图解
(3)测试
可以看到,传入4和5时都显示了我们指定的熔断规则。
3、只配置blockHandler
(1)代码
@RequestMapping("/consumer/fallback/{id}") // @SentinelResource(value = "fallback") //没有配置 // @SentinelResource(value = "fallback", fallback = "handlerFallback") //fallback只负责处理业务异常 @SentinelResource(value = "fallback", blockHandler = "handlerFallback") //blockHandler只负责sentinel控制台配置违规 public CommonResult<Payment> fallback(@PathVariable Long id) { CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id, CommonResult.class,id); //如果传入的id为4,就模拟Java的运行异常 if (id == 4) { throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常...."); }else if (result.getData() == null) { //如果传入的id是其他(非1、2、3、4,就模拟传入非法参数的异常) throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常"); } return result; } public CommonResult blockHandler(@PathVariable Long id, BlockException blockException) { Payment payment = new Payment(id,"null"); return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment); }
(2)图解
(3)sentinel配置
其实降级规则里设置哪一个都行,这次我就选用异常数吧。
(4)测试
传入4,直接报错……
传入5,直接报错……
为什么? 原因还是我们一直强调的:blockHandler只负责sentinel的配置错误,不负责Java的运行错误 。
而如果快速刷新页面多次(异常数大于2),就会触发降级,此时才是blockHandler的管辖范围。
4、fallback和blockHandler都配置
(1)代码
@RequestMapping("/consumer/fallback/{id}") // @SentinelResource(value = "fallback") //没有配置 // @SentinelResource(value = "fallback", fallback = "handlerFallback") //fallback只负责处理业务异常 // @SentinelResource(value = "fallback", blockHandler = "handlerFallback") //blockHandler只负责sentinel控制台配置违规 @SentinelResource(value = "fallback", fallback = "handlerFallback", blockHandler = "blockHandler") public CommonResult<Payment> fallback(@PathVariable Long id) { CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id, CommonResult.class,id); //如果传入的id为4,就模拟Java的运行异常 if (id == 4) { throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常...."); }else if (result.getData() == null) { //如果传入的id是其他(非1、2、3、4,就模拟传入非法参数的异常) throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常"); } return result; } public CommonResult handlerFallback(@PathVariable Long id, Throwable e){ Payment payment = new Payment(id, "null"); return new CommonResult<>(444, "兜底异常handlerFallback.exception内容 "+e.getMessage(),payment); } public CommonResult blockHandler(@PathVariable Long id, BlockException blockException) { Payment payment = new Payment(id,"null"); return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment); }
(2)图解
(3)sentinel配置
(4) 测试
因为配置了fallback,所以传入4和5后肯定是会出现兜底的熔断方法的。
那么这里就有一个问题了:
我们在传入4或5时,会触发java运行异常;而快速点击时,会触发sentinel配置的错误。而在这时我快速点击,究竟是fallback中的方法来处理,还是blockHandler中的方法来处理呢?
先上结果:
这说明:若 blockHandler 和 fallback 都进行了配置,则被限流降级而抛出 BlockException 时只会进入 blockHandler 处理逻辑。
为什么?
我们可以这么理解,当我们快速点击时发生降级,此时连服务的大门都没进去就被阻拦了,如何能够报java运行异常呢?所以是blockHandler来处理。
5、还可以配置忽略属性exceptionsToIgnore
(1)代码
@SentinelResource(value = "fallback", fallback = "handlerFallback", blockHandler = "blockHandler", exceptionsToIgnore = {IllegalArgumentException.class})
指定了哪个异常后就可以忽略,不进行限流
(2)图解
(3)测试
三 、Sentinel+OpenFeign实现服务熔断
1、修改84模块
(1)修改pom文件
加上对OpenFeign的支持
<!--SpringCloud openfeign --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency>
(2)修改yml文件
激活Sentinel对Feign的支持
# 激活Sentinel对Feign的支持 feign: sentinel: enabled: true
(3)修改主启动类
主启动类上增加@EnableFeignClients,增加对Feign的支持
(4)编写业务代码
1.带@FeignClient注解的业务接口
@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)//调用中关闭9003服务提供者 public interface PaymentService { @GetMapping(value = "/paymentSQL/{id}") public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id); }
2.兜底的方法
@Component public class PaymentFallbackService implements PaymentService { @Override public CommonResult<Payment> paymentSQL(Long id) { return new CommonResult<>(444,"服务降级返回,没有该流水信息",new Payment(id, "errorSerial......")); } }
3.修改controller类
@RestController @Slf4j public class CircleBreakerController { public static final String SERVICE_URL = "http://nacos-payment-provider"; @Resource private RestTemplate restTemplate; @RequestMapping("/consumer/fallback/{id}") //@SentinelResource(value = "fallback") //没有配置 //@SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback只负责业务异常 //@SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler只负责sentinel控制台配置违规 @SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler", exceptionsToIgnore = {IllegalArgumentException.class}) public CommonResult<Payment> fallback(@PathVariable Long id) { CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id); if (id == 4) { throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常...."); }else if (result.getData() == null) { throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常"); } return result; } //本例是fallback public CommonResult handlerFallback(@PathVariable Long id,Throwable e) { Payment payment = new Payment(id,"null"); return new CommonResult<>(444,"兜底异常handlerFallback,exception内容 "+e.getMessage(),payment); } //本例是blockHandler public CommonResult blockHandler(@PathVariable Long id,BlockException blockException) { Payment payment = new Payment(id,"null"); return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment); } //==================OpenFeign @Resource private PaymentService paymentService; @GetMapping(value = "/consumer/openfeign/{id}") public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id) { if(id == 4) { throw new RuntimeException("没有该id"); } return paymentService.paymentSQL(id); }
2、测试
启动Nacos、sentinel、84、9003,访问
http://localhost:84/consumer/paymentSQL/1
能够正常访问。
现在我们关掉9003,再次访问:
84消费侧主动降级,并不会直接显示错误页面。
四、熔断框架比较