Spring Cloud - 断路器+（普通调用和feign封装调用）

深碍√TFBOYSˉ_ 2022-05-18 05:12 152阅读 0赞

**(三) Spring Cloud - 断路器+（普通调用和feign封装调用）**

1. Ribbon+Hystrix(断路器), **普通调用方式**

**pom.xml加入两个Hystrix依赖maven**

1.  `<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"`
2.  `xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">`
3.  `<modelVersion>4.0.0</modelVersion>`
4.  `<groupId>com.sample</groupId>`
5.  `<artifactId>2017-Netflix_Ribbon</artifactId>`
6.  `<version>1.0.1-SNAPSHOT</version>`
7.  `<packaging>war</packaging>`
8.   
9.  `<build>`
10. `<plugins>`
11. `<plugin>`
12. `<groupId>org.apache.maven.plugins</groupId>`
13. `<artifactId>maven-compiler-plugin</artifactId>`
14. `<version>3.3</version>`
15. `<configuration>`
16. ``
17. `<source>1.8</source>`
18. `<target>1.8</target>`
19. `</configuration>`
20. `</plugin>`
21. `</plugins>`
22. `</build>`
23.  
24. `<parent>`
25. `<groupId>org.springframework.boot</groupId>`
26. `<artifactId>spring-boot-starter-parent</artifactId>`
27. `<version>1.5.2.RELEASE</version>`
28. `</parent>`
29. `<dependencyManagement>`
30. `<dependencies>`
31. `<dependency>`
32. `<groupId>org.springframework.cloud</groupId>`
33. `<artifactId>spring-cloud-dependencies</artifactId>`
34. `<version>Dalston.RELEASE</version>`
35. `<type>pom</type>`
36. `<scope>import</scope>`
37. `</dependency>`
38. `</dependencies>`
39. `</dependencyManagement>`
40. `<dependencies>`
41. `<dependency>`
42. `<groupId>org.springframework.cloud</groupId>`
43. `<artifactId>spring-cloud-starter-config</artifactId>`
44. `</dependency>`
45. `<dependency>`
46. `<groupId>org.springframework.cloud</groupId>`
47. `<artifactId>spring-cloud-starter-eureka</artifactId>`
48. `</dependency>`
49. `<dependency>`
50. `<groupId>org.springframework.cloud</groupId>`
51. `<artifactId>spring-cloud-starter-hystrix</artifactId>`
52. `</dependency>`
53. `<dependency>`
54. `<groupId>com.netflix.hystrix</groupId>`
55. `<artifactId>hystrix-javanica</artifactId>`
56. `</dependency>`
57. `</dependencies>`
58.  
59. `</project>`

Ribbon启动的boot application，修改如下

1.  `package com.jack.ssm;`
2.   
3.  `import org.springframework.boot.SpringApplication;`
4.  `import org.springframework.boot.autoconfigure.SpringBootApplication;`
5.  `import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;`
6.  `import org.springframework.cloud.client.discovery.EnableDiscoveryClient;`
7.  `import org.springframework.cloud.client.loadbalancer.LoadBalanced;`
8.  `import org.springframework.context.annotation.Bean;`
9.  `import org.springframework.web.client.RestTemplate;`
10.  
11. `/**`
12. `* ClassName:RibbonApplication.java`
13. `* Date: 2017年5月13日下午5:06:00`
14. `* @author Jack.Huang`
15. `* @version V1.0`
16. `* @since JDK 1.7.0_60/JDK 1.8.0_45`
17. `*/`
18.  
19. `@SpringBootApplication`
20. `@EnableDiscoveryClient`
21. `@EnableCircuitBreaker // 注解开启断路器功能`
22. `public class RibbonApplication {`
23.  
24. `@Bean`
25. `@LoadBalanced`
26. `RestTemplate restTemplate() {`
27. `return new RestTemplate();`
28. `}`
29. `public static void main(String[] args) {`
30. `SpringApplication.run(RibbonApplication.class, args);`
31. `}`
32. `}`

1.  `package com.jack.ssm.controller;`
2.   
3.  `import org.springframework.beans.factory.annotation.Autowired;`
4.  `import org.springframework.web.bind.annotation.RequestMapping;`
5.  `import org.springframework.web.bind.annotation.RequestMethod;`
6.  `import org.springframework.web.bind.annotation.RestController;`
7.  `import org.springframework.web.client.RestTemplate;`
8.   
9.  `import com.jack.ssm.service.ComputeService;`
10.  
11. `/**`
12. `* ClassName:ConsumerController.java`
13. `* Date: 2017年5月13日下午5:10:00`
14. `* @author Jack.Huang`
15. `* @version V1.0`
16. `* @since JDK 1.7.0_60/JDK 1.8.0_45`
17. `*/`
18.  
19. `@RestController`
20. `public class ConsumerController {`
21.  
22. `/*`
23. `* 没有使用断路器之前的代码`
24. `*`
25. `@Autowired`
26. `RestTemplate restTemplate;`
27.  
28. `@RequestMapping(value = "/ribbonCallAddService", method = RequestMethod.GET)`
29. `public String add() {`
30. `// return restTemplate.getForEntity("http://COMPUTE-SERVICE/add?a=10&b=20", String.class).getBody();`
31. `return restTemplate.getForEntity("http://NETFLIX-SERVICE/add?a=10&b=20", String.class).getBody();`
32. `}`
33. `*/`
34.  
35. `/*`
36. `* 使用断路器之后的代码`
37. `*/`
38. `@Autowired`
39. `private ComputeService computeService;`
40.  
41. `@RequestMapping(value = "/ribbonCallAddService", method = RequestMethod.GET)`
42. `public String add() {`
43. `return computeService.addService();`
44. `}`
45. `}`

1.  `package com.jack.ssm.service;`
2.   
3.  `import org.springframework.beans.factory.annotation.Autowired;`
4.  `import org.springframework.stereotype.Service;`
5.  `import org.springframework.web.client.RestTemplate;`
6.   
7.  `import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;`
8.   
9.  `/**`
10. `* ClassName:ComputeService.java`
11. `* Date: 2017年5月15日下午5:18:45`
12. `* @author Jack.Huang`
13. `* @version V1.0`
14. `* @since JDK 1.7.0_60/JDK 1.8.0_45`
15. `*/`
16.  
17. `@Service`
18. `public class ComputeService {`
19.  
20. `@Autowired`
21. `RestTemplate restTemplate;`
22.  
23. `@HystrixCommand(fallbackMethod = "addServiceFallback")`
24. `public String addService() {`
25. `return restTemplate.getForEntity("http://NETFLIX-SERVICE/add?a=10&b=20", String.class).getBody();`
26. `}`
27.  
28. `public String addServiceFallback() {`
29. `return "Error sevice";`
30. `}`
31.  
32. `}`

调用链接：http://localhost:8000/ribbonCallAddService

**2. Feign+Hystrix(断路器)调用方式**

**pom.xml, feign的依赖已经引入了hystrix，无需再引入也可以实现断路器**

1.  `<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"`
2.  `xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">`
3.  `<modelVersion>4.0.0</modelVersion>`
4.  `<groupId>com.sample</groupId>`
5.  `<artifactId>2017-Netflix_Feign</artifactId>`
6.  `<version>1.0.1-SNAPSHOT</version>`
7.  `<packaging>war</packaging>`
8.   
9.  `<build>`
10. `<plugins>`
11. `<plugin>`
12. `<groupId>org.apache.maven.plugins</groupId>`
13. `<artifactId>maven-compiler-plugin</artifactId>`
14. `<version>3.3</version>`
15. `<configuration>`
16. ``
17. `<source>1.8</source>`
18. `<target>1.8</target>`
19. `</configuration>`
20. `</plugin>`
21. `</plugins>`
22. `</build>`
23.  
24. `<parent>`
25. `<groupId>org.springframework.boot</groupId>`
26. `<artifactId>spring-boot-starter-parent</artifactId>`
27. `<version>1.5.2.RELEASE</version>`
28. `</parent>`
29. `<dependencyManagement>`
30. `<dependencies>`
31. `<dependency>`
32. `<groupId>org.springframework.cloud</groupId>`
33. `<artifactId>spring-cloud-dependencies</artifactId>`
34. ``
35. `<version>Dalston.RELEASE</version>`
36. `<type>pom</type>`
37. `<scope>import</scope>`
38. `</dependency>`
39. `</dependencies>`
40. `</dependencyManagement>`
41. `<dependencies>`
42. `<dependency>`
43. `<groupId>org.springframework.cloud</groupId>`
44. `<artifactId>spring-cloud-starter-config</artifactId>`
45. `</dependency>`
46. `<dependency>`
47. `<groupId>org.springframework.cloud</groupId>`
48. `<artifactId>spring-cloud-starter-eureka</artifactId>`
49. `</dependency>`
50. `<dependency>`
51. `<groupId>org.springframework.cloud</groupId>`
52. `<artifactId>spring-cloud-starter-feign</artifactId>`
53. `</dependency>`
54. ``
58. `</dependencies>`
59.  
60. `</project>`

application.yml, Dalston.RELEASE版本默认关闭hystrix, 其它版本则是默认打开

**[https://github.com/spring-cloud/spring-cloud-netflix/issues/1277][https_github.com_spring-cloud_spring-cloud-netflix_issues_1277]这是spring社区关于为什么默认关闭的解析**

1.  `server:`
2.  `port: 8001`
3.   
4.  `spring:`
5.  `application:`
6.  `name: feign-consumer`
7.   
8.  `eureka:`
9.  `service-url:`
10. `defaultZone: http://localhost:8761/eureka/`
11.  
12. `feign:`
13. `hystrix:`
14. `enabled: true`

1.  `package com.jack.ssm.service;`
2.   
3.  `import org.springframework.cloud.netflix.feign.FeignClient;`
4.  `import org.springframework.web.bind.annotation.RequestMapping;`
5.  `import org.springframework.web.bind.annotation.RequestMethod;`
6.  `import org.springframework.web.bind.annotation.RequestParam;`
7.   
8.  `import com.jack.ssm.service.hystrix.ComputeServiceHystrix;`
9.   
10. `/**`
11. `* ClassName:ComputeService.java`
12. `* Date: 2017年5月13日下午10:06:07`
13. `* @author Jack.Huang`
14. `* @version V1.0`
15. `* @since JDK 1.7.0_60/JDK 1.8.0_45`
16. `*/`
17.  
18. `@FeignClient(name = "NETFLIX-SERVICE", fallback = ComputeServiceHystrix.class)`
19. `public interface ComputeService {`
20.  
21. `@RequestMapping(method = RequestMethod.GET, value = "/add")`
22. `String add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b);`
23.  
24. `}`

1.  `package com.jack.ssm.service.hystrix;`
2.   
3.  `import org.springframework.stereotype.Component;`
4.  `import org.springframework.web.bind.annotation.RequestParam;`
5.   
6.  `import com.jack.ssm.service.ComputeService;`
7.   
8.  `/**`
9.  `* ClassName:ComputeClientHystrix.java`
10. `* Date: 2017年5月15日下午4:14:54`
11. `* @author Jack.Huang`
12. `* @version V1.0`
13. `* @since JDK 1.7.0_60/JDK 1.8.0_45`
14. `*/`
15.  
16. `@Component`
17. `public class ComputeServiceHystrix implements ComputeService {`
18.  
19. `@Override`
20. `public String add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b) {`
21. `return "Error service or service both down!";`
22. `}`
23. `}`

调用链接http://localhost:8001/feignCallAddService

**3.至于feign哪里默认关闭hystrix的源码如下**

**![Center][]**

1.  `/*`
2.  `* Copyright 2013-2016 the original author or authors.`
3.  `*`
4.  `* Licensed under the Apache License, Version 2.0 (the "License");`
5.  `* you may not use this file except in compliance with the License.`
6.  `* You may obtain a copy of the License at`
7.  `*`
8.  `* http://www.apache.org/licenses/LICENSE-2.0`
9.  `*`
10. `* Unless required by applicable law or agreed to in writing, software`
11. `* distributed under the License is distributed on an "AS IS" BASIS,`
12. `* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.`
13. `* See the License for the specific language governing permissions and`
14. `* limitations under the License.`
15. `*/`
16.  
17. `package org.springframework.cloud.netflix.hystrix.security;`
18.  
19. `import javax.annotation.PostConstruct;`
20.  
21. `import org.springframework.beans.factory.annotation.Autowired;`
22. `import org.springframework.boot.autoconfigure.condition.AllNestedConditions;`
23. `import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;`
24. `import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;`
25. `import org.springframework.cloud.netflix.hystrix.security.HystrixSecurityAutoConfiguration.HystrixSecurityCondition;`
26. `import org.springframework.context.annotation.Conditional;`
27. `import org.springframework.context.annotation.Configuration;`
28. `import org.springframework.security.core.context.SecurityContext;`
29.  
30. `import com.netflix.hystrix.Hystrix;`
31. `import com.netflix.hystrix.strategy.HystrixPlugins;`
32. `import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;`
33. `import com.netflix.hystrix.strategy.eventnotifier.HystrixEventNotifier;`
34. `import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;`
35. `import com.netflix.hystrix.strategy.metrics.HystrixMetricsPublisher;`
36. `import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;`
37.  
38. `/**`
39. `* @author Daniel Lavoie`
40. `*/`
41. `@Configuration`
42. `@Conditional(HystrixSecurityCondition.class)`
43. `@ConditionalOnClass({ Hystrix.class, SecurityContext.class })`
44. `public class HystrixSecurityAutoConfiguration {`
45. `@Autowired(required = false)`
46. `private HystrixConcurrencyStrategy existingConcurrencyStrategy;`
47.  
48. `@PostConstruct`
49. `public void init() {`
50. `// Keeps references of existing Hystrix plugins.`
51. `HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance()`
52. `.getEventNotifier();`
53. `HystrixMetricsPublisher metricsPublisher = HystrixPlugins.getInstance()`
54. `.getMetricsPublisher();`
55. `HystrixPropertiesStrategy propertiesStrategy = HystrixPlugins.getInstance()`
56. `.getPropertiesStrategy();`
57. `HystrixCommandExecutionHook commandExecutionHook = HystrixPlugins.getInstance()`
58. `.getCommandExecutionHook();`
59.  
60. `HystrixPlugins.reset();`
61.  
62. `// Registers existing plugins excepts the Concurrent Strategy plugin.`
63. `HystrixPlugins.getInstance().registerConcurrencyStrategy(`
64. `new SecurityContextConcurrencyStrategy(existingConcurrencyStrategy));`
65. `HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);`
66. `HystrixPlugins.getInstance().registerMetricsPublisher(metricsPublisher);`
67. `HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);`
68. `HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);`
69. `}`
70.  
71. `static class HystrixSecurityCondition extends AllNestedConditions {`
72.  
73. `public HystrixSecurityCondition() {`
74. `super(ConfigurationPhase.REGISTER_BEAN);`
75. `}`
76.  
77. `@ConditionalOnProperty(name = "feign.hystrix.enabled", matchIfMissing = false)`
78. `static class HystrixEnabled {`
79.  
80. `}`
81.  
82. `@ConditionalOnProperty(name = "hystrix.shareSecurityContext")`
83. `static class ShareSecurityContext {`
84.  
85. `}`
86. `}`
87. `}`

1.  `/*`
2.  `* Copyright 2013-2016 the original author or authors.`
3.  `*`
4.  `* Licensed under the Apache License, Version 2.0 (the "License");`
5.  `* you may not use this file except in compliance with the License.`
6.  `* You may obtain a copy of the License at`
7.  `*`
8.  `* http://www.apache.org/licenses/LICENSE-2.0`
9.  `*`
10. `* Unless required by applicable law or agreed to in writing, software`
11. `* distributed under the License is distributed on an "AS IS" BASIS,`
12. `* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.`
13. `* See the License for the specific language governing permissions and`
14. `* limitations under the License.`
15. `*/`
16.  
17. `package org.springframework.cloud.netflix.feign;`
18.  
19. `import java.util.ArrayList;`
20. `import java.util.List;`
21.  
22. `import org.springframework.beans.factory.ObjectFactory;`
23. `import org.springframework.beans.factory.annotation.Autowired;`
24. `import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;`
25. `import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;`
26. `import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;`
27. `import org.springframework.boot.autoconfigure.web.HttpMessageConverters;`
28. `import org.springframework.cloud.netflix.feign.support.ResponseEntityDecoder;`
29. `import org.springframework.cloud.netflix.feign.support.SpringDecoder;`
30. `import org.springframework.cloud.netflix.feign.support.SpringEncoder;`
31. `import org.springframework.cloud.netflix.feign.support.SpringMvcContract;`
32. `import org.springframework.context.annotation.Bean;`
33. `import org.springframework.context.annotation.Configuration;`
34. `import org.springframework.context.annotation.Scope;`
35. `import org.springframework.core.convert.ConversionService;`
36. `import org.springframework.format.support.DefaultFormattingConversionService;`
37. `import org.springframework.format.support.FormattingConversionService;`
38.  
39. `import com.netflix.hystrix.HystrixCommand;`
40.  
41. `import feign.Contract;`
42. `import feign.Feign;`
43. `import feign.Logger;`
44. `import feign.Retryer;`
45. `import feign.codec.Decoder;`
46. `import feign.codec.Encoder;`
47. `import feign.hystrix.HystrixFeign;`
48.  
49. `/**`
50. `* @author Dave Syer`
51. `* @author Venil Noronha`
52. `*/`
53. `@Configuration`
54. `public class FeignClientsConfiguration {`
55.  
56. `@Autowired`
57. `private ObjectFactory<HttpMessageConverters> messageConverters;`
58.  
59. `@Autowired(required = false)`
60. `private List<AnnotatedParameterProcessor> parameterProcessors = new ArrayList<>();`
61.  
62. `@Autowired(required = false)`
63. `private List<FeignFormatterRegistrar> feignFormatterRegistrars = new ArrayList<>();`
64.  
65. `@Autowired(required = false)`
66. `private Logger logger;`
67.  
68. `@Bean`
69. `@ConditionalOnMissingBean`
70. `public Decoder feignDecoder() {`
71. `return new ResponseEntityDecoder(new SpringDecoder(this.messageConverters));`
72. `}`
73.  
74. `@Bean`
75. `@ConditionalOnMissingBean`
76. `public Encoder feignEncoder() {`
77. `return new SpringEncoder(this.messageConverters);`
78. `}`
79.  
80. `@Bean`
81. `@ConditionalOnMissingBean`
82. `public Contract feignContract(ConversionService feignConversionService) {`
83. `return new SpringMvcContract(this.parameterProcessors, feignConversionService);`
84. `}`
85.  
86. `@Bean`
87. `public FormattingConversionService feignConversionService() {`
88. `FormattingConversionService conversionService = new DefaultFormattingConversionService();`
89. `for (FeignFormatterRegistrar feignFormatterRegistrar : feignFormatterRegistrars) {`
90. `feignFormatterRegistrar.registerFormatters(conversionService);`
91. `}`
92. `return conversionService;`
93. `}`
94.  
95. `@Configuration`
96. `@ConditionalOnClass({ HystrixCommand.class, HystrixFeign.class })`
97. `protected static class HystrixFeignConfiguration {`
98. `@Bean`
99. `@Scope("prototype")`
100. `@ConditionalOnMissingBean`
101. `@ConditionalOnProperty(name = "feign.hystrix.enabled", matchIfMissing = false)`
102. `public Feign.Builder feignHystrixBuilder() {`
103. `return HystrixFeign.builder();`
104. `}`
105. `}`
106.  
107. `@Bean`
108. `@ConditionalOnMissingBean`
109. `public Retryer feignRetryer() {`
110. `return Retryer.NEVER_RETRY;`
111. `}`
112.  
113. `@Bean`
114. `@Scope("prototype")`
115. `@ConditionalOnMissingBean`
116. `public Feign.Builder feignBuilder(Retryer retryer) {`
117. `return Feign.builder().retryer(retryer);`
118. `}`
119.  
120. `@Bean`
121. `@ConditionalOnMissingBean(FeignLoggerFactory.class)`
122. `public FeignLoggerFactory feignLoggerFactory() {`
123. `return new DefaultFeignLoggerFactory(logger);`
124. `}`
125.  
126. `}`

这两个地方都默认关闭了hystrix，@ConditionalOnProperty(name = "feign.hystrix.enabled", matchIfMissing = false)，实际两个都一起工作，这个有待后续研究![骂人][curse.gif]  
  
本文依然是参考http://blog.didispace.com/springcloud3/，再加上自己翻阅官网源码。

[https_github.com_spring-cloud_spring-cloud-netflix_issues_1277]: https://github.com/spring-cloud/spring-cloud-netflix/issues/1277
[Center]: /images/20220518/d5f3dd06bed04bcca87d03b01c2944e9.png
[curse.gif]: /images/20220518/1f8fef3302b14623be5c7cee23b31599.png