作者:qaz2502919927 | 来源:互联网 | 2023-08-19 15:50
1 引言
Feign可以帮助我们面向接口编程,就直接调用其他服务,简化开发
2 快速入门
1、导入依赖
<dependency><groupId>org.springframework.cloudgroupId><artifactId>spring-cloud-starter-openfeignartifactId>
dependency>
2、添加一个注解
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class ClientApplication {public static void main(String[] args) {SpringApplication.run(ClientApplication.class,args);}@Bean@LoadBalancedpublic RestTemplate getRestTemplate() {return new RestTemplate();}
}
3、创建一个接口,并且和search模块做映射
@FeignClient("SEARCH")
public interface SearchClient {@RequestMapping(value = "/search",method = RequestMethod.GET)String search();
}
4、测试使用
@RestController
public class CustomController {@Autowiredprivate SearchClient searchClient; @GetMapping("/customer")public String customer() {String search = searchClient.search();return search;}
}
3 Feign的传递参数方式
1、注意事项
- 如果传递的参数比较复杂,默认会采用POST的请求方式
- 如果传递单个参数,推荐使用@PathVariable。如果传递的单个参数比较多,也可以采用@RequestParma,不要省略value属性。
- 传递对象信息时,统一采用json的方式,添加@RequestBody
- Client接口必须采用@RequestMapping
2、在search模块下准备三个接口
@FeignClient("SEARCH")
public interface SearchClient {@RequestMapping(value = "/search/{id}",method = RequestMethod.GET)Customer findById(@PathVariable(value = "id") Integer id);@RequestMapping(value = "/getCustomer",method = RequestMethod.GET)Customer getCustomer(@RequestParam(value = "id") Integer id, @RequestParam(value = "name") String name);}
3、封装customer模块下的controller
@RestController
public class CustomController {@Autowiredprivate SearchClient searchClient;@GetMapping("/customer/{id}")public Customer findById(@PathVariable(value = "id") Integer id) {return searchClient.findById(id);}@GetMapping("/getCustomer")public Customer getCustomer(@RequestParam Integer id,@RequestParam String name) {return searchClient.getCustomer(id,name);}
}
4 Feign的Fallback
fallback可以帮助feign去调用另外一个服务时,如果出现了问题,走服务降级,返回一个错误数据,避免因为一个服务出现问题,导致全部服务失效。
1、创建一个POJO类,实现Client接口
@Component
public class SearchClientFallBack implements SearchClient {@Overridepublic String search() {return "出现问题!!!";}@Overridepublic Customer findById(Integer id) {return null;}@Overridepublic Customer getCustomer(Integer id, String name) {return null;}@Overridepublic Customer save(Customer customer) {return null;}
}
2、修改Client接口中的注解,天界一个Fallback属性
@FeignClient(value = "SEARCH",fallback = SearchClientFallBack.class)
3、添加一个配置文件。
feign:hystrix:enabled: true
调用方无法知道错误信息是什么,可以通过FallbackFactory的方式取实现这个功能
FallbackFactory基于Fallback
创建一个POJO类,实现FallbackFactory
@Component
public class SearchClientFallBackFactory implements FallbackFactory<SearchClient> {@Autowiredprivate SearchClientFallBack searchClientFallBack;@Overridepublic SearchClient create(Throwable throwable) {throwable.printStackTrace();return searchClientFallBack;}
}
修改Client接口中的属性.
@FeignClient(value = "SEARCH",fallbackFactory = SearchClientFallBackFactory.class)