[](()在启动类上添加@EnableFeignClients注解来启用Feign的客户端功能
@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class FeignServiceApplication {
public static void main(String[] args) {
SpringApplication.run(FeignServiceApplication.class, args);
}
}
[](()添加UserService接口完成对user-service服务的接口绑定
@FeignClient(value = “user-service”, fallback = UserFallbackService.class)
public interface UserService {
@PostMapping(“/user/insert”)
Result insert(@RequestBody User user);
@GetMapping(“/user/{id}”)
Result getUser(@PathVariable Long id);
@GetMapping(“/user/listUsersByIds”)
Result<List> listUsersByIds(@RequestParam List ids);
@GetMapping(“/user/getByUsername”)
Result getByUsername(@RequestParam String username);
@PostMapping(“/user/update”)
Result update(@RequestBody User user);
@PostMapping(“/user/delete/{id}”)
Result delete(@PathVariable Long id);
}
[](()添加UserFeignController调用UserService实现服务调用
@RestController
@RequestMapping(“/user”)
public class UserFeignController {
@Autowired
private UserService userService;
@PostMapping(“/insert”)
public Result insert(@RequestBody User user) {
return userService.insert(user);
}
@GetMapping(“/{id}”)
public Result getUser(@PathVariable Long id) {
return userService.getUser(id);
}
@GetMapping(“/listUsersByIds”)
public Result<List> listUsersByIds(@RequestParam List ids) {
return userService.listUsersByIds(ids);
}
@GetMapping(“/getByUsername”)
public Result getByUsername(@RequestParam String username) {
return userService.getByUsername(username);
}
@PostMapping(“/update”)
public Result update(@RequestBody User user) {
return userService.update(user);
}
@PostMapping(“/delete/{id}”)
public Result delete(@PathVariable Long id) {
return userService.delete(id);
}
}
[](()负载均衡功能演示
启动eureka-service，两个user-service，feign-service服务，启动后注册中心显示如下：
多次调用[http://localhost:8701/user/1](()进行测试，可以发现运行在8201和8202的user-service服务交替打印如下信息：
2019-12-27 17:11:57.416 INFO 18096 — [nio-8202-exec-1] c.j.s.controller.UserController : 根据id获取用户信息，用户名称为：jourwon
2019-12-27 17:12:04.897 INFO 18096 — [nio-8202-exec-2] c.j.s.controller.UserController : 根据id获取用户信息，用户名称为：jourwon
2019-12-27 17:12:05.262 INFO 18096 — [nio-8202-exec-3] c.j.s.controller.UserController : 根据id获取用户信息，用户名称为：jourwon
[](()Feign中的服务降级
[](()添加服务降级实现类UserFallbackService
@Component
public class UserFallbackService implements UserService {
@Override
public Result insert(User user) {
return new Result(“调用失败，服务被降级”,500);
}
@Override
public Result getUser(Long id) {
return new Result(“调用失败，服务被降级”,500);
}
@Override
public Result<List> listUsersByIds(List ids) {
return new Result(“调用失败，服务被降级”,500);
}
@Override
public Result getByUsername(String username) {
return new Result(“调用失败，服务被降级”,500);
}
@Override
public Result update(User user) {
return new Result(“调用失败，服务被降级”,500);
}
@Override
public Result delete(Long id) {
return new Result(“调用失败，服务被降级”,500);
}
}
[](()修改UserService接口，设置服务降级处理类为UserFallbackService
@FeignClient(value = “user-service”,fallback = UserFallbackService.class)
public interface UserService {
}
[](()修改application.yml，开启Hystrix功能
#在Feign中开启Hystrix
feign:
hystrix:
enabled: true
[](()服务降级功能演示
关闭两个user-service服务，重新启动feign-service;
调用[http://localhost:8701/user/1](()进行测试，可以发现返回了服务降级信息。
[](()日志打印功能
[](()日志级别
-
NONE：默认的，不显示任何日志；
-
BASIC：仅记录请求方法、URL、响应状态码及执行时间；
-
HEADERS：除了BASIC中定义的信息之外，还有请求和响应的头信息；
-
FULL：除了HEADERS中定义的信息之外，还有请求和响应的正文及元数据。
[](()通过配置开启更为详细的日志
@Configuration
public class FeignConfig {
@Bean
Logger.Level level() {
return Logger.Level.FULL;
}
}
[](()在application.yml中配置需要开启日志的F 《一线大厂Java面试题解析+后端开发学习笔记+最新架构讲解视频+实战项目源码讲义》无偿开源 威信搜索公众号【编程进阶路】 eign客户端
logging:
level:
com.jourwon.springcloud.service: debug
[](()查看日志
2019-12-27 17:16:32.188 DEBUG 18424 — [-user-service-9] c.j.springcloud.service.UserService : [UserService#getUser] —> GET http://user-service/user/1 HTTP/1.1
2019-12-27 17:16:32.188 DEBUG 18424 — [-user-service-9] c.j.springcloud.service.UserService : [UserService#getUser] —> END HTTP (0-byte body)
2019-12-27 17:16:32.192 DEBUG 18424 — [-user-service-9] c.j.springcloud.service.UserService : [UserService#getUser] <— HTTP/1.1 200 (3ms)
2019-12-27 17:16:32.192 DEBUG 18424 — [-user-service-9] c.j.springcloud.service.UserService : [UserService#getUser] connection: keep-alive
2019-12-27 17:16:32.192 DEBUG 18424 — [-user-service-9] c.j.springcloud.service.UserService : [UserService#getUser] content-type: application/json
2019-12-27 17:16:32.192 DEBUG 18424 — [-user-service-9] c.j.springcloud.service.UserService : [UserService#getUser] date: Fri, 27 Dec 2019 09:16:32 GMT
