http客户端Feign

引入依赖

---

		<dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-openfeignartifactId>
        dependency>
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启动类添加注解

---

@EnableFeignClients
@MapperScan("cn.zyw.order.mapper")
@SpringBootApplication
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

}
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编写FeignClient接口

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import cn.zyw.order.pojo.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient("userservice")
public interface UserClient {

    @GetMapping("/user/{id}")
    User findById(@PathVariable("id") Long id);

}
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使用FeignClient接口

---

@Service
public class OrderService {

    @Autowired
    private OrderMapper orderMapper;
    
    @Autowired
    private UserClient userClient;


    public Order queryOrderById(Long orderId) {
        // 1.查询订单
        Order order = orderMapper.findById(orderId);
        // 2.用Feign远程调用
        User user = userClient.findById(order.getUserId());
        // 3. 封装user到Order
        order.setUser(user);
        // 4.返回
        return order;
    }
}
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自定义配置

---

配置Feign日志

配置文件方式

• 全局生效

feign:
  client:
    config:
      default:     # 这里用default就是全局配置,
        logger-level: : basic
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• 局部生效

feign:
  client:
    config:
      userservice:     # userservice为服务名
        logger-level: : basic
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代码方式

声明一个Bean

import feign.Logger;
import org.springframework.context.annotation.Bean;

public class FeignClientConfiguration {
    @Bean
    public Logger.Level feignLogLevel(){
        return Logger.Level.BASIC;
    }
}
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• 全局生效

@EnableFeignClients(defaultConfiguration = FeignClientConfiguration.class)
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• 局部生效

@FeignClient(value = "userservice", configuration = FeignClientConfiguration.class)
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性能优化

---

引入依赖

		<dependency>
            <groupId>io.github.openfeigngroupId>
            <artifactId>feign-httpclientartifactId>
        dependency>
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修改配置

feign:
  httpclient:
    enabled: true   # 开启feign对httpclient的支持
    max-connections: 200    # 最大连接数
    max-connections-per-route: 50   # 每个路径的最大连接数
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最佳实践

---

• 创建feign-api子模块
• 引入openfeign依赖
• 将UserClient和pojo等移到该模块下

其他模块引入feign-api依赖,@EnableFeignClients属性中增加basePackages或clients属性

 
        <dependency>
            <groupId>cn.zyw.demogroupId>
            <artifactId>feign-apiartifactId>
            <version>1.0version>
        dependency>
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@EnableFeignClients(basePackages = "cn.zyw.feign.clients", defaultConfiguration = FeignClientConfiguration.class)
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@EnableFeignClients(clients = {UserClient.class}, defaultConfiguration = FeignClientConfiguration.class)
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