SpringCloud - Feign remote call 2

CSDN Topic Challenge Phase 2
Participation Topic: Study Notes

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This project is based on the dark horse programmer of station B Java "SpringCloud Microservice Technology Stack", SpringCloud+RabbitMQ+Docker+Redis+search+distributed

[SpringCloud+RabbitMQ+Docker+Redis+search+distributed, system detailed springcloud microservice technology stack course|dark horse programmer Java microservice] Click to watch

1. Feign replaces RestTemplate

Click to view

2. Log configuration

1. Log level

NONE: no log
BASIC: request method, URL, response status code and execution time
HEADERS: request method, URL, response status code and execution time and request header and response header
FULL: record header, body and metadata of request and response, almost all information

2. Method 1: Configuration file method

1. Take effect globally

feign:
  client:
    config:
      default:
        logger-level: Full

2. local effect

feign:
  client:
    config:
      userservice: # 服务名名称
        logger-level: Full

3. Method 2: Java code method

1. Create a configuration module config, in which the DefaultFeignConfiguration class is created

package cn.itcast.order.config;

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

public class DefaultFeignConfiguration  {
    
    
    @Bean
    public Logger.Level feignLogLevel(){
    
    
        return Logger.Level.FULL; // 日志级别为
    }
}

2. Global configuration

In the startup class, the heaven is annotated as follows

@EnableFeignClients(defaultConfiguration = DefaultFeignConfiguration.class) //全局生效

3. local configuration

Add the following annotation to the controller class, where value is the service name.

@FeignClient(value = "userservicec" , configuration = DefaultFeignConfiguration.class) // 局部生效

3. Performance optimization

Method : use connection pool (here using Apache HttpClient)

1. import dependencies

<!--HttpClient的依赖-->
<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-httpclient</artifactId>
</dependency>

2. Configure the connection pool (application.yml)

feign:
  httpclient:
    enabled: true
    max-connections: 200
    max-connections-per-route: 50

Recommendation: Use basic or none for log level

4. Best Practices

1. Inheritance

For those with high code coupling, define a unified parent interface and inherit this interface.

2. Extraction

1. Steps

Extract FeignCLient as a separate module

1. Create a new module named feign-api.
2. Introduce feign dependencies

<dependencies>
  <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
  </dependency>
</dependencies>

3. Move the clients, config, pojo modules into the feign-api module.

4. Import feign-api dependency in order-service

 <!--feign-api依赖-->
<dependency>
  <groupId>cn.itcast.demo</groupId>
  <artifactId>feign-api</artifactId>
  <version>1.0</version>
</dependency>

5. Modify the import related to the above three modules in order-service to the package in feign-api
6. restart test

2. Exception

The following exception occurs when restarting:
Field userClient in cn.itcast.order.service.OrderService required a bean of type 'cn.itcast.feign.clients.UserClient' that could not be found.

Reason:
FeignClients is not in the scope of the startup class @SpringBootApplication to scan the package
Solution:
Method 1: Specify the package where FeignClients is located

@EnableFeignClients(defaultConfiguration = DefaultFeignConfiguration.class, basePackages = "cn.itcast.feign.clients") //全局生效

Method 2: Specify FeignClients bytecode

@EnableFeignClients(defaultConfiguration = DefaultFeignConfiguration.class, clients = UserClient.class)