Openfeign service interface call

One 、 summary

1.1 Feign Introduce

Feign yes Netflix Developed declarative , templated HTTP client , It's inspired by Retrofit,JAXRS-2.0 as well as WebSocket.

• Feign Can help us more convenient , Elegant call HTTP API.
• stay SpringCloud in , Use Feign It's simple —— Create an interface , And add some comments to the interface , The code is done .
• Feign Support multiple annotations , for example Feign Own notes or JAX-RS Annotations etc. .
• SpringCloud Yes Feign Enhanced , send Feign Support SpringMVC annotation , And integrated Ribbon and Eureka, So that Feign It is more convenient to use .

Official website ：https://cloud.spring.io/spring-cloud-static/Hoxton.SR1/reference/htmlsingle/#spring-cloud-openfeign

GitHub：https://github.com/spring-cloud/spring-cloud-openfeign

1.2 Feign The role of

Feign Designed to make writing Java Http The client becomes easier .
In front of the use of Ribbon + RestTemplate when , utilize RestTemplate Yes Http Encapsulation processing of requests , It forms a set of template calling methods . But in actual development , Because there may be more than one call to the service , Often an interface is called in multiple places , So we usually encapsulate some client classes for each microservice to package the calls of these dependent services . therefore ,Feign On this basis, we make further encapsulation , It's up to him to help us define and implement the definition of the dependent service interface . stay Feign Under the realization of , We just need to create an interface and use annotations to configure it （ It used to be DAO Mark... On the interface @Mapper annotation , Now it's a microservice interface with a Feign Annotations can be ）, You can complete the interface binding to the service provider , Simplified use SpringCloud Ribbon when , Development volume of auto encapsulation service calling client .

Feign Integrated Ribbon, utilize Ribbon Maintain the service list information of the service provider , And through polling to achieve the client load balancing . And with the Ribbon The difference is , adopt Feign Just define the service binding interface and use declarative methods , Elegant and simple implementation of service invocation .

1.3 Feign and OpenFeign The difference between

Feign	OpenFeign
Feign yes SpringCloud One of the lightweight components RESTful Of HTTP Service client .Feign Built in Ribbon, It is used for client load balancing , To call the service in the service registry .Feign Is used in the following way ： Use Feign The annotation defines the interface , Call this interface , You can call the service in the service registry .	OpenFeign yes SpringCloud stay Feign Based on the support of SpringMVC Annotations @RequestMapping wait .OpenFeign Of @FeignClient Can be parsed SpringMVC Of @RequestMapping Interface under annotation , And through the way of dynamic proxy to produce the implementation class , Load balancing in the implementation class and calling other services .
<dependency>      <groupId>org.springframework.cloud</groupId>      <artifactId>spring-cloud-starter- feign</artifactId> </dependency>	<dependency>      <groupId>org.springframework.cloud</ groupId>      <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency>

Two 、 be based on OpenFeign Service call for

2.1 Introduce dependencies

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud2020</artifactId>
        <groupId>com.atguigu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumer-feign-order80</artifactId>


    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
    </dependencies>

</project>

2.2 To configure application.yml

server:
  port: 80

eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/

2.3 Start the main class configuration , And add Feign Support for

@SpringBootApplication
@EnableFeignClients
public class OrderFeignMain80 {
    
    public static void main(String[] args) {
    
        SpringApplication.run(OrderFeignMain80.class, args);
    }
}

adopt @EnableFeignClients Annotations to open SpringCloud Feign Support functions of .

2.4 Start class activation FeignClient

Create a Feign Interface , This interface is in Feign The core interface for invoking microservices in .
In serving consumers cloud-consumer-feign-order80 Create a PaymentFeignService Interface and add comments @FeignClient

@Service
@FeignClient(name = "CLOUD-PAYMENT-SERVICE")
public interface PaymentFeignService {
    

    @GetMapping(value = "/payment/get/{id}")
    CommonResult<Payment> getPaymentById(@PathVariable("id") Long id);
}

• When defining the binding of each parameter ,@PathVariable、@RequestParam、@RequestHeader Parameter properties can be specified , stay Feign The binding parameter in must pass value Property to specify the specific parameter name , Otherwise, an exception will be thrown .
• @FeignClient Comments by name Specify the name of the micro service to be called , Used to create Ribbon Load balancer for . therefore Ribbon Will be able to CLOUD-PAYMENT-SERVICE Service resolved to registry .

2.5 Configure the calling interface of the request provider

@RestController
@Slf4j
public class OrderFeignController {
    
    @Resource
    private PaymentFeignService paymentFeignService;

    @GetMapping("/consumer/payment/get/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id){
    
        return paymentFeignService.getPaymentById(id);
    }
}

2.6 test

Start... First 2 individual eureka colony 7001/7002, Restart 2 Micro services 8001/8002, Finally start OpenFeign
visit http://localhost/consumer/payment/get/31


It can be seen that Feign Load balancing item with its own configuration .Feign Has been integrated in Ribbon Dependency and auto configuration , So we don't need to introduce additional dependencies , No need to register again RestTemplate object . in addition , If you want to modify Ribbon Configuration of , Can still pass ribbon.xx For global configuration . It can also be done through service name .ribbon.xxx To configure the specified service .

2.7 summary

3、 ... and 、Feign and Ribbon The connection of

Ribbon It's based on HTTP and TCP Load balancing tools for clients , It can be configured on the client side RibbonServerList（ Server list ）, Use HttpClient or RestTemplate simulation http request , The steps are rather tedious .

Feign Is in Ribbon Based on this, an improvement is made , It is more convenient to use HTTP client . Interface mode , Just create an interface , Then add comments on it , Define the methods of other services that need to be called as abstract methods , You don't need to build it yourself http request . When called, it is like calling the method of its own project , It doesn't feel like a remote method call , It makes it very easy to write the client .

Four 、 Timeout control

Feign When the client calls the server , The default waiting time for program execution is 1 Second , If timeout occurs, an error will be reported . But generally, the server processing may exceed 1 Second , To avoid that , We need to set Feign Timeout control of client .

4.1 When the demo is over

4.1.1 service provider 8001 and 8002 Add a pause program

Add the following code to 8001 and 8002 Of PaymentController Class ：

@GetMapping("/payment/feign/timeout")
public String paymentFeignTimeOut(){
    
    System.out.println("*****************paymentFeignTimeOut from serverPort:" + serverPort);
    try {
    
        TimeUnit.SECONDS.sleep(3);
    } catch (InterruptedException e){
    
        e.printStackTrace();
    }
    return serverPort;
}

4.1.2 Service consumer 80 Add timeout method

stay PaymentFeignService Add the following code to ：

@Service
@FeignClient(value = "CLOUD-PAYMENT-SERVICE")
public interface PaymentFeignService {
    
    @GetMapping(value = "/payment/feign/timeout")
    String paymentFeignTimeOut();
}

stay OrderFeignController Add the following code to ：

@RestController
@Slf4j
public class OrderFeignController {
    
    @Resource
    private PaymentFeignService paymentFeignService;

   @GetMapping("/consumer/payment/feign/timeout")
   public String paymentFeignTimeOut(){
    
        return paymentFeignService.paymentFeignTimeOut();
   }
}

4.1.3 test

visit http://localhost/consumer/payment/feign/timeout

4.2 Turn on timeout control

4.2.1 The first way

modify application.yml file , Add the following configuration

#  Set up  feign  Client timeout (OpenFeign The default support  ribbon ) 
ribbon:
#  The time taken to establish a connection , It is suitable for normal network conditions  ,  The time taken to connect the two ends 
   ReadTimeout:  5000
#  It refers to the time taken to read the available resources from the server after the connection is established 
   ConnectTimeout:  5000 

80 complete application.yml

server:
  port: 80

eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/
#  Set up  feign  Client timeout (OpenFeign The default support  ribbon )
ribbon:
  ReadTimeout: 5000 #  The time taken to establish a connection , It is suitable for normal network conditions  ,  The time taken to connect the two ends 
  ConnectionTimeout: 5000 #  It refers to the time taken to read the available resources from the server after the connection is established 

4.2.2 The second way ：

modify application.yml file , Add the following configuration

feign:
  client:
    config:
      CLOUD-PAYMENT-SERVICE:
        readTimeout: 5000
        connectTimeout: 5000

80 complete application.yml：

server:
  port: 80

spring:
  application:
    name: cloud-feign-consumer

eureka:
  client:
    register-with-eureka: true
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/

feign:
  client:
    config:
      CLOUD-PAYMENT-SERVICE:  # FeignClient The name of 
        readTimeout: 5000
        connectTimeout: 5000

Restart after adding 80 To test ：

4.3 Feign Other configurations for

from SpringCloud Edgware Start ,Feign Support the use of custom attributes Feign. For a named FeignClient（ For example FeignClient For the name of the feignName）,Feign The following configuration items are supported ：

feign:
  client:
    config:
      feignName:  #  Definition  FeignClient  The name of 
        readTimeout: 5000
        connectTimeout: 5000
        #  To configure  Feign  Log level of , It's equivalent to  Logger
        loggerLevel: FULL
        # Feign  Error decoder for , It's equivalent to  ErrorDecoder
        errorDecoder: com.example.SimpleErrorDecoder
        #  Configuration retry , It's equivalent to  Retryer
        retryer: com.example.SimpleRetryer
        #  Configure interceptors , It's equivalent to  RequestInterceptor
        requestInterceptors:
          - com.example.FooRequestInterceptor
          - com.example.BarRequestInterceptor
        decode404: false

• feignName：FeignClient The name of
• connectTimeout： The timeout for establishing a link
• readTimeout： Read timeout duration
• loggerLevel：Feign Log level of
• errorDecoder：Feign Error decoder for
• retryer： Configuration retry
• requestInterceptors： Add a request interceptor
• decode404： Configuration fusing is not handled 404 abnormal

4.4 Log printing function

In the development or operation phase, you often want to see Feign Logging of the request process , By default Feign Your log is not open . There are two ways to open ： One is through configuration yml Mode on , The other is to enable through the configuration class .

4.4.1 To configure application.yml

If you want to use attribute configuration to achieve logging effect , Only need application.yml Add the following to ：

feign:
  client:
    config:
      CLOUD-PAYMENT-SERVICE:  #  Definition  FeignClient  The name of 
        #  To configure  Feign  Log level of , It's equivalent to  Logger
        loggerLevel: FULL
        
logging:
  level:
    com.atguigu.springcloud.service.PaymentFeignService: debug

• loggin.level.xx: debug： feign At what level does the log monitor which interface
• feign.client.config.CLOUD_PAYMENT_SERVICE.loggerLevel： To configure Feign Log level of .

Feign There are four logging levels ：

• NONE【 Best performance , Suitable for production 】： Don't log anything （ The default value is ）
• BASIC【 Applicable to production environment tracking problems 】： Only the request method is recorded 、URL、 Response status code and execution time
• HEADERS： Record BASIC Level based , Recording requests and responses header
• FULL【 It is more suitable for positioning problems in development and test environment 】： Recording requests and responses header、body And metadata .

complete application.yml

server:
  port: 80

spring:
  application:
    name: cloud-feign-consumer

eureka:
  client:
    register-with-eureka: true
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/

feign:
  client:
    config:
      CLOUD-PAYMENT-SERVICE:  #  Definition  FeignClient  The name of 
        readTimeout: 5000
        connectTimeout: 5000
        #  To configure  Feign  Log level of , It's equivalent to  Logger
        loggerLevel: FULL


logging:
  level:
    com.atguigu.springcloud.service.PaymentFeignService: debug

4.4.2 Configuration class

1、 Create configuration class

@Configuration
public class FeignConfig {
    

    @Bean
    public Logger.Level feignLoggerLevel(){
    
        return Logger.Level.FULL;
    }
}

2、yml The configuration file enables the logging function

logging:
  level:
    com.atguigu.springcloud.service.PaymentFeignService: debug

complete application.yml：

server:
  port: 80

spring:
  application:
    name: cloud-feign-consumer

eureka:
  client:
    register-with-eureka: true
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/
#  Set up  feign  Client timeout (OpenFeign The default support  ribbon )
ribbon:
  ReadTimeout: 5000 #  The time taken to establish a connection , It is suitable for normal network conditions  ,  The time taken to connect the two ends 
  ConnectionTimeout: 5000 #  It refers to the time taken to read the available resources from the server after the connection is established 

logging:
  level:
    com.atguigu.springcloud.service.PaymentFeignService: debug  # feign  At what level does the log monitor which interface 

Start the test , visit http://localhost/consumer/payment/get/31