README.md

Spring Boot Starter OpenFeign

This library makes it easier to automatically use Feign.builder() to construct API interfaces with your custom components declared with a @FeignClient annotation. There is no any configures about Ribbon or Eureka for this library, just simply visits the APIs with the domain URL and path.

Artifacts

What's New?

1.2.0 - 25th January 2021

• Enhance the @FeignClient annotation customizations including fully configurable HTTP client, request encoder, response decoder, and error response decoder
• Enhance the properties file customizations including configurable logLevel and loggerType

1.1.3 - 9th January 2021

• Fix CustomErrorDecoder error and upgrade to compatible with feign ^10.7.3 ~10.12

Requirements

The following table shows the feign versions that are used by version of spring-boot-starter-openfeign:

spring-boot-starter-openfeign	feign
1.2.0 1.1.3	^10.7.3
1.1.2	10.7.2

Maven Configuration

Add the Maven dependency:

<dependency>
  <groupId>com.github.ethancommitpush</groupId>
  <artifactId>spring-boot-starter-openfeign</artifactId>
  <version>1.2.0</version>
</dependency>

<dependency>
  <groupId>io.github.openfeign</groupId>
  <artifactId>feign-core</artifactId>
  <version>10.7.3</version>
</dependency>

<dependency>
  <groupId>io.github.openfeign</groupId>
  <artifactId>feign-jackson</artifactId>
  <version>10.7.3</version>
</dependency>

<dependency>
  <groupId>io.github.openfeign</groupId>
  <artifactId>feign-httpclient</artifactId>
  <version>10.7.3</version>
</dependency>

<dependency>
  <groupId>io.github.openfeign</groupId>
  <artifactId>feign-slf4j</artifactId>
  <version>10.7.3</version>
</dependency>

Gradle

compile group: 'com.github.ethancommitpush', name: 'spring-boot-starter-openfeign', version: '1.2.0'
compile group: 'io.github.openfeign', name: 'feign-core', version: '10.7.3'
compile group: 'io.github.openfeign', name: 'feign-jackson', version: '10.7.3'
compile group: 'io.github.openfeign', name: 'feign-httpclient', version: '10.7.3'
compile group: 'io.github.openfeign', name: 'feign-slf4j', version: '10.7.3'

Basic Usage

• Use @FeignClient to declare custom components to be generated as API interfaces:

package example.client;

@Headers({"Content-Type: application/json"})
@FeignClient(url = "${postman-echo.domain}")
public interface PostmanEchoClient {

    @RequestLine("GET /time/object?timestamp={timestamp}")
    TimeObjectGetRespDTO getTimeObject(@Param("timestamp") String timestamp);

}

• application.yml Properties configuration:

feign:
  # Set up log level for feign behaviors
  log-level: BASIC
  # Set up logger type to append logs
  logger-type: SLF4J
  # Packages to be scanned for interfaces declared with @FeignClient
  base-packages: example.client

postman-echo:
  # The base url for your API interface, e. g. @FeignClient(url = "${postman-echo.domain}")
  domain: https://postman-echo.com

• Use @Autowired to autowire the API interfaces and further use it:

    @Autowired
    private PostmanEchoClient postmanEchoClient;

    public void run(String... args) throws Exception {
        TimeObjectGetRespDTO respDTO1 = postmanEchoClient.getTimeObject("2016-10-10");
        log.info("{}", respDTO1);
    }

Examples

Look up the example.

Advanced Usage

• The following table shows the components and iots default bean names which were used by spring-boot-starter-openfeign. If you want to customize some components of them, just implement the component interfaces and delare them as beans:

Component Type	Default Bean Name	Component Interface
HTTP Client	feignClient	feign.Client
Request Encoder	feignEncoder	feign.codec.Encoder
Response Decoder	feignDecoder	feign.codec.Decoder
Error Response Decoder	feignErrorDecoder	feign.codec.ErrorDecoder

• Use @Configuration to declare a default decoder for all API interfaces with @FeignClient annotation:

@Configuration
@Slf4j
public class FeignConfig {
    @Bean
    public Decoder feignDecoder() {
        return new JacksonDecoder() {
            @Override
            public Object decode(Response response, Type type) throws IOException {
                log.info("inside overridden feignDecoder.decoder()");
                return super.decode(response, type);
            }
        };
    }
}

• Use @Configuration to declare a custom decoder, and assign to certain API interface with @FeignClient annotation:

@Configuration
@Slf4j
public class FeignConfig {
    @Bean
    public Decoder myDecoder() {
        return new JacksonDecoder() {
            @Override
            public Object decode(Response response, Type type) throws IOException {
                log.info("inside myDecoder.decoder()");
                return super.decode(response, type);
            }
        };
    }
}

@FeignClient(url = "${postman-echo.domain}", decoder = "myDecoder")
public interface PostmanEchoClient2 {

    @RequestLine("POST /post?foo1={foo1}&foo2={foo2}")
    PostPostRespDTO postPost(@Param("foo1") String foo1, @Param("foo2") String foo2);

}

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