OpenFeign

Introduction to the

Originally called Feign, the declarative service invocation component that the Spring Cloud team developed on top of Netflix Feign as it went open-source

HelloWorld

• 1. Prepare the provider

Make sure nacOS is started and learn nacOS by clicking juejin.cn/post/700294…

Then create the SpringBoot project Provider, which uses NACOS as the registry.

Introduction of depend on

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        <version>2.2.4. RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>
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application.properties

spring.application.name=provider
spring.cloud.nacos.discovery.server-addr=192.168.189.101:8848
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Defines the interface

@RestController
public class TestController {
    @Value("${server.port}")
    Integer port;

    @GetMapping("/hello")
    public String hello(a) {
        return "hello:"+ port; }}Copy the code

Once packaged, start the project with two separate ports

• 2. Ready to consumer

Create a New SpringBoot project consumer

Introduction of depend on

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
        <version>2.2.8. RELEASE</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        <version>2.2.4. RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>
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application.properties

spring.application.name=consumer
server.port=8083
spring.cloud.nacos.discovery.server-addr=192.168.189.101:8848
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Start the class

• 1. Enable the openFeign configuration
• 2. Define the RestTemplate to simulate load balancing

@SpringBootApplication
@EnableFeignClients
public class ConsumerApplication {

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

    @LoadBalanced
    @Bean
    RestTemplate restTemplate(a) {
        return newRestTemplate(); }}Copy the code

Define the service

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

@FeignClient("provider") // The argument is the provider's spring.application.name
public interface ConsumerService {
    @GetMapping("/hello")
    String hello(a); // The method name is optional
}
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Define the controller

@RestController
public class ConsumerController {
    @Autowired
    ConsumerService service;

    @GetMapping("/hello")
    public String hello(a) {
        returnservice.hello(); }}Copy the code

After starting the project, test by visiting localhost:8083/ Hello several times

Parameter passing

• 1. Parameters must be bound with parameter names
• 2. If the parameter is passed through the header, the Chinese characters must be transcoded

Continue adding interfaces using the provider

@RestController
public class TestController {
    @Value("${server.port}")
    Integer port;

    @GetMapping("/hello")
    public String hello(a) {
        return "hello:" + port;
    }

    @PostMapping("/hello2")
    public String hello2(String name) {
        return name;
    }

    @PutMapping("/hello3")
    public User hello3(@RequestBody User user) {
        return user;
    }

    @DeleteMapping("/hello4/{id}")
    public String hello4(@PathVariable int id) {
        return "delete : "+ id; }}Copy the code

Repackage and run separately

The consumer’s service continues to define the interface, and the key-value parameter must specify a name

@FeignClient("provider")
public interface ConsumerService {
    @GetMapping("/hello")
    String hello(a); // The method name is optional

    @PostMapping("/hello2")
    String hello2(@RequestParam("name") String name);

    @PutMapping("/hello3")
    User hello3(@RequestBody User user);

    @DeleteMapping("/hello4/{id}")
    String hello4(@PathVariable int id);
}
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The Consumer controller continues to define the interface

@RestController
public class ConsumerController {
    @Autowired
    ConsumerService service;

    @GetMapping("/hello")
    public String hello(a) {
        return service.hello();
    }

    @PostMapping("/hello2")
    public String hello2(String name) {
        return service.hello2(name);
    }

    @PutMapping("/hello3")
    public User hello3(@RequestBody User user) {
        return service.hello3(user);
    }

    @DeleteMapping("/hello4/{id}")
    public String hello4(@PathVariable int id) {
        returnservice.hello4(id); }}Copy the code

Start Consumer to complete the test access