替换OpenFeign，Spring 新版本自带的 HTTP 客户端工具

原文链接：替换OpenFeign，Spring 新版本自带的 HTTP 客户端工具来了！

声明式Http接口

声明性 HTTP 接口可以让你像定义Java接口那样定义HTTP服务，用法和你平时写Controller中方法完全一致。

一、引入

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- For reactive support -->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

二、支持的注解类型

@HttpExchange：是用于指定 HTTP 端点的通用注释。在接口级别使用时，它适用于所有方法。
@GetExchange：为 HTTP GET请求指定@HttpExchange。
@PostExchange：为 HTTP POST请求指定@HttpExchange。
@PutExchange：为 HTTP PUT请求指定@HttpExchange。
@DeleteExchange：为 HTTP DELETE请求指定@HttpExchange。
@PatchExchange：为 HTTP PATCH请求指定@HttpExchange。

三、参数和返回值

四、示例

1.构建HttpServiceProxyFactory

import com.fasterxml.jackson.databind.ObjectMapper;
import com.howtodoinjava.app.web.UserClient;
import lombok.SneakyThrows;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.reactive.function.client.WebClient;
import org.springframework.web.reactive.function.client.support.WebClientAdapter;
import org.springframework.web.service.invoker.HttpServiceProxyFactory;
@Configuration
public class WebConfig {
  @Bean
  WebClient webClient(ObjectMapper objectMapper) {
    return WebClient.builder()
        .baseUrl("https://jsonplaceholder.typicode.com/")
        .build();
  }
  @SneakyThrows
  @Bean
  UserClient postClient(WebClient webClient) {
    HttpServiceProxyFactory httpServiceProxyFactory =
        HttpServiceProxyFactory.builder(WebClientAdapter.forClient(webClient))
            .build();
    return httpServiceProxyFactory.createClient(UserClient.class);
  }
}

2.接口

实体类

public class User {

    private int id;

    private String username;

    private String password;
  
   // 省略

}

接口

import com.howtodoinjava.app.model.User;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.service.annotation.DeleteExchange;
import org.springframework.web.service.annotation.GetExchange;
import org.springframework.web.service.annotation.HttpExchange;
import org.springframework.web.service.annotation.PostExchange;
import org.springframework.web.service.annotation.PutExchange;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
@HttpExchange(url = "/users", accept = "application/json", contentType = "application/json")
public interface UserClient {
  @GetExchange("/")
  Flux<User> getAll();
  @GetExchange("/{id}")
  Mono<User> getById(@PathVariable("id") Long id);
  @PostExchange("/")
  Mono<ResponseEntity<Void>> save(@RequestBody User user);
  @PutExchange("/{id}")
  Mono<ResponseEntity<Void>> update(@PathVariable Long id, @RequestBody User user);
  @DeleteExchange("/{id}")
  Mono<ResponseEntity<Void>> delete(@PathVariable Long id);

调用

@Autowired
UserClient userClient;
//Get All Users
userClient.getAll().subscribe(
    data -> log.info("User: {}", data)
);
//Get User By Id
userClient.getById(1L).subscribe(
    data -> log.info("User: {}", data)
);
//Create a New User
userClient.save(new User(null, "Lokesh", "lokesh", "admin@email.com"))
    .subscribe(
        data -> log.info("User: {}", data)
    );
//Delete User By Id
userClient.delete(1L).subscribe(
    data -> log.info("User: {}", data)
);