22. Spring cloud - using feign to call service interface? Java version of spring cloud + springboot + uniapp + Vue B2B2C micro Service Mall micro service e-commerce live delivery source code

Springcloud Cloud Architecture 2021-04-16 18:33:06
spring cloud using feign service

JAVA How to do interface calls in a project ?


HttpClient yes Apache Jakarta Common Sub projects under , To provide efficient 、 Abreast of the times 、 Feature rich support Http Client programming toolkit for protocol , And it supports HTTP The latest version of the agreement and recommendations .

HttpClient Compared with tradition JDK Self contained URLConnection, Improved ease of use and flexibility , Make the client send HTTP It's easier to ask , Improved development efficiency .


An open source project to handle network requests , It's the most popular lightweight framework in Android , from Square The company contributed , Used in substitution HttpUrlConnection and Apache HttpClient.OkHttp Have a simple API、 Efficient performance , And support a variety of protocols (HTTP/2 and SPDY).


HttpURLConnection yes  Java  Standard class , It is inherited from URLConnection, Can be used to send GET request 、POST request .HttpURLConnection It's complicated to use , Unlike HttpClient That's easy to use .


RestTemplate yes  Spring  Provided for access Rest Client of service ,RestTemplate Provides a variety of convenient remote access HTTP Method of service , Can greatly improve the writing efficiency of the client .

The above are the most common methods to call the interface , The method we're going to introduce next is simpler than the one above 、 convenient , It is Feign.

Feign It's a declarative one REST client , It can make REST It's easier to call .Feign For HTTP Requested template , By writing simple interfaces and inserting annotations , You can define HTTP Requested parameters 、 Format 、 Address and other information .

and Feign It'll be a complete agent HTTP request , We only need to call it like a method to complete the service request and related processing .

Spring Cloud  Yes Feign It was packaged , To support SpringMVC Standard notes and HttpMessageConverters.Feign It can be done with Eureka and Ribbon Combined to support load balancing .

stay Spring Cloud In the integration Feign

stay Spring Cloud In the integration Feign The steps are quite simple , First of all, join Feign Dependence , The code is as follows .


Add... To the startup class @EnableFeignClients annotation , If your Feign The interface definition is not in the same package name as your startup class , You also need to make a package name to scan @EnableFeignClients(basePackages=“com.fangjia.api.client”), The code is as follows .

@EnableFeignClients(basePackages = "com.fangjia.api.client")
public class FshSubstitutionServiceApplication {
public static void main(String[] args) {
SpringApplication.run(FshSubstitutionServiceApplication.class, args);

Use Feign Call interface

Define a Feign The client of , In the form of interfaces , The code is as follows .

@FeignClient(value = "eureka-client-user-service")
public interface UserRemoteClient {
String hello();

First of all, let's look at the interface @FeignClient annotation . This annotation ID is currently a Feign The client of ,value Property is the corresponding service name , Which service interface do you need to call .

When defining a method, you can directly copy the definition of the interface , Of course, there is another way , That is to extract the interface and define it separately , And then in Controller Implementation interface in .

The interface is also implemented in the calling client , So as to achieve the purpose of interface sharing . My practice here is not shared , That is to create a separate API Client Public projects in China , Convention based patterns , Every time you write an interface, you need to write a calling Client, Make it public in the back jar, So no matter which project needs to call the interface , Just bring in a common interface SDK jar that will do , There's no need to redefine it .

After definition, it can be directly injected through UserRemoteClient To call , It's like calling local methods for developers .

Next, use Feign To call /user/hello Interface , The code is as follows .

private UserRemoteClient userRemoteClient;
public String callHello() {
//return restTemplate.getForObject("http://localhost:8083/house/hello",String.class);
//String result = restTemplate.getForObject("http://eureka-client-user-service/user/hello",String.class);
String result = userRemoteClient.hello();
System.out.println(" The results :" + result);
return result;

By comparing with the commented code, we can see that , The way we call it is getting simpler and simpler , From the designated address , Go back through Eureka To call , Up to now, it can be called directly by defining the interface .

Recommended cloth type Micro Service Mall

本文为[Springcloud Cloud Architecture]所创,转载请带上原文链接,感谢

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