动态创建FeignClient调用

根据实际情况，动态创建FeignClient进行远程调用

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.netflix.feign.FeignContext;
import org.springframework.stereotype.Component;

import feign.Client;
import feign.Contract;
import feign.Feign;
import feign.codec.Decoder;
import feign.codec.Encoder;
import feign.codec.ErrorDecoder;

/**
 * 
 * @author 
 * @date 2021/02/23
 */
@Component
// @Import(FeignClientsConfiguration.class)
public class TestFoo {

    Decoder decoder;
    Encoder encoder;
    Client client;
    Contract contract;
    ErrorDecoder errorDecoder;

    FeignContext context;

    public TestClientInterface testClient;
    
    /**
     * 需要开启 @Import(FeignClientsConfiguration.class)
     * @param client
     * @param deocder
     * @param encoder
     * @param contract
     * @param errorDecoder
     */
    @Autowired
    public TestFoo(Client client,Decoder deocder,Encoder encoder,Contract contract,ErrorDecoder errorDecoder) {
        this.decoder = deocder;
        this.encoder = encoder;
        this.errorDecoder = errorDecoder;
        this.contract = contract;
        this.client = client;
        this.testClient = Feign.builder().client(client).encoder(encoder).decoder(decoder).errorDecoder(errorDecoder)
            .contract(contract).target(TestClientInterface.class, "http://TEST-SERVICE");
    }
    

    public TestFoo(FeignContext context) {
        this.context = context;
        this.decoder = context.getInstance("TEST-SERVICE", Decoder.class);
        this.encoder = context.getInstance("TEST-SERVICE", Encoder.class);
        this.errorDecoder = context.getInstance("TEST-SERVICE", ErrorDecoder.class);
        this.contract = context.getInstance("TEST-SERVICE", Contract.class);
        this.client = context.getInstance("TEST-SERVICE", Client.class);
        this.testClient = Feign.builder().client(client).encoder(encoder).decoder(decoder).errorDecoder(errorDecoder)
            .contract(contract).target(TestClientInterface.class, "http://TEST-SERVICE");
    }

}

/**
 * 
 * @author
 * @date 2021/02/23
 */
@Component
public class DynamicFeignService {
    private static final Map<String, TestClientInterface> FEIGN_CLIENT_CACHE = Maps.newConcurrentMap();
    FeignContext context;

    public DynamicFeignService(FeignContext context) {
        this.context = context;
    }

    public synchronized TestClientInterface getFeignClientByServiceName(String serviceName) {
        return FEIGN_CLIENT_CACHE.computeIfAbsent(serviceName, (sn) -> {
            Decoder decoder = context.getInstance(serviceName, Decoder.class);
            Encoder encoder = context.getInstance(serviceName, Encoder.class);
            Contract contract = context.getInstance(serviceName, Contract.class);
            Client client = context.getInstance(serviceName, Client.class);
            ErrorDecoder errorDecoder = context.getInstance(serviceName, ErrorDecoder.class);

            return Feign.builder()
                .client(client)
                .encoder(encoder)
                .decoder(decoder)
                .errorDecoder(errorDecoder)
                .contract(contract)
                .target(TestClientInterface.class, "http://" + sn);
        });
    }
}