import java.util.concurrent.CompletableFuture;
public interface DemoService {
    /**
     * 同步处理的服务方法
     * @param name
     * @return
     */
    String sayHello(String name);

    /**
     * 用于异步处理的服务方法
     * @param name
     * @return
     */
    default CompletableFuture<String> sayHelloAsync(String name) {
        return CompletableFuture.completedFuture(sayHello(name));
    }
}

服务实现类如下:

import org.apache.dubbo.rpc.RpcContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.CompletableFuture;

public class DemoServiceImpl implements DemoService {
    private static final Logger logger = LoggerFactory.getLogger(DemoServiceImpl.class);

    @Override
    public String sayHello(String name) {
        logger.info("Hello " + name + ", request from consumer: " + RpcContext.getServiceContext().getRemoteAddress());
        return "Hello " + name + ", response from provider: " + RpcContext.getServiceContext().getLocalAddress();
    }

    @Override
    public CompletableFuture<String> sayHelloAsync(String name) {
        return null;
    }

}

package link.elastic.dubbo.consumer;

import link.elastic.dubbo.entity.DemoService;
import org.apache.dubbo.common.constants.CommonConstants;
import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.MetadataReportConfig;
import org.apache.dubbo.config.ProtocolConfig;
import org.apache.dubbo.config.ReferenceConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.apache.dubbo.config.bootstrap.DubboBootstrap;
import org.apache.dubbo.rpc.service.GenericService;

public class ConsumerApplication {
    public static void main(String[] args) {
            runWithBootstrap();
    }
    private static void runWithBootstrap() {
        ReferenceConfig<DemoService> reference = new ReferenceConfig<>();
        reference.setInterface(DemoService.class);
        reference.setGeneric("true");
        reference.setProtocol("");

        DubboBootstrap bootstrap = DubboBootstrap.getInstance();
        ApplicationConfig applicationConfig = new ApplicationConfig("dubbo-demo-api-consumer");
        applicationConfig.setQosEnable(false);
        applicationConfig.setQosPort(-1);
        bootstrap.application(applicationConfig)
            .registry(new RegistryConfig("zookeeper://8.131.79.126:2181"))
            .protocol(new ProtocolConfig(CommonConstants.DUBBO, -1))
            .reference(reference)
            .start();

        DemoService demoService = bootstrap.getCache().get(reference);
        String message = demoService.sayHello("dubbo");
        System.out.println(message);

        // generic invoke
        GenericService genericService = (GenericService) demoService;
        Object genericInvokeResult = genericService.$invoke("sayHello", new String[]{String.class.getName()},
            new Object[]{"dubbo generic invoke"});
        System.out.println(genericInvokeResult);
    }
}