SpringCloud Alibaba 从零学习(3)—服务调用

1. 创建可调用接口

在provider项目里创建controller层

@RestController
public class ProviderController {
    //SPEL
    @Value("${server.port}")
    private String port;
    @GetMapping("/index")
    public String index(){
        return this.port;
    }
}

2. 创建调用接口

在consumer创建调用接口

package com.jili.controller;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;
@RestController
@Slf4j
public class ConsumerController {
    //自动装载
    @Autowired
    private DiscoveryClient discoveryClient;
    @Autowired
    private RestTemplate restTemplate;
    @GetMapping("/instances")
    public List<ServiceInstance> instance(){
        List<ServiceInstance> provider = this.discoveryClient.getInstances("provider");
        return  provider;
    }
    @GetMapping("/index")
    public String index(){
        //调用provider服务的index的方法
        //1.找到provider实例
        List<ServiceInstance> list = this.discoveryClient.getInstances("provider");
        int index = ThreadLocalRandom.current().nextInt(list.size());
        ServiceInstance serviceInstance = list.get(index);
        String url = serviceInstance.getUri()+ "/index";
        //2.调用
        log.info("调用端口：{}",serviceInstance.getPort());
        return "调用了端口为："+serviceInstance.getPort()+"的服务，返回结果为："+this.restTemplate.getForObject(url,String.class)+"地址为："+url;
    }
}

通过restTemplate来访问nacos实例中provider服务的接口来模拟服务调用

由于restTemplate没有注入的问题，可以创建配置类来注入

package com.jili.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
@Configuration
public class ConsumerConfig {
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

也可以在启动类里直接注入，如：

3.效果

ps：为什么可以在*启动类直接注入？

@SpringBootApplication注解里包含了
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan

而@SpringBootConfiguration本质上也就是@Configuration~