如何通过Ribbon实现负载均衡

由于Eureka依赖本身就自带Ribbon，故无需再添加依赖

@EnableEurekaClient
@SpringBootApplication
public class ScbrlWebApplication {
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(ScbrlWebApplication.class, args);
    }
}

· 只需要在RestTemplate添加@LoadBalanced注解即可实现默认轮询负载
· 注：restTemplate需在ScbrlWebApplication加载时将@Bean注入Spring容器

如何使RestTemplate请求自动添加请求头

· 添加自定义请求拦截器

/**
 * 模块:【RestTemplate请求拦截器】
 * <p>
 * 开发: Bruce.Liu By 2017/11/20 下午8:06 Create
 */
public class RestUserAgentInterceptor implements ClientHttpRequestInterceptor {
    /**
     * RestTemplate请求加上默认请求头（签名、时间轴）
     * @param request
     * @param body
     * @param execution
     * @return
     * @throws IOException
     */
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        HttpHeaders headers = request.getHeaders();
        String timestamp = System.currentTimeMillis()+"";
        headers.add("timestamp",timestamp);
        headers.add("sign", MD5Util.RestfulSign(timestamp,
                InetAddress.getLocalHost().getHostAddress()));
        return execution.execute(request, body);
    }
}

· RestTemplate 初始化Bean时 添加请求拦截器

@EnableEurekaClient
@SpringBootApplication
//@EnableFeignClients //暂未使用
@Slf4j
public class ScbrlWebApplication {
    ······略
    /**
     * 实例化restTemplate
     * 并使其拥有Ribbon负载均衡能力
     * @return
     */
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        HttpComponentsClientHttpRequestFactory httpRequestFactory = new HttpComponentsClientHttpRequestFactory();
        httpRequestFactory.setConnectionRequestTimeout(15);
        httpRequestFactory.setConnectTimeout(15);
        httpRequestFactory.setReadTimeout(15);
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.getMessageConverters()
                .add(0, new StringHttpMessageConverter(Charset.forName("UTF-8")));
        restTemplate.setInterceptors(Collections.singletonList(new RestUserAgentInterceptor()));
        return restTemplate;
    }
    ······略
}

大功告成，这样每次restTemplate请求都会进入RestUserAgentInterceptor，自动加上请求头信息