java 代码实现灰度发布

以下是Java代码实现灰度发布的示例：

1. 在pom.xml中添加依赖：

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-loadbalancer</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-alibaba-nacos-discovery</artifactId>
    </dependency>
</dependencies>

2. 在application.properties中配置Nacos的地址和服务名：

spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848
spring.cloud.nacos.discovery.service=service-name

3. 创建一个Controller类作为测试入口：

@RestController
public class TestController {
    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/test")
    public String test() {
        String result = restTemplate.getForObject("http://service-name/test", String.class);
        return "test result: " + result;
    }
}

4. 创建一个灰度发布规则的实现类，例如按照IP地址的规则：

@Component
public class IpGrayRule implements GrayRule {
    private static final List<String> GRAY_IPS = Arrays.asList("192.168.0.1", "192.168.0.2");

    @Override
    public boolean isGray() {
        String currentIp = getCurrentIp();
        return GRAY_IPS.contains(currentIp);
    }

    private String getCurrentIp() {
        // 实现获取当前IP地址的逻辑
        return "192.168.0.1";
    }
}

5. 创建一个LoadBalancerClient的实现类，用于根据灰度发布规则选择特定的服务器：

@Component
public class GrayLoadBalancer implements LoadBalancerClient {
    @Autowired
    private GrayRule grayRule;

    @Autowired
    private LoadBalancerClient delegate;

    @Override
    public ServiceInstance choose(String serviceId) {
        if (grayRule.isGray()) {
            List<ServiceInstance> grayInstances = getGrayInstances(serviceId);
            if (!grayInstances.isEmpty()) {
                return grayInstances.get(0);
            }
        }
        return delegate.choose(serviceId);
    }

    private List<ServiceInstance> getGrayInstances(String serviceId) {
        // 根据特定的规则获取灰度发布的服务器列表
        List<ServiceInstance> allInstances = delegate.getInstances(serviceId);
        List<ServiceInstance> grayInstances = new ArrayList<>();
        for (ServiceInstance instance : allInstances) {
            String instanceIp = instance.getUri().getHost();
            if (grayRule.isGray(instanceIp)) {
                grayInstances.add(instance);
            }
        }
        return grayInstances;
    }
}

6. 创建一个RestTemplate的Bean，使用LoadBalancerClient的实现类作为负载均衡器：

@Configuration
public class RestTemplateConfig {
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(GrayLoadBalancer grayLoadBalancer) {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setInterceptors(Collections.singletonList(new GrayRequestInterceptor(grayLoadBalancer)));
        return restTemplate;
    }
}

7. 创建一个RestTemplate的拦截器，用于在请求头中添加特定的标识符，例如X-Gray-Enabled：

public class GrayRequestInterceptor implements ClientHttpRequestInterceptor {
    private GrayLoadBalancer grayLoadBalancer;

    public GrayRequestInterceptor(GrayLoadBalancer grayLoadBalancer) {
        this.grayLoadBalancer = grayLoadBalancer;
    }

    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution)
            throws IOException {
        if (grayLoadBalancer.isGray()) {
            HttpHeaders headers = request.getHeaders();
            headers.add("X-Gray-Enabled", "true");
        }
        return execution.execute(request, body);
    }
}

8. 在服务端实现类中，根据请求头中的标识符来判断是否启用灰度发布：

@RestController
public class TestController {
    @GetMapping("/test")
    public String test(HttpServletRequest request) {
        boolean isGrayEnabled = Boolean.parseBoolean(request.getHeader("X-Gray-Enabled"));
        if (isGrayEnabled) {
            return "gray test";
        } else {
            return "normal test";
        }
    }
}

这样，就完成了基于Nacos和Spring Cloud LoadBalancer实现灰度发布的Java代码示例。需要注意的是，在实际应用中，还需要考虑更多的因素，例如负载均衡策略、数据迁移等，需要根据具体情况进行实现和调整。