1、RibbonConsulAutoConfiguration
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties
@ConditionalOnConsulEnabled
@ConditionalOnBean(SpringClientFactory.class)
@ConditionalOnProperty(value = "spring.cloud.consul.ribbon.enabled",
matchIfMissing = true)
@AutoConfigureAfter(RibbonAutoConfiguration.class)
@RibbonClients(defaultConfiguration = ConsulRibbonClientConfiguration.class)
public class RibbonConsulAutoConfiguration {
}
2、RibbonAutoConfiguration
@Configuration
@Conditional(RibbonAutoConfiguration.RibbonClassesConditions.class)
@RibbonClients
@AutoConfigureAfter(
name = "org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration")
@AutoConfigureBefore({
LoadBalancerAutoConfiguration.class,
AsyncLoadBalancerAutoConfiguration.class })
@EnableConfigurationProperties({
RibbonEagerLoadProperties.class,
ServerIntrospectorProperties.class })
public class RibbonAutoConfiguration {
@Bean
public SpringClientFactory springClientFactory() {
SpringClientFactory factory = new SpringClientFactory();
factory.setConfigurations(this.configurations);
return factory;
}
@Bean
@ConditionalOnMissingBean(LoadBalancerClient.class)
public LoadBalancerClient loadBalancerClient() {
return new RibbonLoadBalancerClient(springClientFactory());
}
@Bean
@ConditionalOnClass(name = "org.springframework.retry.support.RetryTemplate")
@ConditionalOnMissingBean
public LoadBalancedRetryFactory loadBalancedRetryPolicyFactory(
final SpringClientFactory clientFactory) {
return new RibbonLoadBalancedRetryFactory(clientFactory);
}
@Bean
@ConditionalOnMissingBean
public PropertiesFactory propertiesFactory() {
return new PropertiesFactory();
}
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(HttpRequest.class)
@ConditionalOnRibbonRestClient
protected static class RibbonClientHttpRequestFactoryConfiguration {
@Autowired
private SpringClientFactory springClientFactory;
@Bean
public RestTemplateCustomizer restTemplateCustomizer(
final RibbonClientHttpRequestFactory ribbonClientHttpRequestFactory) {
return restTemplate -> restTemplate
.setRequestFactory(ribbonClientHttpRequestFactory);
}
@Bean
public RibbonClientHttpRequestFactory ribbonClientHttpRequestFactory() {
return new RibbonClientHttpRequestFactory(this.springClientFactory);
}
}
}
目的是初始化LoadBalancerClient。
3、LoadBalancerAutoConfiguration
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RestTemplate.class)
@ConditionalOnBean(LoadBalancerClient.class)
@EnableConfigurationProperties(LoadBalancerRetryProperties.class)
public class LoadBalancerAutoConfiguration {
@LoadBalanced
@Autowired(required = false)
private List<RestTemplate> restTemplates = Collections.emptyList();
@Autowired(required = false)
private List<LoadBalancerRequestTransformer> transformers = Collections.emptyList();
@Bean
public SmartInitializingSingleton loadBalancedRestTemplateInitializerDeprecated(// 示例1
ObjectProvider<List<RestTemplateCustomizer>> restTemplateCustomizers) {
//入参需要实例化RestTemplateCustomizer
return () -> restTemplateCustomizers.ifAvailable(customizers -> {
//调用SmartInitializingSingleton默认方法
for (RestTemplate restTemplate : LoadBalancerAutoConfiguration.this.restTemplates) {
for (RestTemplateCustomizer customizer : customizers) {
customizer.customize(restTemplate);// 对接口RestTemplateCustomizer抽象方法的调用
}
}
});
}
@Bean
@ConditionalOnMissingBean
public LoadBalancerRequestFactory loadBalancerRequestFactory(
LoadBalancerClient loadBalancerClient) {
return new LoadBalancerRequestFactory(loadBalancerClient, this.transformers);
}
@Configuration(proxyBeanMethods = false)
@ConditionalOnMissingClass("org.springframework.retry.support.RetryTemplate")
static class LoadBalancerInterceptorConfig {
@Bean
public LoadBalancerInterceptor ribbonInterceptor(
LoadBalancerClient loadBalancerClient,
LoadBalancerRequestFactory requestFactory) {
return new LoadBalancerInterceptor(loadBalancerClient, requestFactory);
}
@Bean
@ConditionalOnMissingBean
public RestTemplateCustomizer restTemplateCustomizer(//这种方式是实例化RestTemplateCustomizer实例 示例2
final LoadBalancerInterceptor loadBalancerInterceptor) {
return restTemplate -> {
// 对接口RestTemplateCustomizer中抽象方法的实现
List<ClientHttpRequestInterceptor> list = new ArrayList<>(
restTemplate.getInterceptors());
list.add(loadBalancerInterceptor);
restTemplate.setInterceptors(list);
};
}
}
}
- 该配置类的作用是对RestTemplate设置拦截器
LoadBalancerInterceptor。 - SmartInitializingSingleton类抽象方法调用时机为：DefaultListableBeanFactory#preInstantiateSingletons。【Trigger post-initialization callback for all applicable beans…】
- 示例1、示例2都是通过匿名内部类方式对bean进行实例化，同时通过lamada表达式实现接口的抽象方法。
4、服务发现
通过 RestTemplate#doExecute【ClientHttpRequest#execute】 中拦截器实现注册中心客户端的负载均衡。
4.1、InterceptingClientHttpRequest
class InterceptingClientHttpRequest extends AbstractBufferingClientHttpRequest {
private final List<ClientHttpRequestInterceptor> interceptors;
private class InterceptingRequestExecution implements ClientHttpRequestExecution {
private final Iterator<ClientHttpRequestInterceptor> iterator;
public InterceptingRequestExecution() {
this.iterator = interceptors.iterator();
}
public ClientHttpResponse execute(HttpRequest request, byte[] body) throws IOException {
if (this.iterator.hasNext()) {
ClientHttpRequestInterceptor nextInterceptor = this.iterator.next();
return nextInterceptor.intercept(request, body, this);
}else{
... }
}
}
}
4.2、LoadBalancerInterceptor
public ClientHttpResponse intercept(final HttpRequest request, final byte[] body,
final ClientHttpRequestExecution execution) throws IOException {
final URI originalUri = request.getURI();
String serviceName = originalUri.getHost();
return this.loadBalancer.execute(serviceName,
this.requestFactory.createRequest(request, body, execution));
}
4.3、RibbonLoadBalancerClient
public <T> T execute(String serviceId, LoadBalancerRequest<T> request, Object hint){
获取ILoadBalancer接口的某种负载均衡策略
ILoadBalancer loadBalancer = getLoadBalancer(serviceId);//servicedId是从restTemplate客户端的URL中获取得到
Server server = getServer(loadBalancer, hint);//利用默认的负载策略ZoneAwareLoadBalancer获取目标服务的IP、端口号等信息
RibbonServer ribbonServer = new RibbonServer(serviceId, server,
isSecure(server, serviceId),
serverIntrospector(serviceId).getMetadata(server));
return execute(serviceId, ribbonServer, request);
}
具体过程参考：服务发现