Change in contract for @LoadBalanced
Users now need to create their own bean and qualify it, and Spring Cloud will customize it (instead of providing the @Bean itself). This is much better for users, since they remain in control of the bean declarations, and can choose which one (if any) is @Primary. It's a breaking change for some apps (if they rely on a @LoadBalanced RestTemplate being automatically injected).
This commit is contained in:
Dave Syer
@@ -318,15 +318,21 @@ for details of how the `RestTemplate` is set up.
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If you want a `RestTemplate` that is not load balanced, create a `RestTemplate`
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bean and inject it as normal. To access the load balanced `RestTemplate use
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the provided `@LoadBalanced` `Qualifier`.
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the `@LoadBalanced` qualifier when you create your `@Bean`.
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IMPORTANT: Notice the `@Primary` annotation on the plain `RestTemplate` declaration.
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IMPORTANT: Notice the `@Primary` annotation on the plain `RestTemplate` declaration in the example below, to disambiguate the unqualified `@Autowired` injection.
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[source,java,indent=0]
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----
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@Configuration
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public class MyConfiguration {
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@LoadBalanced
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@Bean
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RestTemplate loadBalanced() {
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return new RestTemplate();
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}
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@Primary
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@Bean
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RestTemplate restTemplate() {
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@@ -17,8 +17,11 @@
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package org.springframework.cloud.client.loadbalancer;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import org.springframework.beans.factory.SmartInitializingSingleton;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
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import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
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import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
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@@ -38,15 +41,23 @@ import org.springframework.web.client.RestTemplate;
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@ConditionalOnBean(LoadBalancerClient.class)
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public class LoadBalancerAutoConfiguration {
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@Bean
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@LoadBalanced
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public RestTemplate loadBalancedRestTemplate(
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List<RestTemplateCustomizer> customizers) {
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RestTemplate restTemplate = new RestTemplate();
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for (RestTemplateCustomizer customizer : customizers) {
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customizer.customize(restTemplate);
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}
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return restTemplate;
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@Autowired(required = false)
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private List<RestTemplate> restTemplates = Collections.emptyList();
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@Bean
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public SmartInitializingSingleton loadBalancedRestTemplateInitializer(
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final List<RestTemplateCustomizer> customizers) {
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return new SmartInitializingSingleton() {
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@Override
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public void afterSingletonsInstantiated() {
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for (RestTemplate restTemplate : LoadBalancerAutoConfiguration.this.restTemplates) {
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for (RestTemplateCustomizer customizer : customizers) {
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customizer.customize(restTemplate);
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}
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}
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}
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};
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}
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@Bean
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@@ -1,20 +1,11 @@
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package org.springframework.cloud.client.loadbalancer;
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import static org.hamcrest.Matchers.empty;
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import static org.hamcrest.Matchers.hasSize;
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import static org.hamcrest.Matchers.instanceOf;
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import static org.hamcrest.Matchers.is;
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import static org.hamcrest.Matchers.notNullValue;
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import static org.junit.Assert.assertThat;
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import java.net.URI;
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import java.util.Collection;
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import java.util.List;
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import java.util.Map;
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import java.util.Random;
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import lombok.SneakyThrows;
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import org.junit.Test;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.boot.builder.SpringApplicationBuilder;
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@@ -27,107 +18,132 @@ import org.springframework.context.annotation.Primary;
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import org.springframework.http.client.ClientHttpRequestInterceptor;
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import org.springframework.web.client.RestTemplate;
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import static org.hamcrest.Matchers.empty;
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import static org.hamcrest.Matchers.hasSize;
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import static org.hamcrest.Matchers.instanceOf;
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import static org.hamcrest.Matchers.is;
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import static org.hamcrest.Matchers.notNullValue;
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import static org.junit.Assert.assertThat;
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import lombok.SneakyThrows;
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/**
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* @author Spencer Gibb
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*/
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public class LoadBalancerAutoConfigurationTests {
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@Test
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public void restTemplateGetsLoadBalancerInterceptor() {
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ConfigurableApplicationContext context = init(OneRestTemplate.class);
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final Map<String, RestTemplate> restTemplates = context.getBeansOfType(RestTemplate.class);
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@Test
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public void restTemplateGetsLoadBalancerInterceptor() {
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ConfigurableApplicationContext context = init(OneRestTemplate.class);
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final Map<String, RestTemplate> restTemplates = context
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.getBeansOfType(RestTemplate.class);
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assertThat(restTemplates, is(notNullValue()));
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assertThat(restTemplates.values(), hasSize(1));
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RestTemplate restTemplate = restTemplates.values().iterator().next();
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assertThat(restTemplate, is(notNullValue()));
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assertThat(restTemplates, is(notNullValue()));
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assertThat(restTemplates.values(), hasSize(1));
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RestTemplate restTemplate = restTemplates.values().iterator().next();
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assertThat(restTemplate, is(notNullValue()));
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assertLoadBalanced(restTemplate);
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}
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assertLoadBalanced(restTemplate);
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}
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protected void assertLoadBalanced(RestTemplate restTemplate) {
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List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
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assertThat(interceptors, hasSize(1));
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ClientHttpRequestInterceptor interceptor = interceptors.get(0);
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assertThat(interceptor, is(instanceOf(LoadBalancerInterceptor.class)));
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}
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protected void assertLoadBalanced(RestTemplate restTemplate) {
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List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
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assertThat(interceptors, hasSize(1));
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ClientHttpRequestInterceptor interceptor = interceptors.get(0);
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assertThat(interceptor, is(instanceOf(LoadBalancerInterceptor.class)));
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}
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@Test
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public void multipleRestTemplates() {
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ConfigurableApplicationContext context = init(TwoRestTemplates.class);
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final Map<String, RestTemplate> restTemplates = context.getBeansOfType(RestTemplate.class);
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@Test
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public void multipleRestTemplates() {
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ConfigurableApplicationContext context = init(TwoRestTemplates.class);
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final Map<String, RestTemplate> restTemplates = context
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.getBeansOfType(RestTemplate.class);
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assertThat(restTemplates, is(notNullValue()));
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Collection<RestTemplate> templates = restTemplates.values();
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assertThat(templates, hasSize(2));
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assertThat(restTemplates, is(notNullValue()));
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Collection<RestTemplate> templates = restTemplates.values();
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assertThat(templates, hasSize(2));
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TwoRestTemplates.Two two = context.getBean(TwoRestTemplates.Two.class);
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TwoRestTemplates.Two two = context.getBean(TwoRestTemplates.Two.class);
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assertThat(two.loadBalanced, is(notNullValue()));
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assertLoadBalanced(two.loadBalanced);
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assertThat(two.loadBalanced, is(notNullValue()));
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assertLoadBalanced(two.loadBalanced);
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assertThat(two.nonLoadBalanced, is(notNullValue()));
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assertThat(two.nonLoadBalanced.getInterceptors(), is(empty()));
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}
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assertThat(two.nonLoadBalanced, is(notNullValue()));
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assertThat(two.nonLoadBalanced.getInterceptors(), is(empty()));
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}
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protected ConfigurableApplicationContext init(Class<?> config) {
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return new SpringApplicationBuilder().web(false)
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.properties("spring.aop.proxyTargetClass=true")
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.sources(config, LoadBalancerAutoConfiguration.class).run();
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}
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protected ConfigurableApplicationContext init(Class<?> config) {
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return new SpringApplicationBuilder().web(false).sources(config, LoadBalancerAutoConfiguration.class).run();
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}
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@Configuration
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protected static class OneRestTemplate {
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@Configuration
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protected static class OneRestTemplate {
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@LoadBalanced
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@Bean
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RestTemplate loadBalancedRestTemplate() {
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return new RestTemplate();
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}
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@Bean
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LoadBalancerClient loadBalancerClient() {
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return new NoopLoadBalancerClient();
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}
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@Bean
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LoadBalancerClient loadBalancerClient() {
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return new NoopLoadBalancerClient();
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}
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}
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}
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@Configuration
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protected static class TwoRestTemplates {
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@Configuration
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protected static class TwoRestTemplates {
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@Primary
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@Bean
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RestTemplate restTemplate() {
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return new RestTemplate();
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}
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@Primary
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@Bean
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RestTemplate restTemplate() {
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return new RestTemplate();
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}
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@Bean
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LoadBalancerClient loadBalancerClient() {
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return new NoopLoadBalancerClient();
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}
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@LoadBalanced
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@Bean
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RestTemplate loadBalancedRestTemplate() {
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return new RestTemplate();
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}
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@Configuration
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protected static class Two {
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@Autowired
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RestTemplate nonLoadBalanced;
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@Bean
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LoadBalancerClient loadBalancerClient() {
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return new NoopLoadBalancerClient();
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}
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@Autowired
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@LoadBalanced
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RestTemplate loadBalanced;
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}
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@Configuration
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protected static class Two {
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@Autowired
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RestTemplate nonLoadBalanced;
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}
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@Autowired
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@LoadBalanced
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RestTemplate loadBalanced;
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}
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private static class NoopLoadBalancerClient implements LoadBalancerClient {
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private final Random random = new Random();
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}
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@Override
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public ServiceInstance choose(String serviceId) {
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return new DefaultServiceInstance(serviceId, serviceId, random.nextInt(40000), false);
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}
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private static class NoopLoadBalancerClient implements LoadBalancerClient {
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private final Random random = new Random();
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@Override
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@SneakyThrows
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public <T> T execute(String serviceId, LoadBalancerRequest<T> request) {
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return request.apply(choose(serviceId));
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}
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@Override
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public ServiceInstance choose(String serviceId) {
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return new DefaultServiceInstance(serviceId, serviceId,
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this.random.nextInt(40000), false);
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}
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@Override
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public URI reconstructURI(ServiceInstance instance, URI original) {
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return DefaultServiceInstance.getUri(instance);
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}
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}
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@Override
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@SneakyThrows
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public <T> T execute(String serviceId, LoadBalancerRequest<T> request) {
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return request.apply(choose(serviceId));
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}
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@Override
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public URI reconstructURI(ServiceInstance instance, URI original) {
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return DefaultServiceInstance.getUri(instance);
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}
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}
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}
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