fallback support factoryBean (#3135)

spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-sentinel/src/main/java/com/alibaba/cloud/sentinel/feign/SentinelFeign.java

@@ -27,6 +27,7 @@ import feign.InvocationHandlerFactory;
 import feign.Target;
 
 import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.cloud.openfeign.FallbackFactory;
 import org.springframework.cloud.openfeign.FeignClientFactory;
@@ -41,6 +42,7 @@ import org.springframework.util.StringUtils;
  * {@link Feign.Builder}.
  *
  * @author <a href="mailto:fangjian0423@gmail.com">Jim</a>
+ * @author 黄学敏（huangxuemin)
  */
 public final class SentinelFeign {
 
@@ -137,6 +139,16 @@ public final class SentinelFeign {
 								"No %s instance of type %s found for feign client %s",
 								type, fallbackType, name));
 					}
+					// when fallback is a FactoryBean, should determine the type of instance
+					if (fallbackInstance instanceof FactoryBean<?> factoryBean) {
+						try {
+							fallbackInstance = factoryBean.getObject();
+						}
+						catch (Exception e) {
+							throw new IllegalStateException(type + " create fail", e);
+						}
+						fallbackType = fallbackInstance.getClass();
+					}
 
 					if (!targetType.isAssignableFrom(fallbackType)) {
 						throw new IllegalStateException(String.format(

spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-sentinel/src/test/java/com/alibaba/cloud/sentinel/SentinelFallbackSupportFactoryBeanTests.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright 2013-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.cloud.sentinel;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.cloud.openfeign.EnableFeignClients;
+import org.springframework.cloud.openfeign.FeignAutoConfiguration;
+import org.springframework.cloud.openfeign.FeignClient;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.bind.annotation.GetMapping;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author 黄学敏（huangxuemin)
+ */
+public class SentinelFallbackSupportFactoryBeanTests {
+
+	private static final String FACTORY_BEAN_FALLBACK_MESSAGE = "factoryBean fallback message";
+
+	private static final String ORIGINAL_FALLBACK_MESSAGE = "OriginalFeign fallback message";
+
+	private final ApplicationContextRunner runner = new ApplicationContextRunner()
+			.withBean(FactoryBeanFallbackFeignFallback.class)
+			.withBean(OriginalFeignFallback.class)
+			.withConfiguration(AutoConfigurations.of(TestConfiguration.class, FeignAutoConfiguration.class))
+			.withPropertyValues("feign.sentinel.enabled=true");
+
+	@Test
+	public void shouldRunFallbackFromBeanOrFactoryBean() {
+		runner.run(ctx -> {
+			assertThat(ctx.getBean(OriginalFeign.class).get()).isEqualTo(ORIGINAL_FALLBACK_MESSAGE);
+			assertThat(ctx.getBean(FactoryBeanFallbackFeign.class).get()).isEqualTo(FACTORY_BEAN_FALLBACK_MESSAGE);
+		});
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@EnableFeignClients(clients = {OriginalFeign.class, FactoryBeanFallbackFeign.class })
+	@EnableAutoConfiguration
+	public static class TestConfiguration {
+
+	}
+
+	@FeignClient(name = "original", url = "https://original", fallback = OriginalFeignFallback.class)
+	interface OriginalFeign {
+
+		@GetMapping("/")
+		String get();
+
+	}
+
+	@FeignClient(name = "factoryBean", url = "https://factoryBean", fallback = FactoryBeanFallbackFeignFallback.class)
+	interface FactoryBeanFallbackFeign {
+
+		@GetMapping("/")
+		String get();
+
+	}
+
+	private static class FactoryBeanFallbackFeignFallback implements FactoryBean<FactoryBeanFallbackFeign> {
+
+		@Override
+		public FactoryBeanFallbackFeign getObject() {
+			return () -> FACTORY_BEAN_FALLBACK_MESSAGE;
+		}
+
+		@Override
+		public Class<?> getObjectType() {
+			return FactoryBeanFallbackFeign.class;
+		}
+
+	}
+
+	private static class OriginalFeignFallback implements OriginalFeign {
+
+		@Override
+		public String get() {
+			return ORIGINAL_FALLBACK_MESSAGE;
+		}
+
+	}
+
+}