Source/BladeX-Tool/blade-core-cloud/src/main/java/org/springblade/core/cloud/sentinel/BladeFeignSentinel.java

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/*
 * Copyright 2013-2018 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 org.springblade.core.cloud.sentinel;

import com.alibaba.cloud.sentinel.feign.SentinelContractHolder;
import feign.Contract;
import feign.Feign;
import feign.InvocationHandlerFactory;
import feign.Target;
import org.springframework.cloud.openfeign.FallbackFactory;
import lombok.SneakyThrows;
import org.springblade.core.cloud.feign.BladeFallbackFactory;
import org.springframework.beans.BeansException;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.cloud.openfeign.FeignContext;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.StringUtils;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.util.Map;

/**
 * feign集成sentinel自动配置
 * é‡å†™ {@link com.alibaba.cloud.sentinel.feign.SentinelFeign} é€‚配最新API
 *
 * @author Chill
 */
public class BladeFeignSentinel {

   public static Builder builder() {
      return new Builder();
   }

   public static final class Builder extends Feign.Builder implements ApplicationContextAware {
      private Contract contract = new Contract.Default();
      private ApplicationContext applicationContext;
      private FeignContext feignContext;

      @Override
      public Feign.Builder invocationHandlerFactory(
         InvocationHandlerFactory invocationHandlerFactory) {
         throw new UnsupportedOperationException();
      }

      @Override
      public Builder contract(Contract contract) {
         this.contract = contract;
         return this;
      }

      @Override
      public Feign build() {
         super.invocationHandlerFactory(new InvocationHandlerFactory() {
            @SneakyThrows
            @Override
            public InvocationHandler create(Target target, Map<Method, MethodHandler> dispatch) {
               // æ³¨è§£å–值以避免循环依赖的问题
               FeignClient feignClient = AnnotationUtils.findAnnotation(target.type(), FeignClient.class);
               Class fallback = feignClient.fallback();
               Class fallbackFactory = feignClient.fallbackFactory();
               String contextId = feignClient.contextId();

               if (!StringUtils.hasText(contextId)) {
                  contextId = feignClient.name();
               }

               Object fallbackInstance;
               FallbackFactory fallbackFactoryInstance;
               // åˆ¤æ–­fallback类型
               if (void.class != fallback) {
                  fallbackInstance = getFromContext(contextId, "fallback", fallback, target.type());
                  return new BladeSentinelInvocationHandler(target, dispatch, new FallbackFactory.Default(fallbackInstance));
               }
               if (void.class != fallbackFactory) {
                  fallbackFactoryInstance = (FallbackFactory) getFromContext(contextId, "fallbackFactory", fallbackFactory, FallbackFactory.class);
                  return new BladeSentinelInvocationHandler(target, dispatch, fallbackFactoryInstance);
               }
               // é»˜è®¤fallbackFactory
               BladeFallbackFactory bladeFallbackFactory = new BladeFallbackFactory(target);
               return new BladeSentinelInvocationHandler(target, dispatch, bladeFallbackFactory);
            }

            private Object getFromContext(String name, String type, Class fallbackType, Class targetType) {
               Object fallbackInstance = feignContext.getInstance(name, fallbackType);
               if (fallbackInstance == null) {
                  throw new IllegalStateException(
                     String.format("No %s instance of type %s found for feign client %s",
                        type, fallbackType, name)
                  );
               }

               if (!targetType.isAssignableFrom(fallbackType)) {
                  throw new IllegalStateException(
                     String.format("Incompatible %s instance. Fallback/fallbackFactory of type %s is not assignable to %s for feign client %s",
                        type, fallbackType, targetType, name)
                  );
               }
               return fallbackInstance;
            }
         });
         super.contract(new SentinelContractHolder(contract));
         return super.build();
      }

      @Override
      public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
         this.applicationContext = applicationContext;
         feignContext = this.applicationContext.getBean(FeignContext.class);
      }
   }

}