集成Feign简化调用方式

mini-spring-cloud-openfeign/pom.xml

@@ -60,6 +60,11 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
+
+        <dependency>
+            <groupId>cn.hutool</groupId>
+            <artifactId>hutool-all</artifactId>
+        </dependency>
     </dependencies>
 
 </project>

mini-spring-cloud-openfeign/src/main/java/com/github/cloud/openfeign/FeignAutoConfiguration.java

@@ -0,0 +1,17 @@
+package com.github.cloud.openfeign;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * @author derek(易仁川)
+ * @date 2022/4/9
+ */
+@Configuration
+public class FeignAutoConfiguration {
+
+    @Bean
+    public FeignContext feignContext() {
+        return new FeignContext();
+    }
+}

mini-spring-cloud-openfeign/src/main/java/com/github/cloud/openfeign/FeignClientFactoryBean.java

@@ -1,7 +1,11 @@
 package com.github.cloud.openfeign;
 
-import com.github.cloud.openfeign.support.SpringMvcContract;
+import feign.Client;
+import feign.Contract;
 import feign.Feign;
+import feign.Target.HardCodedTarget;
+import feign.codec.Decoder;
+import feign.codec.Encoder;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.context.ApplicationContext;
@@ -23,9 +27,18 @@ public class FeignClientFactoryBean implements FactoryBean<Object>, ApplicationC
 
     @Override
     public Object getObject() throws Exception {
+        FeignContext feignContext = applicationContext.getBean(FeignContext.class);
+        Encoder encoder = feignContext.getInstance(contextId, Encoder.class);
+        Decoder decoder = feignContext.getInstance(contextId, Decoder.class);
+        Contract contract = feignContext.getInstance(contextId, Contract.class);
+        Client client = feignContext.getInstance(contextId, Client.class);
+
         return Feign.builder()
-                .contract(new SpringMvcContract())
-                .target(type, "http://localhost:1234");
+                .encoder(encoder)
+                .decoder(decoder)
+                .contract(contract)
+                .client(client)
+                .target(new HardCodedTarget<>(type, contextId, "http://" + contextId));
     }
 
     @Override

mini-spring-cloud-openfeign/src/main/java/com/github/cloud/openfeign/FeignClientSpecification.java

@@ -0,0 +1,55 @@
+package com.github.cloud.openfeign;
+
+import org.springframework.cloud.context.named.NamedContextFactory;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+/**
+ * @author derek(易仁川)
+ * @date 2022/4/9
+ */
+public class FeignClientSpecification implements NamedContextFactory.Specification {
+
+    private String name;
+
+    private Class<?>[] configuration;
+
+    public FeignClientSpecification(String name, Class<?>[] configuration) {
+        this.name = name;
+        this.configuration = configuration;
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public Class<?>[] getConfiguration() {
+        return configuration;
+    }
+
+    public void setConfiguration(Class<?>[] configuration) {
+        this.configuration = configuration;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        FeignClientSpecification that = (FeignClientSpecification) o;
+        return name.equals(that.name) && Arrays.equals(configuration, that.configuration);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = Objects.hash(name);
+        result = 31 * result + Arrays.hashCode(configuration);
+        return result;
+    }
+}

mini-spring-cloud-openfeign/src/main/java/com/github/cloud/openfeign/FeignClientsConfiguration.java

@@ -0,0 +1,46 @@
+package com.github.cloud.openfeign;
+
+import com.github.cloud.openfeign.ribbon.LoadBalancerFeignClient;
+import com.github.cloud.openfeign.support.SpringMvcContract;
+import feign.Client;
+import feign.Contract;
+import feign.codec.Decoder;
+import feign.codec.Encoder;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * 配置feign的核心API
+ *
+ * @author derek(易仁川)
+ * @date 2022/4/9
+ */
+@Configuration
+public class FeignClientsConfiguration {
+
+    @Bean
+    @ConditionalOnMissingBean
+    public Encoder encoder() {
+        return new Encoder.Default();
+    }
+
+    @Bean
+    @ConditionalOnMissingBean
+    public Decoder decoder() {
+        return new Decoder.Default();
+    }
+
+    @Bean
+    @ConditionalOnMissingBean
+    public Contract contract() {
+        return new SpringMvcContract();
+    }
+
+    @Bean
+    @ConditionalOnMissingBean
+    public Client client(LoadBalancerClient loadBalancerClient) {
+        return new LoadBalancerFeignClient(loadBalancerClient, new Client.Default(null, null));
+    }
+}

mini-spring-cloud-openfeign/src/main/java/com/github/cloud/openfeign/FeignContext.java

@@ -0,0 +1,16 @@
+package com.github.cloud.openfeign;
+
+import org.springframework.cloud.context.named.NamedContextFactory;
+
+/**
+ * 为每个feign客户端创建一个应用上下文(ApplicationContext)，隔离每个feign客户端的配置
+ *
+ * @author derek(易仁川)
+ * @date 2022/4/9
+ */
+public class FeignContext extends NamedContextFactory<FeignClientSpecification> {
+
+    public FeignContext() {
+        super(FeignClientsConfiguration.class, "feign", "feign.client.name");
+    }
+}

mini-spring-cloud-openfeign/src/main/java/com/github/cloud/openfeign/ribbon/LoadBalancerFeignClient.java

@@ -0,0 +1,112 @@
+package com.github.cloud.openfeign.ribbon;
+
+import com.netflix.client.ClientException;
+import com.netflix.client.ClientRequest;
+import com.netflix.client.IResponse;
+import feign.Client;
+import feign.Request;
+import feign.Response;
+import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
+
+import java.io.IOException;
+import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * 具备负载均衡能力的feign client
+ *
+ * @author derek(易仁川)
+ * @date 2022/4/9
+ */
+public class LoadBalancerFeignClient implements Client {
+
+    private LoadBalancerClient loadBalancerClient;
+
+    private Client delegate;
+
+    public LoadBalancerFeignClient(LoadBalancerClient loadBalancerClient, Client delegate) {
+        this.loadBalancerClient = loadBalancerClient;
+        this.delegate = delegate;
+    }
+
+    @Override
+    public Response execute(Request request, Request.Options options) throws IOException {
+        //客户端负载均衡
+        URI original = URI.create(request.url());
+        String serviceId = original.getHost();
+        //选择服务实例
+        ServiceInstance serviceInstance = loadBalancerClient.choose(serviceId);
+        //重建请求URI
+        URI uri = loadBalancerClient.reconstructURI(serviceInstance, original);
+
+        Response response = delegate.execute(new RibbonRequest(request, uri).toRequest(), options);
+        return new RibbonResponse(uri, response).getResponse();
+    }
+
+    private static class RibbonRequest extends ClientRequest {
+
+        private Request request;
+
+        public RibbonRequest(Request request, URI uri) {
+            this.request = request;
+            setUri(uri);
+        }
+
+        @SuppressWarnings("deprecation")
+        private Request toRequest() {
+            return Request.create(request.httpMethod(), getUri().toASCIIString(), new HashMap<>(),
+                    request.body(), StandardCharsets.UTF_8);
+        }
+    }
+
+    private static class RibbonResponse implements IResponse {
+
+        private final URI uri;
+
+        private final Response response;
+
+        protected RibbonResponse(URI uri, Response response) {
+            this.uri = uri;
+            this.response = response;
+        }
+
+        @Override
+        public Object getPayload() throws ClientException {
+            return response.body();
+        }
+
+        @Override
+        public boolean hasPayload() {
+            return response.body() != null;
+        }
+
+        @Override
+        public boolean isSuccess() {
+            return response.status() == 200;
+        }
+
+        @Override
+        public URI getRequestedURI() {
+            return uri;
+        }
+
+        @Override
+        public Map<String, ?> getHeaders() {
+            return new HashMap<>();
+        }
+
+        @Override
+        public void close() throws IOException {
+            if (response != null && response.body() != null) {
+                response.body().close();
+            }
+        }
+
+        public Response getResponse() {
+            return response;
+        }
+    }
+}

mini-spring-cloud-openfeign/src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
+  com.github.cloud.openfeign.FeignAutoConfiguration