集成Feign简化调用方式

changelog.md

@@ -475,16 +475,16 @@ spring:
 Port of the service provider: 19922
 ```
 
-
 # [集成ribbon实现客户端负载均衡](#集成ribbon实现客户端负载均衡)
 > 代码分支: load-balancer
 
 ## 关于ribbon
-> (翻译自官方文档)ribbon是一个提供如下功能的依赖包:
-> - 负载均衡
-> - 容错机制
-> - 支持多种协议(HTTP, TCP, UDP)，支持异步和响应式的调用方式
-> - 缓存和批处理
+
+(翻译自官方文档)ribbon是一个提供如下功能的依赖包:
+- 负载均衡
+- 容错机制
+- 支持多种协议(HTTP, TCP, UDP)，支持异步和响应式的调用方式
+- 缓存和批处理
 
 #### ribbon核心API
 
@@ -971,6 +971,74 @@ public class ConsumerApplication {
 
 访问```http://localhost:8080/foo```
 
+# [集成Feign简化调用方式](#集成Feign简化调用方式)
+> 代码分支: open-feign
+
+## 关于feign
+[Open Feign](https://github.com/OpenFeign/feign) 是一个简化http调用方式的Java客户端，通过处理接口的注解生成响应报文。使用示例:
+
+```java
+interface HelloService {
+
+  @RequestLine("GET /hello")
+  String hello();
+}
+
+@Test
+public void testOpenFeign() {
+  HelloService helloService = Feign.builder()
+          .target(HelloService.class, "http://localhost:8080");
+  String response = helloService.hello();
+}
+```
+
+Spring Cloud基于Open Feign开发了[Spring Cloud OpenFeign](https://github.com/spring-cloud/spring-cloud-openfeign) ，得以支持Spring Mvc的注解（通过实现feign的Contract接口，实现类为SpringMvcContract），使用示例:
+
+```java
+interface WorldService {
+
+    @GetMapping("/world")
+    String world();
+}
+
+@Test
+public void testSpringCloudOpenFeign() {
+    WorldService worldService = Feign.builder()
+            .contract(new SpringMvcContract())
+            .target(WorldService.class, "http://localhost:8080");
+    String response = worldService.world();
+}
+```
+
+可以dubug上面两个示例，代码放在测试类FeignTest中，重点关注Contract接口对注解的解析
+
+
+#### Open Feign核心API
+
+Open Feign工作流程:
+
+![](./assets/feign工作流程.png)
+
+一、Contract接口
+
+负责解析Feign客户端接口的类注解、方法注解和参数。实现类```feign.Contract.Default```支持Open Feign的注解，比如上面第一个示例中的RequestLine注解；Spring Cloud OpenFeign开发的实现类```SpringMvcContract```支持Spring MVC的注解，如GetMapping、PostMapping、RequestMapping。
+
+二、Encoder接口
+
+编码器，将请求对象编码为请求体
+
+三、Decoder接口
+
+解码器，将响应体解码为对象
+
+四、RequestInterceptor拦截器接口
+
+对请求进行拦截处理
+
+五、Client接口
+
+提交http请求的接口
+
 
 
 

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

@@ -1,8 +1,5 @@
 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;
@@ -13,7 +10,6 @@ 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
@@ -32,81 +28,23 @@ public class LoadBalancerFeignClient implements Client {
         this.delegate = delegate;
     }
 
+    @SuppressWarnings("deprecation")
     @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<>(),
+        try {
+            //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);
+
+            Request newRequest = Request.create(request.httpMethod(), uri.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;
+            return delegate.execute(newRequest, options);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
         }
     }
 }