OpenFeign中如何使用明文http2呢?

下文笔者讲述OpenFeign使用明文http2的方法及示例分享,如下所示

http2简介

HTTP2(超文本传输协议第2版)
   简称为h2(基于TLS/1.2或以上版本的加密连接)或h2c(非加密连接)
   是HTTP协议的的第二个主要版本,使用于万维网 
HTTP2的特点:
   1.使用静态和动态字典表来减少重复请求头的传输 
   2.使用哈夫曼编码来压缩整数和字符串
   3.服务端推送--避免多次请求

OpenFeign支持Http2的实现思路

openfeign支持Http2是基于底层的Client
    只要Client支持http2,则openFeign支持http2

openfeign可使用以下Client:
    URLConnection:
	    java9之前不支持http2
    Apache HttpClient:
	    5.0开始支持,4.X不支持
    OKHttp:
	    支持,
        h2或H2_PRIOR_KNOWLEDGE(明文http2)都支持 

下文笔者采用示例的方式讲述openFeign支持http2的示例

1.引入相应依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
        <exclusion>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <groupId>org.springframework.boot</groupId>
        </exclusion>
    </exclusions>
</dependency>
<!-- 使用undertow代替tomcat -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-undertow</artifactId>
</dependency>

注意事项:
  undertow在配置文件中
     server.http2.enabled=true无效，需采用以下代码的形式配置
 
import io.undertow.UndertowOptions;
import org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class WebConfig {
    @Bean
    public UndertowServletWebServerFactory embeddedServletContainerFactory() {
        UndertowServletWebServerFactory factory = new UndertowServletWebServerFactory();
        factory.addBuilderCustomizers(builder -> builder.setServerOption(UndertowOptions.ENABLE_HTTP2, true));
        return factory;
    }
}


2、客户端

引入openfeign及okhttp:
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-okhttp</artifactId>
</dependency>

<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>4.1.0</version>
</dependency>

application.yml中配置启用okhttp

feign:
  okhttp:
    enabled: true

由于使用明文http2
    所以需手动指定其协议
    配置如下：
 
@Bean
public okhttp3.OKHttpClient okHttpClient(){
    list<Protocol> protocols = new ArrayList<>();
    protocols.add(Protocol.H2_PRIOR_KNOWLEDGE);
    OkHttpClient.Builder builder = new okhttp3.OkHttpClient.Builder()
            .readTimeout(60, TimeUnit.SECONDS)
            .connectTimeout(60, TimeUnit.SECONDS)
            .writeTimeout(120, TimeUnit.SECONDS)
            .connectionPool(new ConnectionPool());
    // 添加拦截器用于打印响应时所使用的协议
    builder.addInterceptor(new ResponseInterceptor());
    builder.protocols(protocols);
    return builder.build();
}

拦截器打印相应的协议 
 
import okhttp3.Interceptor;
import okhttp3.Request;
import okhttp3.Response;
import org.jetbrains.annotations.NotNull;

import java.io.IOException;

public class ResponseInterceptor implements Interceptor {
    @NotNull
    @Override
    public Response intercept(@NotNull Chain chain) throws IOException {
        Request request = chain.request();
        try {
            Response response = chain.proceed(request);
            System.out.println(response.protocol());
            return response;
        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        }
    }
}

//feign接口定义如下：

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

import java.util.Map;

@FeignClient("demo3-service")
public interface Demo3Service {

    @GetMapping("/v1/demo3/demo")
    Map<String, String> demo();
}



@Autowired
private Demo3Service demo3Service;

@GetMapping("/demo3")
public Map<String, String> demo3() throws Exception {
    return demo3Service.demo();
}