@RequestLine("POST /postJson")
    @Headers("Content-Type: application/json")
    OrderDto postJson (OrderDto dto);
    @RequestLine("POST /postForm")
    @Headers("Content-Type: application/x-www-form-urlencoded")
    OrderDto postForm (@Param("id") String id, @Param("name") String name);
    @RequestLine("GET /get?id={id}&name={name}")
    String get(@Param("id") String id, @Param("name") String name);
    @RequestLine("GET /get")
    String getByMap(@QueryMap Map<String, Object> param);
    @RequestLine("GET /getById/{id}")
    String getById(@Param("id") String id);

<dependency>
   <groupId>io.github.openfeign</groupId>
   <artifactId>feign-core</artifactId>
   <version>11.6</version>
</dependency>
<dependency>
   <groupId>io.github.openfeign</groupId>
   <artifactId>feign-spring4</artifactId>
   <version>11.6</version>
</dependency>
<dependency>
   <groupId>io.github.openfeign</groupId>
   <artifactId>feign-jackson</artifactId>
   <version>11.6</version>
</dependency>
<dependency>
   <groupId>io.github.openfeign</groupId>
   <artifactId>feign-httpclient</artifactId>
   <version>11.6</version>
</dependency>
<dependency>
   <groupId>io.github.openfeign.form</groupId>
   <artifactId>feign-form</artifactId>
   <version>3.8.0</version>
</dependency>

public interface HelloFacade {
    // spring注解用法
    @PostMapping(value = "/postJson", consumes = "application/json")
    OrderDto postJson (@RequestBody OrderDto dto);
    @PostMapping(value = "/postForm", consumes = "application/x-www-form-urlencoded")
    OrderDto postForm (OrderDto dto);
    @GetMapping("/get")
    OrderDto get(@RequestParam("id") Long id, @RequestParam("name") String name);
    @GetMapping("/getByMap")
    OrderDto getByMap(@RequestParam("param") Map<String, Object> param);
    @GetMapping("/getById/{id}")
    OrderDto getById(@PathVariable("id") Long id);
}

public class MyJacksonDecoder extends JacksonDecoder {
    @Override
    public Object decode(Response response, Type type) throws IOException {
        if (response.body() == null) {
            return null;
        }
        if (type == String.class) {
            return StreamUtils.copyToString(response.body().asInputStream(), StandardCharsets.UTF_8);
        }
        return super.decode(response, type);
    }
}

    public static CloseableHttpClient getHttpClient() throws KeyStoreException,
            NoSuchAlgorithmException, KeyManagementException {
        SSLContextBuilder builder = new SSLContextBuilder();
        builder.loadTrustMaterial(null, new TrustSelfSignedStrategy());
        SSLConnectionSocketFactory sslSf = new SSLConnectionSocketFactory(builder.build());
        // 配置同時(shí)支持 HTTP 和 HTTPS
        Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", PlainConnectionSocketFactory.getSocketFactory())
                .register("https", sslSf).build();
        // 初始化連接管理器
        PoolingHttpClientConnectionManager poolConnManager =
                new PoolingHttpClientConnectionManager(socketFactoryRegistry);
        // 同時(shí)最多連接數(shù)（不設(shè)置默認(rèn)20）
        poolConnManager.setMaxTotal(20);
        // 設(shè)置最大路由（不設(shè)置默認(rèn)2）
        poolConnManager.setDefaultMaxPerRoute(10);
        // 此處解釋下MaxtTotal和DefaultMaxPerRoute的區(qū)別：
        // 1、MaxtTotal是整個(gè)池子的大??；
        // 2、DefaultMaxPerRoute是根據(jù)連接到的主機(jī)對MaxTotal的一個(gè)細(xì)分；比如：
        // MaxtTotal=400 DefaultMaxPerRoute=200
        // 而只連接到http://www.abc.com時(shí)，到這個(gè)主機(jī)的并發(fā)最多只有200；而不是400；
        // 連接到http://www.bac.com 和 http://www.ccd.com時(shí)，到每個(gè)主機(jī)的并發(fā)最多只有200；即加起來是400（但不能超過400）；
        // 所以起作用的設(shè)置是DefaultMaxPerRoute
        // 初始化httpClient
        RequestConfig config = RequestConfig.custom().setConnectTimeout(1000)
                .setConnectionRequestTimeout(2000)
                .setSocketTimeout(10000).build();
        return HttpClients.custom()
                // 設(shè)置連接池管理
                .setConnectionManager(poolConnManager)
                .setDefaultRequestConfig(config)
                //  過期連接關(guān)閉
                .evictIdleConnections(60, TimeUnit.SECONDS)
                .setConnectionTimeToLive(600, TimeUnit.SECONDS)
                // 設(shè)置重試次數(shù)
                .setRetryHandler(new DefaultHttpRequestRetryHandler(1, false)).build();
    }

    public static void main(String[] args) throws Exception{
        HelloFacade target = Feign.builder()
                // spring注解
                .contract(new SpringContract())
                .encoder(new FormEncoder(new JacksonEncoder()))
                .decoder(new MyJacksonDecoder())
                .client(new ApacheHttpClient(getHttpClient()))
                .logLevel(Logger.Level.BASIC)
                .target(HelloFacade.class, "http://localhost:8080");
        String result = target.testStr("hello world");
        System.out.println(result);
    }

@Component
public class TargetUrlRequestInterceptor implements RequestInterceptor {
    @Value("${feign.target.url:http://localhost:7777}")
    private String targetUrl;
    @Override
    public void apply(RequestTemplate template) {
        // 可以添加自定義header
        template.header("customHeader", "123");
        // 可以改變初始化時(shí)的目標(biāo)地址
        template.target(targetUrl);
    }
}