**功能：** 通过 *Feign* 调用远程 Api 。 ## *pom.xml* 添加依赖 *feign-jackson* 和 *feign-slf4j* 。 ```xml io.github.openfeign feign-jackson ${feign.version} io.github.openfeign feign-slf4j ${feign.version} feign-core io.github.openfeign ``` ## *AresApi.java* 定义 Api 接口。 ```java import feign.Headers; import feign.Param; import feign.RequestLine; import java.util.Map; public interface AresApi { /** * 获取微信公众号 Access Token * * @param appid * @return */ @RequestLine("GET /token?appid={appid}") AresResponse getAccessToken(@Param("appid") String wAppid); } ``` ## *AresApiConfig.java* 使用 `Feign.builder()` 创建 Api 的 Bean 。 ```java import feign.Feign; import feign.jackson.JacksonDecoder; import feign.jackson.JacksonEncoder; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @Configuration public class AresApiConfig { @Bean public AresApi createAresApi(AresConfig aresConfig) { return Feign.builder() .encoder(new JacksonEncoder()) .decoder(new JacksonDecoder()) .target(AresApi.class, String.format("http://%s/", aresConfig.getDomain())); } } ``` ## *AresServiceImpl.java* 调用方法同调用普通的服务接口一样。 ```java import cn.hutool.json.JSONUtil; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service @Slf4j public class AresServiceImpl extends AbstractAresService { @Autowired private AresApi aresApi; /** * 获取微信公众号访问令牌 * * @param appId 微信公众号应用ID * @return */ @Override public AresAccessTokenData getAccessToken(String appId) { AresResponse response = aresApi.getAccessToken(appId); log.info("response : {}", JSONUtil.toJsonStr(response)); if (response != null && response.getCode() != null && response.getCode() == 200) { return response.getData(); } else { log.error("获取 Access Token 失败"); return null; } } } ```

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