Spring Boot 2关于http接口调用(5)

使用FeignClient

Feign是一个声明式的Web服务客户端，使用Feign可使得Web服务客户端的写入更加方便。只需要几个注解就可以实现基本的http调用功能，减少了许多重复的代码。这里只介绍其单独使用的场景，跟微服务其他组件的使用不做介绍。

包引用

不同版本需要引入的包不一样，这里spring boot 2引入的是
compile group: ‘org.springframework.cloud’, name: ‘spring-cloud-starter-openfeign’, version: ‘2.0.2.RELEASE’

启用FeignClient

这里需要在入口类使用注解EnableFeignClients

@EnableFeignClients(basePackages = {"org.ghost.springboot2.demo.test.service"})
public class Application { 
}

配置文件修改

feign:
  httpclient:
    enabled: false
  okhttp:
    enabled: false
  compression:
    request:
      enabled: true
      mime-types: text/xml,application/xml,application/json
      min-request-size: 2048
    response:
      enabled: true
  hystrix:
    enabled: false

定义接口使用注解

@FeignClient(name = "helloApi", url = "http://localhost:9999")
public interface ITestHelloService {
    @RequestMapping(value = "demo/hello", method = RequestMethod.GET)
    HttpRspDTO getTestHello(@RequestParam(value = " msg") String msg);
    
    @RequestMapping(value = "demo/hello", method = RequestMethod.POST)
    HttpRspDTO postTestHello(@RequestBody Map reqBody);
}

其他的RequestMapping等注解都是Spring中的注解。

针对FeignClient里面有很多参数，可以灵活运用

url参数

这里可以写死具体的地址，也可以是动态参数，例如：${serviceClient.config.helloServiceApiPath}
${serviceClient.config.helloServiceApiPath}可以application.yml里面配置的参数

configuration参数

这个参数可以配置一些编解码、拦截、日志等信息，可以继承FeignClientsConfiguration

public class HelloServiceApiConfig extends FeignClientsConfiguration {
    @Override
    public Feign.Builder feignBuilder(Retryer retryer) {
        Feign.Builder builder = super.feignBuilder(retryer);
        builder.requestInterceptor(new CommonInterceptor());
        return builder;
    }

    @Override
    public Decoder feignDecoder() {
        return new JacksonDecoder(JacksonUtil.useDefaultMapper().getMapper());
    }

    @Override
    public Encoder feignEncoder() {
        return new JacksonEncoder(JacksonUtil.nonEmptyMapper().getMapper());
    }

    @Bean
    Logger.Level feignLogLevel() {
        return Logger.Level.FULL;
    }
}
// 自定义拦截器
public class CommonInterceptor implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate template) {
        Map> headerMap = template.headers();
        if (MapUtils.isNotEmpty(headerMap) && CollectionUtils.isNotEmpty(headerMap.get("Content-Type"))) {
            //
        } else {
            template.header("Content-Type", "application/json; charset=utf-8");
        }
        template.header("uuid", UUID.randomUUID().toString());
    }
}

单元测试

在入口类使用了EnableFeignClients注解，那么使用了FeignClient注解的接口会自动生成bean。在使用的时候只需要自动注入就可以了。

@RunWith(SpringRunner.class)
@SpringBootTest(classes = Application.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class, DataSourceTransactionManagerAutoConfiguration.class, HibernateJpaAutoConfiguration.class})
@EnableFeignClients(basePackages = {"org.ghost.springboot2.demo.test.service"})
public class FeignTest {
    @Autowired
    private ITestHelloService testHelloService;

    @Test
    public void test1() {
        long begin = System.currentTimeMillis();

        HttpRspDTO rspDTO = testHelloService.getTestHello("这是一条测试数据");

        long end = System.currentTimeMillis();
        System.out.println("*****消耗时间(秒):" + (end - begin) / 1000.0);
        System.out.println(rspDTO);
    }

    @Test
    public void test2() {
        long begin = System.currentTimeMillis();

        Map paraMap = new HashMap();
        paraMap.put("msg", "这是一条测试数据");
        HttpRspDTO rspDTO = testHelloService.postTestHello(paraMap);

        long end = System.currentTimeMillis();
        System.out.println("*****消耗时间(秒):" + (end - begin) / 1000.0);
        System.out.println(rspDTO);
    }
}

源码位置

https://gitee.com/ceclar123/spring-boot-demo/tree/master/ch01