Feign 声明式web service

Feign是一种基于HTTP的声明式、模板化的web service客户端
Spring Cloud Feign 通过@FeignClient("ribbonserver")，声明当前Interface为ribbonserver服务的客户端
通过这种方式在开发调用远程服务时可以像调用本地服务一样，通过注解的方式调用

集成Feign

创建Feign module，引入spring-cloud-starter-feign

build.gradle

apply plugin: 'org.springframework.boot'
dependencyManagement {
    imports {
        mavenBom "org.springframework.cloud:spring-cloud-dependencies:" + springCloudVersion
        mavenBom "org.springframework.boot:spring-boot-starter:"+ springBootVersion
    }
}
dependencies {
    compile ('org.springframework.cloud:spring-cloud-starter-feign')
    compile('org.springframework.cloud:spring-cloud-starter-eureka')

    compile ('org.springframework.boot:spring-boot-starter-web')
    compile('org.springframework.boot:spring-boot-starter-log4j2')
    compile ('org.springframework.boot:spring-boot-starter-thymeleaf')

    compile('org.apache.logging.log4j:log4j-1.2-api:'+ log4jAPIVersion)
    compile ('net.sourceforge.nekohtml:nekohtml:'+nekoHtmlVersion)
    testCompile ('org.springframework.boot:spring-boot-starter-test')
    testCompile group: 'junit', name: 'junit', version: '4.11'
}
configurations {
    all*.exclude module: 'spring-boot-starter-logging'
    all*.exclude module: 'logback-classic'
    all*.exclude module: 'log4j-over-slf4j'
    all*.exclude module: 'snappy-java'
}
jar {
    baseName = 'feignserver-bootcwenao'
}

配置application.yml

通过@FeignClient创建web service客户端FeignServer

@FeignClient("ribbonserver")
public interface FeignServer {
    @RequestMapping(value ="/testRealRibbon",method= RequestMethod.GET)
    String testRealRibbon(@RequestParam("content") String content);
}

创建 Controller FeignController

/**
 * @author cwenao
 * @version $Id FeignController.java, v 0.1 2017-01-15 13:50 cwenao Exp $$
 */
@Controller
public class FeignController {
    @Autowired
    FeignServer feignServer;

    @RequestMapping("/testFeign")
    @ResponseBody
    public void testFeign(String content) {
        String ribbonStr = feignServer.testRealRibbon(content);
        System.out.println(ribbonStr);
    }
}

通过 @EnableFeignClients启用FeignClient功能

/**
 * @author cwenao
 * @version $Id FeignServerApplication.java, v 0.1 2017-01-15 13:32 cwenao Exp $$
 */
@SpringBootApplication(scanBasePackages={"com.bootcwenao.feignserver"})
@EnableDiscoveryClient
@EnableFeignClients
public class FeignServerApplication {
    public static void main(String[] args) {
        new SpringApplicationBuilder(FeignServerApplication.class).web(true).run(args);
    }
}

测试调用

• ribbonserver 服务为上一节写Ribbon时的服务
• @RequestParam("content") ，在使用@RequestMapping注解时需要参数注解否则，在指定method 为POST或者GET时未使用注解的参数将被忽略
• @RequestParam("content")中"content"需要显示使用value以传递参数，不然可能会出错。
• 依次启动 服务注册中心、Ribbon Server、Feign Server

访问 Feign Server Controller http://localhost:8084/testFeign/content=Hello World

返回结果：Hello World for Spring Boot

启用Apache HTTP Client

替换默认的http client
获取http连接池等
build.gradle 引入 httpclient、feign httpclient
application.yml中启用

compile ('org.apache.httpcomponents:httpclient:'+ httpclientVersion)
    compile ('com.netflix.feign:feign-httpclient:'+ feignHttpclientVersion)

feign:
    httpclient:
        enabled:true

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代码

代码请移步 Github参考地址

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