spring-cloud-starter-feign 组件在spring boot中的应用：访问Oauth2资源服务器的资源接口

spring-cloud-starter-feign 组件在spring boot中的应用：

访问Oauth2资源服务器的资源接口

   

      如果对https://github.com/OpenFeign/feign  不了解的，可以去官网浏览一下。由于spring对其扩展，我们可以利用spring的注解及spring boot 的特性来使用该组件，可参考文档：http://cloud.spring.io/spring-cloud-static/Dalston.SR1/#spring-cloud-feign 。

    下面的例子是spring boot项目中，访问Oauth2资源服务器的资源接口（非集群环境下）。

    maven pom文件需要引入对spring cloud相关依赖：

 <dependencyManagement>        <dependencies>            <dependency>                <groupId>org.springframework.boot</groupId>                <artifactId>spring-boot-dependencies</artifactId>                <version>${spring-boot.version}</version>                <type>pom</type>                <scope>import</scope>            </dependency>            <dependency>                <groupId>org.springframework.cloud</groupId>                <artifactId>spring-cloud-dependencies</artifactId>                <version>Dalston.SR1</version>                <type>pom</type>                <scope>import</scope>            </dependency>        </dependencies>    </dependencyManagement>

 为了使用feign组件，我们增加依赖：

<dependency>            <groupId>org.springframework.cloud</groupId>            <artifactId>spring-cloud-starter-config</artifactId>            <exclusions>                <!--配置中心去掉，会自动连接 -->                <exclusion>                    <groupId>org.springframework.cloud</groupId>                    <artifactId>spring-cloud-config-client</artifactId>                </exclusion>            </exclusions>        </dependency>        <dependency>            <groupId>org.springframework.cloud</groupId>            <artifactId>spring-cloud-starter-feign</artifactId>        </dependency>        <dependency>            <groupId>com.netflix.feign</groupId>            <artifactId>feign-okhttp</artifactId>            <version>8.18.0</version>        </dependency>

     为了使用spring boot 的自动配置，我们需要引入       @EnableFeignClients 注解，自动扫描Feign相关代码。

@SpringBootApplication(        exclude = {DataSourceAutoConfiguration.class,                MybatisAutoConfiguration.class,                JpaRepositoriesAutoConfiguration.class,                HibernateJpaAutoConfiguration.class},        scanBasePackages = {"com.sdcuike.practice",                "com.sdcuike.spring.controller.advice"})@EnableFeignClients@Slf4jpublic class Application {    public static void main(String[] args) throws UnknownHostException {        SpringBootApplicationUtil.runSpringBootApplication(log, args, Application.class);    }    }

 为了访问资源服务器上的资源，我们定义demo接口：

/** * Created by beaver on 2017/5/27.<br> * <p> * {@link https://jmnarloch.wordpress.com/2015/10/14/spring-cloud-feign-oauth2-authentication  } */@FeignClient(name = "exampleService",        url = "${exampleService.ribbon.listOfServers}",        configuration = {OAuth2FeignAutoConfiguration.class})@RequestMapping(value = "/springBoot/example"        , consumes = MediaType.APPLICATION_JSON_UTF8_VALUE        , produces = MediaType.APPLICATION_JSON_UTF8_VALUE)public interface ExampleServiceFeignClient {    @GetMapping("/")    ModelResult<String> home();}

  由于spring-cloud-feign对feign做了扩展，所以，我们可以使用spring的web相关注解，来使用feign，大大方便了我们的spring 应用。其关键的配置在于：

@FeignClient(name = "exampleService",        url = "${exampleService.ribbon.listOfServers}",        configuration = {OAuth2FeignAutoConfiguration.class})

  注解中name属性最新版本必须要求有，而url的出现，主要显示的配置feign访问的服务地址。

  OAuth2FeignAutoConfiguration类主要是feign组件利用Oauth2的认证token来访问资源服务器上的资源。

/** * Created by beaver on 2017/6/3. */@Configurationpublic class OAuth2FeignAutoConfiguration {        @Bean    public RequestInterceptor oauth2FeignRequestInterceptor(@Qualifier("practiceOAuth2RestTemplate") OAuth2RestTemplate oAuth2RestTemplate) {        return new OAuth2FeignRequestInterceptor(oAuth2RestTemplate);    }}

/** * Created by beaver on 2017/6/3. */public class OAuth2FeignRequestInterceptor implements RequestInterceptor {        private final Logger LOGGER = LoggerFactory.getLogger(getClass());        private static final String AUTHORIZATION_HEADER = "Authorization";        private static final String BEARER_TOKEN_TYPE = "Bearer";        private final OAuth2RestTemplate oAuth2RestTemplate;            public OAuth2FeignRequestInterceptor(OAuth2RestTemplate oAuth2RestTemplate) {        Assert.notNull(oAuth2RestTemplate, "Context can not be null");        this.oAuth2RestTemplate = oAuth2RestTemplate;    }        @Override    public void apply(RequestTemplate template) {        LOGGER.debug("Constructing Header {} for Token {}", AUTHORIZATION_HEADER, BEARER_TOKEN_TYPE);        template.header(AUTHORIZATION_HEADER,                String.format("%s %s",                        BEARER_TOKEN_TYPE,                        oAuth2RestTemplate.getAccessToken().toString()));            }}

  其主要思路是利用feign的的扩展RequestInterceptor，对于每次请求我们自动设置Oauth2的AccessToken 头信息。

  对于Oauth2ClientConfig 的配置在此不再复述，具体请看代码：

https://github.com/sdcuike/spring-boot-oauth2-demo/tree/blog-2017-07-16/spring-boot-oauth-resource-server/src/main/java/com/sdcuike/practice