Java 开源项目 OpenFeign —— feign 结合 SpringBoot

1. 前言

Spring 对 Feign 做了封装，包括常用的 encoder/decoder ，让我们能用 Bean 的形式使用 Feign。我们将沿用之前的代码。

1.1 Maven 依赖

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter</artifactId>
        </dependency>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

1.2 激活 openfeign

在 Springboot 启动类加上注解  @EnableFeignClients

2. SpringMvc 注解

与原生的 Feign 不同，在 Springboot 中要使用到 SpringMvc 的注解，这存在一些限制（比如动态改变 URL ），需要我们找 workRound 

2. 编写代码

由于使用 SpringMVC 风格，编写的代码与 feign 原生的有不少出入，需要仔细对比。

2.1 改写官方教程

我们只需要创建与 GitHub 接口相似的代码，与响应的测试代码

2.1.1 创建 Client

/**
 * @author pancc
 * @version 1.0
 */
@FeignClient(name = "gitHubs", url = " https://api.github.com", qualifier = "gitHubsClient")
public interface GitHubClient {
    @GetMapping(value = "/repos/{owner}/{repo}/contributors")
    @ResponseBody
    List<SimpleGit.Contributor> contributors(@PathVariable("owner") String owner, @PathVariable("repo") String repo);

    @Data
    @JsonIgnoreProperties(ignoreUnknown = true)
    class Contributor {
        String login;
        int contributions;
    }

}

2.1.2 创建测试代码

@SpringBootTest
class GitHubClientTest {
    @Autowired
    GitHubClient gitHubClient;

    @Test
    void contributors() {
        List<SimpleGit.Contributor> contributors = gitHubClient.contributors("OpenFeign", "feign");
        Assertions.assertNotNull(contributors);
        Assertions.assertNotEquals(0, contributors.size());

    }
}

2.1.3 动态改变请求 url

从上边的代码可以看到，我们将 url 写死在了 GitHubClient 中。让我们新增一个方法，增加 URI 类型的参数

    @GetMapping(value = "/repos/{owner}/{repo}/contributors")
    @ResponseBody
    List<SimpleGit.Contributor> contributorsWithURL(URI uri, @PathVariable("owner") String owner, @PathVariable("repo") String repo);

然后用任意字符串替换 FeignClient#url 并写一个测试：

    @Test
    void contributorsWithURL() {
        List<SimpleGit.Contributor> contributors =    gitHubClient.contributorsWithURL(URI.create("https://api.github.com"), "OpenFeign", "feign");
        Assertions.assertNotNull(contributors);
        Assertions.assertNotEquals(0, contributors.size());
    }

2.2 改写 DictFeign

2.2.1 编写 DictClient 接口

/**
 * @author pancc
 * @version 1.0
 */
@FeignClient(
        name = "dictClients",
        url = "127.0.0.1:8080",
        path = "dic",
        qualifier = "dictClients"
)
public interface DictClient {
    /**
     * @see FeignController#details
     */
    @GetMapping("details")
    Dict details();

    /**
     * @see FeignController#details
     */
    @GetMapping("details")
    Dict detailsWithURI(URI uri);


    /**
     * @see FeignController#startsWith
     */
    @GetMapping("startsWith/{query}")
    List<String> startsWith(@PathVariable("query") String query);


    /**
     * @see FeignController#updateFirst
     */
    @PutMapping("updateFirst?target={target}")
    List<String> updateFirst(@PathVariable("target") String target);

    /**
     * @see FeignController#headers
     */
    @GetMapping("headers")
    Map<String, Object> headers(@RequestHeader Map<String, Object> headers);

    /**
     * @see FeignController#startAndEnd
     */
    @GetMapping("query")
    List<String> startAndEnd(@RequestParam Map<String, String> map);

    /**
     * @see FeignController#replace
     */
    @PutMapping(value = "replace", consumes = MediaType.APPLICATION_JSON_VALUE)
    List<String> replace(Map<String, String> map);


    /**
     * @see FeignController#add
     */
    @PostMapping(value = "add", consumes = MediaType.APPLICATION_JSON_VALUE)
    List<String> add(Map<String, Object> map);

    /**
     * @see FeignController#deleteFirst
     */
    @DeleteMapping("deleteFirst")
    List<String> deleteFirst();
}

2.2.2 编写对应的测试方法

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
class DictClientTest {
    private final Dict dict = Dict.Instance;
    @Autowired
    private DictClient dictClient;


    @Test
    void details() {
        Assertions.assertEquals(dict, dictClient.details());
    }

    @Test
    void startsWith() {
        Assertions.assertEquals(3, dictClient.startsWith("a").size());
    }


    @Test
    void startAndEnd() {
        Map<String, String> map = Maps.newHashMap();
        map.put("startsWith", "e");
        map.put("endsWith", "e");
        Assertions.assertEquals(1, dictClient.startAndEnd(map).size());
    }

    @Test
    void replace() {
        Assertions.assertNotEquals(dictClient.replace(Collections.singletonMap("bike", "bikes")).indexOf("bikes"), -1);
    }

    @Test
    void updateFirst() {
        Assertions.assertEquals("game", dictClient.updateFirst("game").get(0));
    }

    @Test
    void deleteFirst() {
        Assertions.assertEquals(13, dictClient.deleteFirst().size());
    }


    @Test
    void headers() {
        Map<String, Object> headers = Maps.newHashMap();
        headers.put("age", 15);
        headers.put("length", 21);
        Assertions.assertTrue(dictClient.headers(headers).containsKey("age"));
        Assertions.assertTrue(dictClient.headers(headers).containsKey("length"));
    }

    @Test
    void add() {
        String var1 = "go~";
        String var2 = "back";
        List<String> adds = dictClient.add(Maps.toMap(Arrays.asList(var1, var2), input -> input));
        Assertions.assertTrue(adds.contains(var1));
        Assertions.assertTrue(adds.contains(var2));

    }
}

2.3 改写登录流程

2.3.1 配置 FormEncoder

由于使用 Spring 默认使用 Jackson（Json） ，我们需要手动配置一个 FormEncoder，需要注意的是配置类不能写成 Component 以避免自动配置的 encoder 被替换；

/**
 * @author pancc
 * @version 1.0
 */
public class LoginClientConfig {
    @Bean
    public FormEncoder formEncoder() {
        return new FormEncoder(new JacksonEncoder());
    }
}

2.3.2 编写 LoginClient

/**
 * @author pancc
 * @version 1.0
 */
@FeignClient(name = "loginClient", url = "127.0.0.1:8080", configuration = LoginClientConfig.class)
public interface LoginClient {
    /**
     * @see LoginController#loginWithJson
     */
    @PostMapping(value = "login", consumes = MediaType.APPLICATION_JSON_VALUE)
    Response loginWithJson(@RequestBody UserInfo userInfo);

    /**
     * @see LoginController#loginWithForm
     */
    @PostMapping(value = "login", consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
    Response loginWithForm(UserInfo userInfo);


    /**
     * @see LoginController#loginWithToken
     */
    @PostMapping("login")
    Response loginWithToken(@RequestHeader("Authorization") String token);


}

2.3.3 编写测试

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
class LoginClientTest {

    @Autowired
    private LoginClient loginClient;

    @Test
    void loginWithJson() {
        Response res = loginClient.loginWithJson(new UserInfo().setPassword("root").setUsername("admin"));
        Assertions.assertEquals(200, res.getStatus());
    }

    @Test
    void loginWithForm() {
        Response res = loginClient.loginWithForm(new UserInfo().setPassword("root").setUsername("admin"));
        Assertions.assertEquals(200, res.getStatus());
    }

    @Test
    void loginWithToken() {
        Response res = loginClient.loginWithToken("Bearer user-token");
        Assertions.assertEquals(200, res.getStatus());
    }

}

3. 代理

代理的使用总是不可避免地，就像怕配置 encoder 一样，让我们为 GitHubClient 配置一个代理

3.1 代理配置类

参照 feign 的基本使用与 2.3.1，我们可以很快的写配置类，同样避免将配置类写成 Component

/**
 * @author pancc
 * @version 1.0
 */
public class GitHubClientConfig {
    @Bean
    public Client client() {
        okhttp3.OkHttpClient okHttpClient =
                new okhttp3.OkHttpClient.Builder().proxy(new Proxy(Proxy.Type.SOCKS, new InetSocketAddress("127.0.0.1", 10808))).build();
        return new OkHttpClient(okHttpClient);
    }
}

3.2 修改 GithubClient 配置

@FeignClient(name = "gitHubs", url = "https://api.github.com", qualifier = "gitHubsClient", configuration = GitHubClientConfig.class)
public interface GitHubClient {
....

4. 总结要点

4.1 依赖

     <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter</artifactId>
        </dependency>
 <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

4.2 编写方式

1. 启动注解 @EnableFeignClients
2. feign 接口使用 @FeignClient 注解
3. feign 接口使用 SpringMVC 风格
4. feign 的配置写在一个不被 Spring 实例化的配置类中，各种 feign 基本模块写成 Bean。启用时只添加配置类进相应的 feign 接口的注解字段中
5. 使表单需要配置 FormEncoder
6. feign 接口方法的第一个参数可以为 URI ，用于动态替换 FeignClient 中的 url