SpringBoot动态Feign服务调用详解

@RestController
public class OrderController {
    // 模拟数据库存储数据
    private static Map<String, Object> maps = new HashMap<>(10);
    static {
        maps.put("1", "笔记本");
    }
    @GetMapping(value = "/getOrderById/{oId}")
    public Object getOrderById(@PathVariable(name = "oId") String oid) {
        return maps.get(oid);
    }
    @PostMapping(value = "/addOrder")
    public boolean addOrder(@RequestBody Map<String, String> orderMap) {
        try {
            maps.putAll(orderMap);
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
}

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

/**
 * Description: 通用接口,里面定义通用方法
 *  注意: 由于服务生产者所有的接口的返回值都是json格式的字符串,
 *         所以这里的通用接口的返回值最好使用String类型!!!
 */
public interface DynamicService {
    /**
     * post方法对应的方法
     * @param url 服务生产者Handler方法请求映射地址
     * @param params 服务生产者Handler方法参数
     * @return
     */
    @PostMapping(value = "{url}")
    String executePostRequest(@PathVariable("url") String url, @RequestBody Object params);
    @GetMapping(value = "{url}")
    String executeGetRequest(@PathVariable("url") String url, @SpringQueryMap Object params);
    @PutMapping(value = "{url}")
    String executePutRequest(@PathVariable("url") String url, @RequestBody Object params);
    @DeleteMapping(value = "{url}")
    String executeDeleteRequest(@PathVariable("url") String url, @RequestBody Object params);
}

/**
 * Description: FeignClient工厂类,根据服务名称创建FeignClient对象(代理对象)
 */
@Component
public class DynamicFeignClientFactory <T>{
    private FeignClientBuilder feignClientBuilder;
    public DynamicFeignClientFactory(ApplicationContext applicationContext){
        this.feignClientBuilder = new FeignClientBuilder(applicationContext);
    }
    //动态生成feignClient对象(代理对象)
    public T getFeignClient(final Class<T> type,String ServiceID){
        return this.feignClientBuilder.forType(type,ServiceID).build();
    }
}

/**
 * Description: 通过FeignClient工厂获取到的FeignClient对象通过指定的请求去调用生产者方法!
 */
@Component
public class DynamicClient {
    @Autowired
    private DynamicFeignClientFactory<DynamicService> dynamicDynamicFeignClientFactory;
    public Object executePostApi(String feignName,String url,Object params){
        DynamicService dynamicService = dynamicDynamicFeignClientFactory.getFeignClient(DynamicService.class,feignName);
        return dynamicService.executePostRequest(url,params);
    }
    public Object executeGetApi(String feignName,String url,Object params){
        DynamicService dynamicService = dynamicDynamicFeignClientFactory.getFeignClient(DynamicService.class,feignName);
        return dynamicService.executeGetRequest(url, params);
    }
    //省略了两个方法...
}

<dependency>
            <groupId>com.xp</groupId>
            <artifactId>dynamic-feign</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

@RestController
public class UserController {
    //注入动态FeignClient对象
    @Autowired
    private DynamicClient dynamicClient;
    @GetMapping(value = "/getorder/{oid}")
    public Object getOrderById(@PathVariable(value = "oid") String oid) {
        //通过动态FeignClient,指定服务名称,Handler方法URL,参数等信息即可调用生产者对应的方法
        return this.dynamicClient.executeGetApi("cloud-order", "/getOrderById/".concat(oid),new HashMap<>());
    }
    @PostMapping(value = "/addOrder")
    public Object addOrder(@RequestBody Map<String,Object> map){
        return this.dynamicClient.executePostApi("cloud-order", "/addOrder", map);
    }
}

@SpringBootApplication
@EnableDiscoveryClient   //服务治理
@EnableFeignClients //开启Feign功能(不写也可以!)
public class UserApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserApplication.class,args);
    }
}