springboot单独使用feign简化http接口调用(参考项目java-video)

前言

与HttpClient和RestTemplate相比，使用springcloud的feign调用远程接口更为简便，可以通过配置的方式实现远程接口调用。但是有时我们并不想使用springcloud，而只是想在springboot中使用feign,我在网上搜了很多springboot单独集成feign的文章,但都不能用。在通过学习、开发后简单整理了一个教程。详细介绍如何在springboot中单独集成feign，以简便的方式调用远程接口。

1. 引用maven

   <groupId>com.examplegroupId>
    <artifactId>demoartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <packaging>jarpackaging>

    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.2.2.RELEASEversion>
        <relativePath/>
    parent>

    <properties>
        <java.version>1.8java.version>
        <maven.compiler.target>1.8maven.compiler.target>
        <maven.compiler.source>1.8maven.compiler.source>
        
        <spring-cloud.version>Hoxton.SR1spring-cloud.version>
    properties>

    <dependencies>
         <dependency>
            <groupId>org.springframework.bootgroupId>
              <artifactId>spring-boot-dependenciesartifactId>
              <version>2.2.2.RELEASEversion>
              <type>pomtype>
              <scope>importscope>
         dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starterartifactId>
        dependency>

        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>

        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-openfeignartifactId>
        dependency>

    dependencies>
    
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>${spring-cloud.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>

2. 启动类添加@EnableFeignClients注解，开启feign

@EnableFeignClients //开启feign
@SpringBootApplication
public class SpringbootApplication {
	public static void main(String[] args) {
		SpringApplication.run(SpringbootApplication.class, args);
	}
}

3. 像平常一样写一个rpc接口, 在此基础上不回一些feign注释和失败后回调的地址

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestHeader;
import feign.Response;

@FeignClient(name = "userService", url = "${feign.rpc.systemServiceOne}", configuration = FeignConfig.class, fallbackFactory = RemoteUserRpcFallbackFactory.class)
public interface RemoteUserRpc {

    @PostMapping(value = "/person",consumes = MediaType.APPLICATION_JSON_VALUE)
    R<UserEntity> getUserInfo(@RequestBody UserEntity user);

	//另外一种用Response接收
	@PutMapping(value = "/x_organization_assemble_personal/jaxrs/person/icon", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    Response updateIcon(@RequestPart("file") MultipartFile file, @RequestParam("fileName") String fileName);
}

@FeginClient中的name是自己给这个rpc起的名字, ur为调用的地址

4. 写一个feignServcie调用此接口

    /**
     * 获取用户信息
     *
     * @return the user info
     */
    public UserEntity getUserInfo(UserEntity user) {
        R<UserEntity> r = remoteUserRpc.getUserInfo(user);
        if (r.getCode() == HttpStatus.ERROR) {
            throw new RuntimeException(r.getMessage());
        }
        return r.getData();
    }
    
    /**
     * 更新用户头像
     *
     * @param file     the file
     * @param fileName the file name
     */
    public void updateIcon(MultipartFile file, String fileName) {
        Response response = remoteUserRpc.updateIcon(file, fileName);

        String str = HttpUtils.inputStreamConvertStr(response);
        R r = JSONObject.parseObject(str, R.class);

        String type = r.getType();
        if (r.getCode() == HttpStatus.ERROR || !type.equals(ThirdStatus.SUCCESS)) {
            throw new RuntimeException(r.getMessage());
        }
    }

response 转str 工具类

    /**
     * 流转str
     *
     * @param response the response
     * @return string string
     */
    public static String inputStreamConvertStr(Response response) {

        Response.Body body = response.body();
        String str = null;
        try {
            InputStream inputStream = body.asInputStream();
            StringBuilder sb = new StringBuilder();
            String line;

            BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
            while ((line = br.readLine()) != null) {
                sb.append(line);
            }
            str = sb.toString();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }

5. 用到的接收数据的请示体

/**
 * 响应信息主体
 *
 * @author lxy
 */
@Data
public class R<T> implements Serializable {
    private static final long serialVersionUID = 1L;

    /**
     * 成功
     */
    public static final int SUCCESS = Constants.SUCCESS;

    /**
     * 失败
     */
    public static final int FAIL = Constants.FAIL;

    private int code;

    private String msg;

    private T data;


    public static <T> R2<T> ok() {
        return restResult(null, SUCCESS, null);
    }

    public static <T> R2<T> ok(T data) {
        return restResult(data, SUCCESS, null);
    }

    public static <T> R2<T> ok(T data, String msg) {
        return restResult(data, SUCCESS, msg);
    }

    public static <T> R2<T> fail() {
        return restResult(null, FAIL, null);
    }

    public static <T> R2<T> fail(String msg) {
        return restResult(null, FAIL, msg);
    }

    public static <T> R2<T> fail(T data) {
        return restResult(data, FAIL, null);
    }

    public static <T> R2<T> fail(T data, String msg) {
        return restResult(data, FAIL, msg);
    }

    public static <T> R2<T> fail(int code, String msg) {
        return restResult(null, code, msg);
    }

    private static <T> R2<T> restResult(T data, int code, String msg) {
        R2<T> apiResult = new R2<>();
        apiResult.setCode(code);
        apiResult.setData(data);
        apiResult.setMsg(msg);
        return apiResult;
    }
}

6. feign失败后的回调

import feign.hystrix.FallbackFactory;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class RemoteUserRpcFallbackFactory implements FallbackFactory<RemoteUserRpc> {

    @Override
    public RemoteUserRpc create(Throwable throwable) {
        log.error("调用用户数据接口出错:{}", throwable.getMessage());
        return new RemoteUserRpc() {
            @Override
            public R<UserEntity> getUserInfo(UserEntity user) {
                return R.fail("调用用户数据接口出错:" + throwable.getMessage());
            }
            @Override
            public Response updateIcon(MultipartFile file, String fileName) {
                return null;
            }
        };
    }
}

如果在通过feign调用的时候需要在请示头中添加token的话有两种方式, 一种是在feign中添加

    @PostMapping(value = "/person",consumes = MediaType.APPLICATION_JSON_VALUE)
    R getUserInfo(@RequestHeader Map header, @RequestBody UserEntity user);

但这种方式需要在每次请示的时候获取token放到header中(不推荐), 比较麻烦, 还有一种是设置feign拦截器,进行相应header的转发(推荐)

/**
 * feign转发header参数
 */
@Configuration
public class FeignConfig implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate requestTemplate) {
        HttpServletRequest httpServletRequest = ServletUtils.getRequest();
        if (StringUtils.isNotNull(httpServletRequest)) {
            Map<String, String> headers = ServletUtils.getHeaders(httpServletRequest);

            String authentication = headers.get(Constants.AUTHORIZATION_HEADER);
            if (StringUtils.isNotEmpty(authentication)) {
                requestTemplate.header(Constants.AUTHORIZATION_HEADER, authentication);
            }
        }
    }
}

跟这个feignConfig相关的工具类

/**
 * 客户端工具类
 */
public class ServletUtils {
    /**
     * 获取request
     */
    public static HttpServletRequest getRequest() {
        try {
            return getRequestAttributes().getRequest();
        } catch (Exception e) {
            return null;
        }
    }
    public static ServletRequestAttributes getRequestAttributes() {
        try {
            RequestAttributes attributes = RequestContextHolder.getRequestAttributes();
            return (ServletRequestAttributes) attributes;
        } catch (Exception e) {
            return null;
        }
    }
}

但只有这feginConfig还不行, 还需要配置feign隔离策略, 不然会造成request里面获取不到信息

import com.netflix.hystrix.HystrixThreadPoolKey;
import com.netflix.hystrix.HystrixThreadPoolProperties;
import com.netflix.hystrix.strategy.HystrixPlugins;
import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariable;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariableLifecycle;
import com.netflix.hystrix.strategy.eventnotifier.HystrixEventNotifier;
import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;
import com.netflix.hystrix.strategy.metrics.HystrixMetricsPublisher;
import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
import com.netflix.hystrix.strategy.properties.HystrixProperty;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
 
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
 
/**
 * 自定义Feign的隔离策略:
 *   在转发Feign的请求头的时候, 如果开启了Hystrix, 
 *      Hystrix的默认隔离策略是Thread(线程隔离策略), 因此转发拦截器内是无法获取到请求的请求头信息的, 
 *      可以修改默认隔离策略为信号量模式：hystrix.command.default.execution.isolation.strategy=SEMAPHORE, 
 *      这样的话转发线程和请求线程实际上是一个线程, 这并不是最好的解决方法, 信号量模式也不是官方最为推荐的隔离策略;
 *   另一个解决方法就是自定义Hystrix的隔离策略:
 *      思路是将现有的并发策略作为新并发策略的成员变量,在新并发策略中, 
 *      返回现有并发策略的线程池、Queue;将策略加到Spring容器即可;
 */
@Component
public class FeignHystrixConcurrencyStrategyIntellif extends HystrixConcurrencyStrategy {
    Logger log = LoggerFactory.getLogger(this.getClass());
 
    private HystrixConcurrencyStrategy delegate;
 
    public FeignHystrixConcurrencyStrategyIntellif() {
        try {
            this.delegate = HystrixPlugins.getInstance().getConcurrencyStrategy();
            if (this.delegate instanceof FeignHystrixConcurrencyStrategyIntellif) {
                // Welcome to singleton hell...
                return;
            }
 
            HystrixCommandExecutionHook commandExecutionHook =
                    HystrixPlugins.getInstance().getCommandExecutionHook();
 
            HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance().getEventNotifier();
            HystrixMetricsPublisher metricsPublisher = HystrixPlugins.getInstance().getMetricsPublisher();
            HystrixPropertiesStrategy propertiesStrategy =
                    HystrixPlugins.getInstance().getPropertiesStrategy();
            this.logCurrentStateOfHystrixPlugins(eventNotifier, metricsPublisher, propertiesStrategy);
 
            HystrixPlugins.reset();
            HystrixPlugins instance = HystrixPlugins.getInstance();
            instance.registerConcurrencyStrategy(this);
            instance.registerCommandExecutionHook(commandExecutionHook);
            instance.registerEventNotifier(eventNotifier);
            instance.registerMetricsPublisher(metricsPublisher);
            instance.registerPropertiesStrategy(propertiesStrategy);
        } catch (Exception e) {
            log.error("Failed to register Sleuth Hystrix Concurrency Strategy", e);
        }
    }
 
    private void logCurrentStateOfHystrixPlugins(HystrixEventNotifier eventNotifier,
                                                 HystrixMetricsPublisher metricsPublisher,
                                                 HystrixPropertiesStrategy propertiesStrategy) {
        if (log.isDebugEnabled()) {
            log.debug("Current Hystrix plugins configuration is [" + "concurrencyStrategy ["
                    + this.delegate + "]," + "eventNotifier [" + eventNotifier + "]," + "metricPublisher ["
                    + metricsPublisher + "]," + "propertiesStrategy [" + propertiesStrategy + "]," + "]");
            log.debug("Registering Sleuth Hystrix Concurrency Strategy.");
        }
    }
 
    @Override
    public <T> Callable<T> wrapCallable(Callable<T> callable) {
        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
        return new WrappedCallable<>(callable, requestAttributes);
    }
 
    @Override
    public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey,
                                            HystrixProperty<Integer> corePoolSize,
                                            HystrixProperty<Integer> maximumPoolSize,
                                            HystrixProperty<Integer> keepAliveTime,
                                            TimeUnit unit, BlockingQueue<Runnable> workQueue) {
        return this.delegate.getThreadPool(threadPoolKey, corePoolSize, maximumPoolSize, keepAliveTime,
                unit, workQueue);
    }
 
    @Override
    public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey,
                                            HystrixThreadPoolProperties threadPoolProperties) {
        return this.delegate.getThreadPool(threadPoolKey, threadPoolProperties);
    }
 
    @Override
    public BlockingQueue<Runnable> getBlockingQueue(int maxQueueSize) {
        return this.delegate.getBlockingQueue(maxQueueSize);
    }
 
    @Override
    public <T> HystrixRequestVariable<T> getRequestVariable(HystrixRequestVariableLifecycle<T> rv) {
        return this.delegate.getRequestVariable(rv);
    }
 
    static class WrappedCallable<T> implements Callable<T> {
        private final Callable<T> target;
        private final RequestAttributes requestAttributes;
 
        public WrappedCallable(Callable<T> target, RequestAttributes requestAttributes) {
            this.target = target;
            this.requestAttributes = requestAttributes;
        }
 
        @Override
        public T call() throws Exception {
            try {
                RequestContextHolder.setRequestAttributes(requestAttributes);
                return target.call();
            } finally {
                RequestContextHolder.resetRequestAttributes();
            }
        }
    }
}

注意: FallbackFactory不要引错, 要引import feign.hystrix.FallbackFactory;这个包路径下的,否则会有问题

7. 配置文件配置

#是否开启hystrix。true：开启，false：不开启, 不开启的话feign调用失败不回走到回调函数里面
feign:
  hystrix:
    enabled: true
  rpc:
    systemServiceOne: http://192.168.0.182:20020
#hystrixf超时时间, 不设置feign调用会很快超时
hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 10000