如何在Spring Boot服务应用程序中的REST服务调用之间按原样传递请求参数？

时间：2019-03-21 11:30:57

标签： spring rest spring-boot refactoring microservices

我们正在进行体系结构重构，以将单片J2EE EJB应用程序转换为Spring服务。为了做到这一点，我正在通过将应用程序与其领域的联合破坏来创建服务。目前，我有三个人，每个人都通过Rest呼叫另一个服务。

在这个项目中，我们的最终目的是将应用程序转换为微服务，但是由于云基础架构尚不明确并且可能无法实现，因此我们决定采用这种方式，并认为既然服务使用Rest，将来很容易进行转换。

我们的方法有意义吗？我的问题源于此。

我通过Postman的标头参数userName向UserService发送请求。

GET http://localhost:8087/users/userId?userName=12345

UserService调用另一个服务，后者又调用另一个服务。服务之间的剩余呼叫顺序是这样的：

UserService ---REST--> CustomerService ---REST--> AlarmService

由于我现在正在进行像这样的通用请求参数的工作，因此我需要在发出Rest请求的每种方法中都将通用标头参数设置为从传入请求到传出请求的方式：

@RequestMapping(value="/users/userId", method = RequestMethod.GET)
public ResponseEntity<Long> getUserId(@RequestHeader("userName") String userName) {
    ...
        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Collections.singletonList
(MediaType.APPLICATION_JSON));

        headers.set("userName", userName);

        HttpEntity<String> entity = new HttpEntity<>("parameters", headers);
        HttpEntity<Long> response =
                restTemplate.exchange(CUSTOMER_REST_SERVICE_URI,
                HttpMethod.GET, entity, Long.class);
     ...
 }

UserService： 

package com.xxx.userservice.impl;

import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.*;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.Collections;
import java.util.Map;

@RestController
public class UserController  extends AbstractService{

    Logger logger = Logger.getLogger(UserController.class.getName());

    @Autowired
    private RestTemplate restTemplate;

    private final String CUSTOMER_REST_SERVICE_HOST = "http://localhost:8085";
    private final String CUSTOMER_REST_SERVICE_URI = CUSTOMER_REST_SERVICE_HOST + "/customers/userId";

    @RequestMapping(value="/users/userId", method = RequestMethod.GET)
    public ResponseEntity<Long> getUserId(@RequestHeader("userName") String userName) {
        logger.info(""user service is calling customer service..."");
        try {

            //do the internal customer service logic

            //call other service.
            HttpHeaders headers = new HttpHeaders();
            headers.setAccept(Collections.singletonList
(MediaType.APPLICATION_JSON));
            headers.set("userName", userName);
            HttpEntity<String> entity = new HttpEntity<>("parameters", headers);

            HttpEntity<Long> response =
                    restTemplate.exchange(CUSTOMER_REST_SERVICE_URI,
                    HttpMethod.GET, entity, Long.class);

            return ResponseEntity.ok(response.getBody());
        } catch (Exception e) {
            logger.error("user service could not call customer service: ", e);
            throw new RuntimeException(e);
        }
        finally {
            logger.info("customer service called...");
        }
    }

}

CustomerService： 

package com.xxxx.customerservice.impl;

import java.rmi.RemoteException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.xxx.interf.CustomerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class CustomerController  extends AbstractService{

    private final String ALARM_REST_SERVICE_HOST = "http://localhost:8086";
    private final String ALARM_REST_SERVICE_URI = ALARM_REST_SERVICE_HOST + "/alarms/maxAlarmCount";

    @Autowired
    private CustomerService customerService;

    @Autowired
    private RestTemplate restTemplate;

    ...

    @GetMapping(path="/customers/userId", produces = "application/json")
    public long getUserId(@RequestHeader(value="Accept") String acceptType) throws RemoteException {

        //customer service internal logic.
        customerService.getUserId();

        //customer service calling alarm service.
        return restTemplate.getForObject(ALARM_REST_SERVICE_URI, Long.class);

    }

}

AlarmService： 

package com.xxx.alarmservice.impl;

import com.xxx.interf.AlarmService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class PriceAlarmController extends AbstractService{

    @Autowired
    private AlarmService priceAlarmService;

    @RequestMapping("/alarms/maxAlarmCount")
    public long getMaxAlarmsPerUser() {

        // alarm service internal logic.
        return priceAlarmService.getMaxAlarmsPerUser();
    }

}

我已经尝试过这些配置和拦截器文件，但是我可以将它们仅用于记录日志，而不能通过使用它们来传输头参数。可能是因为每个服务都有它们。而且，此拦截器仅在UserService中起作用，后者首先使用RestTemplate发送请求。来自Postman的被调用服务和第一个请求无法使用，因为它们不会像UserService一样打印任何日志消息。

CommonModule： 

package com.xxx.common.config;

import com.xxx.common.util.HeaderRequestInterceptor;
import org.apache.cxf.common.util.CollectionUtils;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.web.client.RestTemplate;

import java.util.ArrayList;
import java.util.List;

@Configuration
public class RestTemplateConfig {

    @Bean
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();

        List<ClientHttpRequestInterceptor> interceptors
                = restTemplate.getInterceptors();
        if (CollectionUtils.isEmpty(interceptors)) {
            interceptors = new ArrayList<>();
        }
        interceptors.add(new HeaderRequestInterceptor());
        restTemplate.setInterceptors(interceptors);
        return restTemplate;
    }
}

ClientHttpRequestInterceptor：


package com.xxx.common.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpRequest;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpRequestExecution;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.util.StreamUtils;

import java.io.IOException;
import java.nio.charset.Charset;

public class HeaderRequestInterceptor implements ClientHttpRequestInterceptor {

    private final Logger log = LoggerFactory.getLogger(this.getClass());

    @Override
    public ClientHttpResponse intercept(
            HttpRequest request,
            byte[] body,
            ClientHttpRequestExecution execution) throws IOException
    {
        log.info("HeaderRequestInterceptor....");
        logRequest(request, body);
        request.getHeaders().set("Accept", MediaType.APPLICATION_JSON_VALUE);

        ClientHttpResponse response = execution.execute(request, body);
        logResponse(response);

        return response;
    }

    private void logRequest(HttpRequest request, byte[] body) throws IOException
    {
        log.info("==========request begin=======================");
    }

    private void logResponse(ClientHttpResponse response) throws IOException
    {
        log.info("==========response begin=============");
    }

}

如何通过在单个位置使用某种拦截器或其他机制来管理诸如userName之类的通用标头信息的传递？

1 个答案:

答案 0 :(得分：0)

在HeaderRequestInterceptor的拦截方法中，您可以通过以下方式访问当前的http请求及其标题（在您的情况下为userId）：

@Override
public ClientHttpResponse intercept(HttpRequest request..
...
   HttpServletRequest httpServletRequest = ((ServletRequestAttributes) RequestContextHolder.currentRequestAttributes()).getRequest();
   String userId = httpServletRequest.getHeader("userId");
   request.getHeaders().set("userId", userId);
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