SpringCloud生产消费者

时间  2020-07-23
标签 springcloud 生产 消费者 繁體版
原文   原文链接

SpringCloud生产消费者

生产者与消费者

上一篇文章介绍了Euarka的搭建，SpringCloud服务注册中心
本篇文章，咱们搭建俩个服务，生产者服务与消费者服务。java

本文就以电商系统为例：服务生产者，订单查询服务order-server，服务消费者order-clientweb

说明：order-server 服务提供查询订单信息的功能
order-client做为消费者服务，查询订单信息。spring

生产者服务搭建

选择咱们须要的依赖,具体依赖以下浏览器

<dependency>
  <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

spring-cloud-starter-netflix-eureka-client 表示该服务是一个eureka的客户端
订单服务会注册到eureka服务端上app

依赖添加完成后，咱们须要在SpringBoot项目的入口类上加上
@EnableDiscoveryClient注解框架

表示开启服务注册到eureka服务上ide

@SpringBootApplication
@EnableDiscoveryClient
public class OrderServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderServiceApplication.class, args);
    }

}

接下来，须要咱们对订单服务进行必要的配置spring-boot

server:
  port: 8081

spring:
  application:
    name: order-service

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka

说明：server.prot:订单服务的端口源码分析

spring.application.name:订单服务的名称，post

这个名称会注册到eureka服务上

eureka.client.service-url.defaultZone:eureka服务的地址。

通过简单的配置之后，咱们启动服务，访问eureka服务,http://localhost:8761，以下图：

咱们将订单服务以及注册到eureka服务上了。此事，
咱们提供一个订单查询的接口，模拟订单查询功能。

@RestController
@RequestMapping("query")
public class OrderQueryController {
    @Autowired
    OrderQueryService queryService;

    @RequestMapping("info")
    public String queryOrder(){
        return queryService.queryOrder();
    }
}


@Service
public class OrderQueryService {

    public String queryOrder(){
        return "订单信息查询成功";
    }
}

消费者服务搭建

只须要像搭建服务提供者同样搭建服务消费者就能够，
搭建完成之后，咱们使用RestTemplate
来调用订单服务进行订单信息查询，具体配置及代码以下：

server:
  port: 8082

spring:
  application:
    name: order-client

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka
//提供一个RestTemplate实例
@SpringBootApplication
@EnableDiscoveryClient
public class OrderClientApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderClientApplication.class, args);
    }

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

//编写测试接口
@RestController
public class ClientController {
    @Autowired
    ClientService clientService;

    @RequestMapping(value = "/info",method = RequestMethod.GET)
    public String queryOrderInfo(){
        return "restTemplate访问服务提供者返回的信息:"+clientService.queryOrderInfo();
    }
}

//模拟具体查询业务逻辑
@Service
public class ClientService {

    @Autowired
    RestTemplate restTemplate;

    public String queryOrderInfo(){
        System.out.println("经过restTemplate访问服务提供者");
        return restTemplate.getForEntity("http://ORDER-SERVER/query/info", 			  String.class).getBody();
    }

}

RestTemplate 介绍：
是spring框架提供的可用于在应用中调用rest服务，它简化了与http服务的通讯方式，统一了RESTful的标准，封装了http连接， 咱们只须要传入url及返回值类型便可。相较于以前经常使用的HttpClient，RestTemplate是一种更优雅的调用RESTful服务的方式。

源码分析

部分源码以下，能够看出，它包含了Get、Post、Put等请求，好比Get请求包含俩种方法getForObject、getForEntity,他们有什么区别呢？

  • 从接口的签名上，能够看出一个是直接返回预期的对象，一个则是将对象包装到 ResponseEntity 封装类中
  • 若是只关心返回结果，那么直接用 getForObject 便可
  • 若是除了返回的实体内容以外，还须要获取返回的header等信息，则可使用 getForEntity
@Override
	@Nullable
	public <T> T getForObject(String url, Class<T> responseType, Object... uriVariables) throws RestClientException {
		RequestCallback requestCallback = acceptHeaderRequestCallback(responseType);
		HttpMessageConverterExtractor<T> responseExtractor =
				new HttpMessageConverterExtractor<>(responseType, getMessageConverters(), logger);
		return execute(url, HttpMethod.GET, requestCallback, responseExtractor, uriVariables);
	}

	@Override
	@Nullable
	public <T> T getForObject(String url, Class<T> responseType, Map<String, ?> uriVariables) throws RestClientException {
		RequestCallback requestCallback = acceptHeaderRequestCallback(responseType);
		HttpMessageConverterExtractor<T> responseExtractor =
				new HttpMessageConverterExtractor<>(responseType, getMessageConverters(), logger);
		return execute(url, HttpMethod.GET, requestCallback, responseExtractor, uriVariables);
	}

	@Override
	@Nullable
	public <T> T getForObject(URI url, Class<T> responseType) throws RestClientException {
		RequestCallback requestCallback = acceptHeaderRequestCallback(responseType);
		HttpMessageConverterExtractor<T> responseExtractor =
				new HttpMessageConverterExtractor<>(responseType, getMessageConverters(), logger);
		return execute(url, HttpMethod.GET, requestCallback, responseExtractor);
	}

	@Override
	public <T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Object... uriVariables)
			throws RestClientException {

		RequestCallback requestCallback = acceptHeaderRequestCallback(responseType);
		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(responseType);
		return nonNull(execute(url, HttpMethod.GET, requestCallback, responseExtractor, uriVariables));
	}

	@Override
	public <T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Map<String, ?> uriVariables)
			throws RestClientException {

		RequestCallback requestCallback = acceptHeaderRequestCallback(responseType);
		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(responseType);
		return nonNull(execute(url, HttpMethod.GET, requestCallback, responseExtractor, uriVariables));
	}

	@Override
	public <T> ResponseEntity<T> getForEntity(URI url, Class<T> responseType) throws RestClientException {
		RequestCallback requestCallback = acceptHeaderRequestCallback(responseType);
		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(responseType);
		return nonNull(execute(url, HttpMethod.GET, requestCallback, responseExtractor));
	}


	// HEAD

	@Override
	public HttpHeaders headForHeaders(String url, Object... uriVariables) throws RestClientException {
		return nonNull(execute(url, HttpMethod.HEAD, null, headersExtractor(), uriVariables));
	}

	@Override
	public HttpHeaders headForHeaders(String url, Map<String, ?> uriVariables) throws RestClientException {
		return nonNull(execute(url, HttpMethod.HEAD, null, headersExtractor(), uriVariables));
	}

	@Override
	public HttpHeaders headForHeaders(URI url) throws RestClientException {
		return nonNull(execute(url, HttpMethod.HEAD, null, headersExtractor()));
	}


	// POST

	@Override
	@Nullable
	public URI postForLocation(String url, @Nullable Object request, Object... uriVariables)
			throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request);
		HttpHeaders headers = execute(url, HttpMethod.POST, requestCallback, headersExtractor(), uriVariables);
		return (headers != null ? headers.getLocation() : null);
	}

	@Override
	@Nullable
	public URI postForLocation(String url, @Nullable Object request, Map<String, ?> uriVariables)
			throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request);
		HttpHeaders headers = execute(url, HttpMethod.POST, requestCallback, headersExtractor(), uriVariables);
		return (headers != null ? headers.getLocation() : null);
	}

	@Override
	@Nullable
	public URI postForLocation(URI url, @Nullable Object request) throws RestClientException {
		RequestCallback requestCallback = httpEntityCallback(request);
		HttpHeaders headers = execute(url, HttpMethod.POST, requestCallback, headersExtractor());
		return (headers != null ? headers.getLocation() : null);
	}

	@Override
	@Nullable
	public <T> T postForObject(String url, @Nullable Object request, Class<T> responseType,
			Object... uriVariables) throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request, responseType);
		HttpMessageConverterExtractor<T> responseExtractor =
				new HttpMessageConverterExtractor<>(responseType, getMessageConverters(), logger);
		return execute(url, HttpMethod.POST, requestCallback, responseExtractor, uriVariables);
	}

	@Override
	@Nullable
	public <T> T postForObject(String url, @Nullable Object request, Class<T> responseType,
			Map<String, ?> uriVariables) throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request, responseType);
		HttpMessageConverterExtractor<T> responseExtractor =
				new HttpMessageConverterExtractor<>(responseType, getMessageConverters(), logger);
		return execute(url, HttpMethod.POST, requestCallback, responseExtractor, uriVariables);
	}

	@Override
	@Nullable
	public <T> T postForObject(URI url, @Nullable Object request, Class<T> responseType)
			throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request, responseType);
		HttpMessageConverterExtractor<T> responseExtractor =
				new HttpMessageConverterExtractor<>(responseType, getMessageConverters());
		return execute(url, HttpMethod.POST, requestCallback, responseExtractor);
	}

	@Override
	public <T> ResponseEntity<T> postForEntity(String url, @Nullable Object request,
			Class<T> responseType, Object... uriVariables) throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request, responseType);
		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(responseType);
		return nonNull(execute(url, HttpMethod.POST, requestCallback, responseExtractor, uriVariables));
	}

	@Override
	public <T> ResponseEntity<T> postForEntity(String url, @Nullable Object request,
			Class<T> responseType, Map<String, ?> uriVariables) throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request, responseType);
		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(responseType);
		return nonNull(execute(url, HttpMethod.POST, requestCallback, responseExtractor, uriVariables));
	}

	@Override
	public <T> ResponseEntity<T> postForEntity(URI url, @Nullable Object request, Class<T> responseType)
			throws RestClientException {

		RequestCallback requestCallback = httpEntityCallback(request, responseType);
		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(responseType);
		return nonNull(execute(url, HttpMethod.POST, requestCallback, responseExtractor));
	}

接下来，咱们启动，服务消费者，
此时访问咱们的eureka服务，
已经有俩个服务注册上来了，以下：

最后咱们来验证一下，服务消费者是否能调用到服务提供者，
在浏览器输出http://localhost:8082/info

根据返回的信息，确认服务调用成功。

小结

以上就是咱们基于eureka的服务注册发现机制，实现的服务之间的相互调用。
固然，这里边还有不少的细节须要讨论，后续的文章，继续和你们讨论。

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