Springcloud Eureka详解

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Springcloud Eureka详解

Eureka Server 详解

  1. pom依赖

    <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>

  2. 配置文件

    spring:
  application:
    name: springcloud-demo-eureka-server


eureka:
  client:
    # server端也是一个客户端，需要注册到服务端，需要配置服务端的地址
    service-url:
      defaultZone: http://localhost:8762/eureka/
    # 是否需要将该服务注册到服务端,自己就是服务端，不用注册自己
    register-with-eureka: false
    # 是否同步其他server的注册信息，当有多个Eureka Server端时，需要同步信息
    fetch-registry: false
  # 关掉自我保护，由于服务上线率低，会有警告提示，会认为该服务是在线的，即使该服务已经掉线了。
  server:
    enable-self-preservation: false
server:
  port: 8762

  3. 启动类配置注解@EnableEurekaServer

    @SpringBootApplication
@EnableEurekaServer
public class EurekaServer {
    public static void main(String[] args) {
        SpringApplication.run(EurekaServer.class, args);
    }
}

  4. 访问地址http://localhost:8762，可以看到界面

Euraka Client详解

  1. pom依赖

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

    • 作为eureka 客户端，依赖spring-cloud-starter-netflix-eureka-client

    • 对外要提供服务，所以要提供spring-boot-starter-web（没有就会报错，无法启动,204）

      2020-04-14 11:30:28.271  INFO 33156 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRINGCLOUD-DEMO-PROVIER/localhost:springcloud-demo-provier:8091 - registration status: 204
  2020-04-14 11:30:28.272  INFO 33156 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRINGCLOUD-DEMO-PROVIER/localhost:springcloud-demo-provier:8091: registering service...
  2020-04-14 11:30:28.277  INFO 33156 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRINGCLOUD-DEMO-PROVIER/localhost:springcloud-demo-provier:8091 - registration status: 204
  2020-04-14 11:30:28.277  INFO 33156 --- [extShutdownHook] com.netflix.discovery.DiscoveryClient    : Unregistering ...
  2020-04-14 11:30:28.283  INFO 33156 --- [extShutdownHook] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_SPRINGCLOUD-DEMO-PROVIER/localhost:springcloud-demo-provier:8091 - deregister  status: 200

  2. 配置文件

    spring:
  application:
    name: springcloud-demo-provier
server:
  port: 8091


eureka:
  client:
    # eureka服务端的地址	
    service-url:
      defaultZone: http://localhost:8762/eureka

  3. 启动类配置注解@EnableEurekaClient

@SpringBootApplication
@EnableEurekaClient
public class ProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(ProviderApplication.class, args);
    }
}
  1. 访问地址http://localhost:8762

可以看到用该服务已经注册到eureka服务端

服务间通信

Feign

提供者

  1. pom依赖

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

  2. 服务对外暴露接口信息

    @FeignClient(value = "springcloud-demo-provier")
public interface ProviderApiClient {

    @GetMapping("/provider/info")
    String info(@RequestParam("msg") String msg);

    @PostMapping("/provider/userinfo")
    String userInfo(@RequestBody User user);
}

    其他服务通过注入ProviderApiClient类，调用info方法，从而间接调用对应的接口。

    注意：

    1. @FeignClient value值是该服务的名称
    2. 参数需要用注解标明，@RequestParam/@PathVariable/@RequestHeader等来构造http请求。

  3. 接口

    @RestController
@RequestMapping("/provider")
public class ProviderController {

    @GetMapping("/info")
    public String info(@RequestParam("msg") String msg) {
        return "springcloud-demo-provider info ----- " + msg;
    }


    @PostMapping("/userinfo")
    public String userInfo(@RequestBody User user) {
        return user.toString();
    }
}

消费者

  1. pom依赖

    <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency>
    <groupId>com.wc</groupId>
    <artifactId>springcloud-demo-provider</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <scope>compile</scope>
</dependency>

    依赖openFeign还要依赖FeignClient所在服务的jar.

  2. 启动类需要标注@EnableFeignClients(basePackages = {"com.wc.api"})，basePackages的值是@FeignClient注解的类所在的包名

  3. 接口

    @RestController
@RequestMapping("/consumer")
public class ConsumerController {

    @Autowired
    private ProviderApiClient providerApiClient;

    @GetMapping("/info")
    public String info(@RequestParam("msg") String msg) {
        System.out.println("ConsumerController msg: " + msg);
        return providerApiClient.info(msg);

    }


    @PostMapping("/userinfo")
    public String userInfo(@RequestBody User user) {
        return providerApiClient.userInfo(user);

    }
}

    注入服务提供者的接口，调用方法。

参考链接：

  1. blog.csdn.net/russle/arti…

RestTemplate

  1. 配置restTemplate，@LoadBalanced注解是从Ribbon负载均衡器，从所有的目标服务中按照自己配置的规则找到对应的服务。

    @Component
public class RestTemplateConfig {

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

  2. get请求调用

    @RestController
@RequestMapping("/consumer")
public class ConsumerController {
    @Autowired
    private RestTemplate restTemplate;

    private static final String URL = "http://SPRINGCLOUD-DEMO-PROVIER";

    @GetMapping("/restinfo")
    public String restInfo(@RequestParam("msg") String msg) {
        String url = String.format(URL + "/provider/info?msg=%s", msg);
        return restTemplate.getForObject(url, String.class);
    }
    
    @GetMapping("/restinfo/{id}")
    public String restInfo(@PathVariable("id" Integer id)) {
        return restTemplate.getForObject(URL + "/provider/info/{id}",
                                         String.class,
                                         id);
    }
}

    如果传参值在请求路径中，调用这个方法，后面的参数是请求路径中的参数

    T getForObject(String url, Class responseType, Object... uriVariables) throws RestClientException;

  3. post请求

    如果是请求体传参，直接透传，提供者接口也是使用@RequestBody接收

        @PostMapping("/rest-userinfo2")
    public String restUserInfo2(@RequestBody User user) {

        return restTemplate.postForObject(URL + "/provider/userinfo", 
                                          user, 
                                          String.class);

    }

    如果是表单传参，稍微复杂一点，需要设置content-type。

        public String restUserInfo1(User user) {
        HttpHeaders headers = new HttpHeaders();
        //  请勿轻易改变此提交方式，大部分的情况下，提交方式都是表单提交
        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
        
        //  封装参数，千万不要替换为Map与HashMap，否则参数无法传递
        MultiValueMap<String, String> params = 
            new LinkedMultiValueMap<String, String>();
        
        //  也支持中文
        params.add("name", user.getName());
        params.add("age", user.getAge().toString());
        
        HttpEntity<MultiValueMap<String, String>> requestEntity = 
            new HttpEntity<MultiValueMap<String, String>>(params, headers);
        
        //  执行HTTP请求
        return restTemplate.postForObject(URL + "/provider/userinfo", 
                                          requestEntity, 
                                          String.class);

    }

    自定义MessageConverter,继承MappingJackson2HttpMessageConverter

    public class MyMessageConverter extends MappingJackson2HttpMessageConverter {
    public MyMessageConverter() {
        List<MediaType> list = new ArrayList<>();
        list.add(MediaType.TEXT_PLAIN);
        list.add(MediaType.TEXT_HTML);
        setSupportedMediaTypes(list);
    }
}

        @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.getMessageConverters().add(new MyMessageConverter());
        return restTemplate;
    }

    RestTemplate中的方法详细参考：

    github.com/vieyahn2017…

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