SpringCloud 服务通信方法

eureka 服务已经启动  http://localhost:8761/

注: 在启动文件加上 注解

@EnableEurekaServer 
application.yml 配置文件

eureka:
  instance:
    hostname: localhost
  client:
    service-url:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/ # 相互注册实现高可用
    register-with-eureka: false  # true 将自己注册到eureka
    fetch-registry: false
  server:
    enable-self-preservation: false
spring:
  application:
    name: eureka # 服务名称,注册之后的名称
server:
  port: 8761

　　

clienta 服务注册eureka

启动文件加入注解: 

@EnableEurekaClient

application.yml 配置文件 端口8000

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/  #,http://localhost:8762/eureka/,http://localhost:8763/eureka/
#  instance:
#    hostname: clientName
spring:
  application:
    name: clienta

@RestController
public class TestController {
    @GetMapping("/msg")
    public String msg() {
        return "this is clienta msg!!!";
    }
}

　访问  http://localhost:8000/msg     能返回结果

client 服务注册eureka 同clienta

在clien中调用clienta中方法

第一种方法:

@RestController
public class HelloController {


    @Autowired
    LoadBalancerClient loadBalancerClient;

    @GetMapping("/test")
    public String test() {
        // 获取服务实例
        ServiceInstance serviceInstance = loadBalancerClient.choose("CLIENTA");
        // 根据实例获取host port
        String host = serviceInstance.getHost();
        int port = serviceInstance.getPort();
        // 拼接url
        String url = String.format("http://%s:%s%s", host, port, "/msg");
        RestTemplate restTemplate = new RestTemplate();
        String res = restTemplate.getForObject(url, String.class);
        return res;
    }
}

　第二种: 配置config

@Component
public class RestTemplateConfig {

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

　　

@RestController
public class HelloController {

    @Autowired
    private RestTemplate restTemplate;
    @GetMapping("/test")
    public String test() {
        String res = restTemplate.getForObject("http://CLIENTA/msg", String.class);
        return res;
    }
}

　启动client 端口 8081

访问: http://localhost:8081/test

以上为基于RestTemplate 通信方式.

使用Feign通信

eureka  clienta 项目不变化
修改 client 项目:
1. 添加依赖

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

　2. 启动类添加注解

@EnableFeignClients

　3. 创建一个接口 并增加注解

@FeignClient(name = "CLIENTA")  // name是服务的名字
public interface ClientAClient {

    @GetMapping("/msg")  // 基于路由匹配, 方法名可以不同
    String msg();
}

　4. 在controller中直接使用

@RestController
public class HelloController {
    @Autowired
    private ClientAClient clientAClient;
    @GetMapping("/test")
    public String test() {
        return clientAClient.msg();
    }
}

　附pom.xml文件 注意版本对应 http://spring.io/projects/spring-cloud  官网

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>client</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>client</name>
    <description>Demo project for Spring Boot</description>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR2</spring-cloud.version>
    </properties>

    <dependencies>
        <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>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-commons</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

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


</project>