Spring Cloud 服务发布与调用

1. 引入相关依赖pom.xml

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.zws.cloud</groupId>
    <artifactId>Eurka-Producer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Eurka-Producer</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- Eureka 客户端依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
    </dependencies>

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

</project>

2. 配置Eureka Server地址 application.yml

server:
  port: 8080

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

spring:
  application:
    name: Eureka-Producer

3. 发布一个服务，其实就是一个Http接口，如下：

package com.zws.cloud.producer;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @Author wensh.zhu
 * @Date 2019/2/16 19:33
 */
@RestController
public class HelloController {

    @GetMapping("/hello")
    public String hello() {
        return "hello";
    }
}

启动 
package com.zws.cloud.producer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class EurekaProducerApplication {

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

}

2. 调用服务

1. 依赖配置pom.xml

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.zws.cloud</groupId>
    <artifactId>Eurka-Producer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Eurka-Producer</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <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>

        <!-- Ribbon用于客户端负载均衡 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

        <!-- Feign用于服务发现与调用 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

    </dependencies>

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

</project>

2. 启用Ribbon负载均衡以及Feign接口注入，application.yml

server:
  port: 8088

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

spring:
  application:
    name: Eureka-Consumer

3. 定义Feign客户端以及熔断回调

package com.zws.cloud.consumer;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

/**
 * @Author wensh.zhu
 * @Date 2019/2/16 15:14
 */
@FeignClient(value = "Eureka-Producer", fallbackFactory = HelloClientFallbackFactory.class)
public interface HelloClient {

    @GetMapping("/hello")
    String hello();
}

package com.zws.cloud.consumer;

import feign.hystrix.FallbackFactory;
import org.springframework.stereotype.Component;

/**
 * @Author wensh.zhu
 * @Date 2019/2/16 16:12
 */
@Component
public class HelloClientFallbackFactory implements FallbackFactory<String>, HelloClient {
    @Override
    public String create(Throwable throwable) {
        return this.hello();
    }

    @Override
    public String hello() {
        return "";
    }
}

@FeignClient(value = "Eureka-Producer", fallbackFactory = HelloClientFallbackFactory.class)其中Eurka-Producer为服务提供方的实例名称（spring.application.name）

4. 启用Feign接口以及调用

package com.zws.cloud.EurkaProducer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@RestController
@EnableFeignClients
@SpringBootApplication
public class EurkaProducerApplication {

    @Resource
    private HelloFeign helloFeign;

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

    @GetMapping("/hello")
    public String hello() {
        return helloFeign.hello();
    }

}

3. 总结

服务发布主要涉及如下三个方面：

1. 配置Eureka Server地址：

   ## 多个以逗号隔开
   eureka:
   client:
   serviceUrl:
     defaultZone: http://peer1:8761/eureka/

2. 引入Eureka Client依赖

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

3. 定义普通的Http接口

服务调用：

1. 引入三个依赖：

<!-- Eureka客户端 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

<!-- Ribbon用于负载均衡 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>

<!-- Feign用于服务发布与调用 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

2. 配置Eureka Server：

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8762/eureka/

3. 定义FeignClient接口以及失败的回调
4. 启动类添加@EnableFeignClients注解

@EnableFeignClients会把第三步定义的接口注入Spring上下文中 ，然后使用的时候直接注入即可。

Spring Cloud 服务发布与调用

原文：http://blog.51cto.com/wenshengzhu/2350974