2、spring cloud服务注册中心eureka---服务消费者(第二章)-蒲公英云

服务调用

本文中示例代码的引用版本：
org.springframework.boot 版本：2.1.0.RELEASE
org.springframework.cloud 版本：Greenwich.M1
示例代码-码云 https://gitee.com/sharps/springcloud

1、pom包配置
和服务提供者一致

<?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.llx.springcloud</groupId>
    <artifactId>spring-cloud-consumer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>spring-cloud-consumer</name>
    <description>Demo spring-cloud-consumer</description>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.0.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>Greenwich.M1</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--<dependency>-->
            <!--<groupId>org.springframework.boot</groupId>-->
            <!--<artifactId>spring-boot-autoconfigure</artifactId>-->
        <!--</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>
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
</project>

2、配置文件
application.properties配置如下：

spring.application.name=spring-cloud-consumer
server.port=9091
eureka.client.serviceUrl.defaultZone=http://localhost:8888/eureka/

3、启动类
启动类添加@EnableDiscoveryClient和@EnableFeignClients注解。

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

@EnableDiscoveryClient :启用服务注册与发现
@EnableFeignClients：启用feign进行远程调用
Feign是一个声明式Web Service客户端。使用Feign能让编写Web Service客户端更加简单, 它的使用方法是定义一个接口，然后在上面添加注解，同时也支持JAX-RS标准的注解。Feign也支持可拔插式的编码器和解码器。Spring Cloud对Feign进行了封装，使其支持了Spring MVC标准注解和HttpMessageConverters。Feign可以与Eureka和Ribbon组合使用以支持负载均衡。

4、feign调用实现

@FeignClient(name= "spring-cloud-producer")
public interface HelloRemote { 
    @RequestMapping(value = "/hello")
    public String hello(@RequestParam(value = "name") String name);
}

name:远程服务名，及spring.application.name配置的名称
此类中的方法和远程服务中contoller中的方法名和参数需保持一致。

5、web层调用远程服务
将HelloRemote注入到controller层，像普通方法一样去调用即可。

@RestController
public class ConsumerController { 
    @Autowired
    HelloRemote HelloRemote;
    @RequestMapping("/hello/{name}")
    public String index(@PathVariable("name") String name) { 
        return HelloRemote.hello(name);
    }
}