SpringCloud之服务提供与调用
SpringCloud之服务提供与调用
上一篇文章我们介绍了eureka服务注册中心的搭建,这篇文章介绍一下如何使用eureka服务注册中心,搭建一个
简单的服务端注册服务,客户端去调用服务使用的案例。
案例中有三个角色:服务注册中心、服务提供者、服务消费者,其中服务注册中心就是我们上一篇的eureka单机
版启动既可,流程是首先启动注册中心,服务提供者生产服务并注册到服务中心中,消费者从服务中心中获取服务
并执行。
1、服务注册中心
1.1 pom依赖
<?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 https://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>1.5.3.RELEASE</version><relativePath/></parent><groupId>com.example</groupId><artifactId>spring-cloud-eureka</artifactId><version>0.0.1-SNAPSHOT</version><name>spring-cloud-eureka</name><description>SpringCloud服务注册中心</description><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>Dalston.RELEASE</spring-cloud.version></properties><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka-server</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>
1.2 配置文件
spring.application.name=spring-cloud-eureka
server.port=8000
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/
1.3 启动类
package com.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;@SpringBootApplication
@EnableEurekaServer
public class SpringCloudEurekaApplication {public static void main(String[] args) {SpringApplication.run(SpringCloudEurekaApplication.class, args);}}
访问http://localhost:8000/:

2、服务提供
我们假设服务提供者有一个hello方法,可以根据传入的参数,提供输出“hello xxx,this is first messge”的服务。
2.1 pom包配置
创建一个springboot项目,pom.xml中添加如下配置:
<?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 https://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>1.5.3.RELEASE</version><relativePath/></parent><groupId>com.example</groupId><artifactId>spring-cloud-producer</artifactId><version>0.0.1-SNAPSHOT</version><name>spring-cloud-producer</name><description>SpringCloud服务提供</description><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>Dalston.RELEASE</spring-cloud.version></properties><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</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>
2.2 配置文件
application.properties配置如下:
spring.application.name=spring-cloud-producer
server.port=9000
eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/
2.3 启动类
启动类中添加@EnableDiscoveryClient注解
package com.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;@SpringBootApplication
@EnableDiscoveryClient
public class SpringCloudProducerApplication {public static void main(String[] args) {SpringApplication.run(SpringCloudProducerApplication.class, args);}}
2.4 controller
提供hello服务
package com.example.controller;import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;@RestController
public class HelloController {@RequestMapping("/hello")public String index(@RequestParam String name) {return "hello "+name+",this is first messge";}
}
添加@EnableDiscoveryClient注解后,项目就具有了服务注册的功能。启动工程后,就可以在注册中心的页面
看到SPRING-CLOUD-PRODUCER服务。

到此服务提供者配置就完成了。
3、服务调用
3.1 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 https://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>1.5.3.RELEASE</version><relativePath/></parent><groupId>com.example</groupId><artifactId>spring-cloud-consumer</artifactId><version>0.0.1-SNAPSHOT</version><name>spring-cloud-consumer</name><description>SpringCloud服务调用</description><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>Dalston.RELEASE</spring-cloud.version></properties><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-feign</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</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>
3.2 配置文件
application.properties配置如下:
spring.application.name=spring-cloud-consumer
server.port=9001
eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/
3.3 启动类
启动类添加@EnableDiscoveryClient和@EnableFeignClients注解。
package com.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class SpringCloudConsumerApplication {public static void main(String[] args) {SpringApplication.run(SpringCloudConsumerApplication.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。
3.4 feign调用实现
package com.example.remote;import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;@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。
3.5 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。
package com.example.controller;import com.example.remote.HelloRemote;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class ConsumerController {@AutowiredHelloRemote helloRemote;@RequestMapping("/hello/{name}")public String index(@PathVariable("name") String name) {return helloRemote.hello(name);}}
到此,最简单的一个服务注册与调用的例子就完成了。
4、测试
4.1 简单调用
依次启动spring-cloud-eureka、spring-cloud-producer、spring-cloud-consumer三个项目:

先输入:http://localhost:9000/hello?name=neo 检查spring-cloud-producer服务是否正常
返回:hello neo,this is first messge

说明spring-cloud-producer正常启动,提供的服务也正常。
浏览器中输入:http://localhost:9001/hello/neo
返回:hello neo,this is first messge

说明客户端已经成功的通过feign调用了远程服务hello,并且将结果返回到了浏览器。
4.2 负载均衡
新建一个服务提供者和上面新建的一样。
pom依赖
<?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 https://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>1.5.3.RELEASE</version><relativePath/></parent><groupId>com.example</groupId><artifactId>spring-cloud-producer2</artifactId><version>0.0.1-SNAPSHOT</version><name>spring-cloud-producer2</name><description>Demo project for Spring Boot</description><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>Dalston.RELEASE</spring-cloud.version></properties><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</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>
在配置文件中改动端口:
spring.application.name=spring-cloud-producer
server.port=9002
eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/
以上面spring-cloud-producer为例子修改,将其中的controller改动如下:
package com.example.controller;import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;@RestController
public class HelloController {@RequestMapping("/hello")public String index(@RequestParam String name) {return "hello "+name+",this is producer 2 send first messge";}
}
启动类:
package com.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;@SpringBootApplication
@EnableDiscoveryClient
public class SpringCloudProducer2Application {public static void main(String[] args) {SpringApplication.run(SpringCloudProducer2Application.class, args);}}
打包启动后,在eureka就会发现两个服务提供者,如下图:

然后在浏览器再次输入:http://localhost:9001/hello/neo 进行测试:
第一次返回结果:hello neo,this is first messge
第二次返回结果:hello neo,this is producer 2 send first messge


不断的进行测试下去会发现两种结果交替出现,说明两个服务中心自动提供了服务均衡负载的功能。如果我们将服
务提供者的数量在提高为N个,测试结果一样,请求会自动轮询到每个服务端来处理。
