这篇文章主要介绍了spring boot2X Consul如何通过RestTemplate实现服务调用,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下
Consul可以用于实现分布式系统的服务发现与配置
服务调用有两种方式：
A.使用RestTemplate 进行服务调用
负载均衡——通过Ribbon注解RestTemplate
负载均衡——默认使用Ribbon实现
先使用RestTemplate来实现
1.服务注册发现中心
启动Consul
consul agent -dev
2.服务端
在spring boot2X整合Consul 的基础上
添加服务provider，provider1
provider测试方法
package com.xyz.provider.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class demoController {
@RequestMapping("/hello")
public String Hello(){
return "hello,provider";
}
}
provider1测试方法
package com.xyz.provider1.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class demoController {
@RequestMapping("/hello")
public String Hello(){
return "hello,another provider";
}
}
启动provider和provider1
浏览器访问http://localhost:8500
有两个服务提供者节点实例
3.客户端
（1）添加依赖
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.SR4</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-consul-discovery</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>
（2）添加配置
server.port=8015 spring.application.name=xyz-comsumer spring.cloud.consul.host=localhost spring.cloud.consul.port=8500 spring.cloud.consul.discovery.register=false spring.cloud.consul.discovery.health-check-url=/actuator/health spring.cloud.consul.discovery.heartbeat.enabled=true management.endpoints.web.exposure.include=* management.endpoint.health.show-details=always
（3）测试方法
获取所有注册的服务，从注册的服务中选取一个，服务调用
package com.xyz.comsumer.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class HelloController {
@Autowired
private LoadBalancerClient loadBalancer;
@Autowired
private DiscoveryClient discoveryClient;
private String serviceName = "service-provider";
@RequestMapping("/services")
public Object services() {
return discoveryClient.getInstances(serviceName);
}
@RequestMapping("/discover")
public Object discover() {
return loadBalancer.choose(serviceName).getUri().toString();
}
@RequestMapping("/hello")
public String hello() {
ServiceInstance serviceInstance = loadBalancer.choose(serviceName);
String callServiceResult = new RestTemplate().getForObject(serviceInstance.getUri().toString() + "/hello", String.class);
return callServiceResult;
}
}
注：
客户端调用的服务名，是在服务端指定的，在服务端配置里使用 spring.cloud.consul.discovery.service-name指注册到 Consul 的服务名称
测试
启动Consul
启动provider和provider1
启动comsumer
测试地址 http://localhost:8015/services
返回结果
[
{
"instanceId": "provider-8010",
"serviceId": "service-provider",
"host": "hkgi-PC",
"port": 8010,
"secure": false,
"metadata": {
"secure": "false"
},
"uri": "http://hkgi-PC:8010",
"scheme": null
},
{
"instanceId": "provider-8011",
"serviceId": "service-provider",
"host": "hkgi-PC",
"port": 8011,
"secure": false,
"metadata": {
"secure": "false"
},
"uri": "http://hkgi-PC:8011",
"scheme": null
}
]
测试地址 http://localhost:8015/discover
返回结果
注：
结果交替出现的，这是因为负载均衡器是采用的是轮询的方式
说明：
调用的过程：
A.通过LoadBalancerClient查询服务
B.通过RestTemplate调用远程服务
Ribbon负载均衡策略
自定义Ribbon负载均衡——使用随机访问策略
修改启动类
package com.xyz.comsumer;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
public class ComsumerApplication {
public static void main(String[] args) {
SpringApplication.run(ComsumerApplication.class, args);
}
@Bean
@LoadBalanced
public RestTemplate restTemplate(){
return new RestTemplate();
}
}
服务调用
package com.xyz.comsumer.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class RibbonHelloController {
@Autowired
private RestTemplate restTemplate;
private String serviceName = "service-provider";
@RequestMapping("/ribbon/hello")
public String hello() {
String callServiceResult = restTemplate.getForObject("http://"+serviceName+"/hello", String.class);
return callServiceResult;
}
}
配置添加
service-provider.ribbon.NFLoadBalancerRuleClassName=com.netflix.loadbalancer.RandomRule
重新启动 comsumer
测试地址 http://localhost:8015/ribbon/hello
输出的结果不再是交替出现，改为随机的了
