Spring boot2X Consul如何通过RestTemplate实现服务调用

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

B.使用Feign 进行声明式服务调用

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

　　http://hkgi-PC:8011 或 http://hkgi-PC:8011
　　测试地址 http://localhost:8015/hello
　　返回结果
　　hello,provider 或 hello,another provider

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

　　BestAvailableRule
　　AvailabilityFilteringRule
　　WeightedResponseTimeRule
　　RetryRule
　　RoundRobinRule
　　RandomRule
　　ZoneAvoidanceRule

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

频道导航

Spring boot2X Consul如何通过RestTemplate实现服务调用

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