Java中Spring Cloud如何实现服务发现与负载均衡

在Spring Cloud中，服务发现通常是通过Spring Cloud Netflix的Eureka客户端实现的，负载均衡则可以通过Ribbon来实现。以下是一个简单的例子：

1. 添加依赖到你的pom.xml：

<dependencies>
    <!-- Eureka Discovery Client -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <!-- Ribbon -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
    </dependency>
</dependencies>
 
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>版本号</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

2. 配置application.properties或application.yml：

spring:
  application:
    name: service-ribbon
server:
  port: 8080
 
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

3. 启动类添加@EnableDiscoveryClient注解：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
 
@SpringBootApplication
@EnableDiscoveryClient
public class ServiceRibbonApplication {
 
    @Bean
    @LoadBalanced
    RestTemplate restTemplate() {
        return new RestTemplate();
    }
 
    public static void main(String[] args) {
        SpringApplication.run(ServiceRibbonApplication.class, args);
    }
}

4. 使用RestTemplate进行服务调用：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
 
@RestController
public class HelloController {
 
    private final RestTemplate restTemplate;
 
    @Autowired
    public HelloController(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;