这个依赖不存在 <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-etcd</artifactId> <version>3.0.1</version></dependency>

非常抱歉，我犯了一个错误。目前Spring Cloud Etcd Starter的最新版本是2.2.4.RELEASE。以下是正确的依赖：

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-etcd</artifactId>
    <version>2.2.4.RELEASE</version>
</dependency>

同时，我也注意到在上一个回答中缺少一些必要的配置。下面是完整的示例代码：

在pom.xml中添加以下依赖：

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-etcd</artifactId>
    <version>2.2.4.RELEASE</version>
</dependency>

在application.yml中添加ETCD的配置：

spring:
  cloud:
    etcd:
      endpoints: http://localhost:2379

在Service中注入EtcdKeyValueRepository并进行操作：

import org.springframework.cloud.etcd.config.EtcdKeyValueRepository;
import org.springframework.stereotype.Service;

@Service
public class EtcdService {

    private final EtcdKeyValueRepository etcdKeyValueRepository;

    public EtcdService(EtcdKeyValueRepository etcdKeyValueRepository) {
        this.etcdKeyValueRepository = etcdKeyValueRepository;
    }

    public void save(String key, String value) {
        etcdKeyValueRepository.put(key, value);
    }

    public String get(String key) {
        return etcdKeyValueRepository.get(key);
    }

    public void delete(String key) {
        etcdKeyValueRepository.delete(key);
    }
}

在Controller中调用EtcdService来操作ETCD：

import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/etcd")
public class EtcdController {

    private final EtcdService etcdService;

    public EtcdController(EtcdService etcdService) {
        this.etcdService = etcdService;
    }

    @PostMapping("/{key}/{value}")
    public void save(@PathVariable String key, @PathVariable String value) {
        etcdService.save(key, value);
    }

    @GetMapping("/{key}")
    public String get(@PathVariable String key) {
        return etcdService.get(key);
    }

    @DeleteMapping("/{key}")
    public void delete(@PathVariable String key) {
        etcdService.delete(key);
    }

}

希望这次回答能够帮到你，如有其他问题，请随时提出。