简介
feign是声明式的web service客户端，它让微服务之间的调用变得更简单了，类似controller调用service。Spring Cloud集成了Ribbon和Eureka，可在使用Feign时提供负载均衡的http客户端。
在springcloud中不仅可以使用Ribbo进行负载均衡，也可以使用Feign。Feign是在Ribbon的基础上进行了一次改进，采用接口的方式实现负载均衡。
使用
- 导入依赖
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<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency> |
- 编写对应的接口
@FeignClient(value = "PROVIDER-NAME")声明这是一个FeignClient，value指明需要的服务id
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@FeignClient(value = "PROVIDER-NAME")public interface DeptClientService {// 请求的路径需与服务提供者的路径一致 @RequestMapping(value = "/dev/add") boolean add(Dept dept); @RequestMapping(value = "/dev/{id}") Dept queryByID(@PathVariable("id") Long id ); @PostMapping(value = "/dev/list") List<Dept> queryAll();} |
- 修改Controller
我们不再使用RestTemplate来获取所需的对象，而是通过之前定义的接口来获取
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@RestControllerpublic class ConsumerController { @Autowired private DeptClientService service; @RequestMapping("/consumer/get/{id}") public Dept getByID(@PathVariable("id") Long id){ return this.service.queryByID(id); } @RequestMapping("/consumer/add") public boolean add(String dname){ Dept dept = new Dept(); dept.setDname(dname); return this.service.add(dept); } @RequestMapping("/consumer/list") public List<Dept> list(){ return this.service.queryAll(); }} |
- 修改启动类
@EnableFeignClients 开启Feign负载均衡
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@SpringBootApplication(scanBasePackages = "com")@EnableEurekaClient@EnableFeignClients(basePackages = "com.service")public class FeignApplication { public static void main(String[] args) { SpringApplication.run(FeignApplication.class,args); }} |
- 对比:
Ribbon
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public class ConsumerController { @Autowired private RestTemplate template; private static final String url="http://PROVIDER-NAME"; @RequestMapping("/consumer/get/{id}") public Dept getByID(@PathVariable long id){ //请求的路径，返回的对象 Dept getEntity = template.getForObject(url + "/dev/" + id, Dept.class); return getEntity; } @RequestMapping("/consumer/add") public boolean add(String dname){ Dept dept = new Dept(); dept.setDname(dname); System.out.println(dept); //请求的路径，传递的参数，返回的对象 return template.postForObject(url+ "/dev/add",dept,Boolean.class); } @RequestMapping("/consumer/list") public List<Dept> list(){ //请求的路径，返回的对象 return template.postForObject(url+"/dev/list",void.class,List.class); }} |
Feign
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@RestControllerpublic class ConsumerController { @Autowired private DeptClientService service; @RequestMapping("/consumer/get/{id}") public Dept getByID(@PathVariable("id") Long id){ return this.service.queryByID(id); } @RequestMapping("/consumer/add") public boolean add(String dname){ Dept dept = new Dept(); dept.setDname(dname); return this.service.add(dept); } @RequestMapping("/consumer/list") public List<Dept> list(){ return this.service.queryAll(); }} |
总结
Feign的使用与Ribbon不同的地方在于
- Feign通过接口来实现，更符合我们的面向接口编程的习惯
- 在Ribbon的Controller中我们需要将url拼接，而Feign帮我们进行了拼接
以上就是SpringCloud Feign的使用简介的详细内容，更多关于SpringCloud Feign的资料请关注服务器之家其它相关文章！
原文链接：https://juejin.cn/post/6950254699895324679
