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@FeignClient path属性路径前缀带路径变量

路过君_P 人气:0

@FeignClient path属性路径前缀带路径变量时报错

现象

FeignClient注解中使用path属性定义url前缀时,如果使用了路径变量,则会报错

例如

@FeignClient(name = "user-api",
path = "/api/user/{id}")

报错

ERROR o.a.c.c.C.[.[localhost].[/].[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.IllegalArgumentException: Target is not a valid URI.] with root cause
java.net.URISyntaxException: Illegal character in path at index 25: http://user-api/api/user/{id}

源码分析

feign.Target

注:url成员值为@FeignClient配置的path属性值

public interface Target<T> {
    @Override
    public Request apply(RequestTemplate input) {
      if (input.url().indexOf("http") != 0) {
        input.target(url());
      }
      return input.request();
    }
}

feign.RequestTemplate

注:此处将path属性值直接解析为URI对象,如果包含形如{PathVariable}的路径变量,会导致解析异常

public final class RequestTemplate implements Serializable {
  public RequestTemplate target(String target) {
    /* target can be empty */
    if (Util.isBlank(target)) {
      return this;
    }
    /* verify that the target contains the scheme, host and port */
    if (!UriUtils.isAbsolute(target)) {
      throw new IllegalArgumentException("target values must be absolute.");
    }
    if (target.endsWith("/")) {
      target = target.substring(0, target.length() - 1);
    }
    try {
      /* parse the target */ 
      // 此处直接将path
      URI targetUri = URI.create(target);
      if (Util.isNotBlank(targetUri.getRawQuery())) {
        /*
         * target has a query string, we need to make sure that they are recorded as queries
         */
        this.extractQueryTemplates(targetUri.getRawQuery(), true);
      }
      /* strip the query string */
      this.target = targetUri.getScheme() + "://" + targetUri.getAuthority() + targetUri.getPath();
      if (targetUri.getFragment() != null) {
        this.fragment = "#" + targetUri.getFragment();
      }
    } catch (IllegalArgumentException iae) {
      /* the uri provided is not a valid one, we can't continue */
      throw new IllegalArgumentException("Target is not a valid URI.", iae);
    }
    return this;
  }
}

解决办法

如需使用路径变量使用@RequestMapping代替Path

@FeignClient(name = "user-api")
@RequestMapping("/api/user/{id}")

@FeignClient使用详解

@FeignClient标签的常用属性如下

1.首先

我们在启动类里面加入注解,声明开启Feign的远程调用,如下:

@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients
public class LoginStart {
    public static void main(String[] args) {
        SpringApplication.run(LoginStart.class, args);
    }
}

2.编写接口类

value="/xxx/xxx"就是我们服务方暴露的接口地址,如下:

import java.util.List;
import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
 
@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
    @RequestMapping(value="/custorm/getTest",method = RequestMethod.POST)
    List<String> test(@RequestParam("names") String[] names);
}

3.编写熔断类

发生错误时回调:

import java.util.List;
import org.springframework.stereotype.Component;
@Component
public class Hysitx implements IRemoteCallService{
    @Override
    public List<String> test(String[] names) {
        System.out.println("接口调用失败");
        return null;
    }
}

4.然后我们准备两个消费者工程

custorm(服务方),login(调用方),然后在login的controller中写前台调用接口:

@Autowired
private IRemoteCallService remot;
    
@RequestMapping("/config")
public String config() {
    String[] names = {"王五","张柳"};
    return remot.test(names).toString();
}

5.然后在custorm工程中写一个接口

在这个接口里我们只将传输进来的数据再添加一个数据返回回去

@RestController
@RequestMapping("/custorm")
public class CustormController {
    
    @RequestMapping("/getTest")
    public List<String> Test(String[] names) {
        List<String> name = new ArrayList<String>(Arrays.asList(names));
        name.add("王麻子");
        return name;
    }
}

6.然后我们启动注册中心

配置中心以及两个消费者服务,需要了解配置中心和注册中心的搭建可以看我前两篇文章,启动后浏览器我们进行访问

可以看到,返回的数据中已经包含了custorm工程中拼接的数据,说明我们远程调用接口成功,以上就是feign的简单使用

另外补充一些面试中长问的如何给@FeignClient添加Header信息

1.在@RequestMapping中添加,如下:

@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
	@RequestMapping(value="/custorm/getTest",method = RequestMethod.POST,
		headers = {"Content-Type=application/json;charset=UTF-8"})
    List<String> test(@RequestParam("names") String[] names);
}

2.在方法参数前面添加@RequestHeader注解,如下:

@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
	@RequestMapping(value="/custorm/getTest",method = RequestMethod.POST,
		headers = {"Content-Type=application/json;charset=UTF-8"})
    List<String> test(@RequestParam("names")@RequestHeader("Authorization") String[] names);
}

设置多个属性时,可以使用Map,如下:

import java.util.List;
import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
 
@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
	@RequestMapping(value="/custorm/getTest",method = RequestMethod.POST,
		headers = {"Content-Type=application/json;charset=UTF-8"})
    List<String> test(@RequestParam("names") String[] names, @RequestHeader MultiValueMap<String, String> headers);
}

3.使用@Header注解,如下:

@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
	@RequestMapping(value="/custorm/getTest",method = RequestMethod.POST)
	@Headers({"Content-Type: application/json;charset=UTF-8"})
    List<String> test(@RequestParam("names") String[] names);
}

4.实现RequestInterceptor接口,如下:

@Configuration
public class FeignRequestInterceptor implements RequestInterceptor {
 
    @Override
    public void apply(RequestTemplate temp) {
        temp.header(HttpHeaders.AUTHORIZATION, "XXXXX");
    }
 
}

以上为个人经验,希望能给大家一个参考,也希望大家多多支持。

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