feigin使用需要注意的一些问题

1、feigin无法多继承只允许单继承接口如需要解决代码冗余只能单继承所以尽量继承接口多的那个接口

public interface SlideshowtimeInterface {

    @RequestMapping(value = "/slideshowtime/updateTime", method = RequestMethod.POST)
    public Map<String, Object> updatetime(@RequestBody(required = false)String json)throws UnsupportedEncodingException;

    @RequestMapping(value = "/slideshowtime/loadtime", method = RequestMethod.POST)
    public Map<String, Object> loadtime(@RequestBody(required = false)String json)throws UnsupportedEncodingException;
}


public interface PictureInterface {

    @RequestMapping(value = "/picture/initializeAdPosition", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
    public Map<String,Object> initializeAdPosition(@RequestBody(required = false)String json);

    @RequestMapping(value = "/picture/saveOrUpdate", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
    public Map<String,Object> save(@RequestBody(required = false)String json);

    @RequestMapping(value = "/picture/load", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
    public Map<String, Object> load(@RequestBody( required = false)String json);

    @RequestMapping(value = "/picture/queryBannerOfproduct", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
    public Map<String, Object> queryBannerOfproduct(@RequestBody( required = false)String json);

    @RequestMapping(value = "/picture/queryBannerOfproducts", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
    public Map<String, Object> queryBannerOfproducts(@RequestBody( required = false)String json);

    @RequestMapping(value = "/picture/move", method = {RequestMethod.POST})
    public Map<String, Object> move(@RequestBody(required = false)String json);

    @RequestMapping(value = "/picture/delete", method = RequestMethod.POST)
    public Map<String, Object> delete(@RequestBody(required = false)String json);

    @RequestMapping(value = "/picture/isEffect", method = RequestMethod.POST)
    public Map<String, Object> isEffect(@RequestBody(required = false)String json);
}

错误写法

调用方书写
@FeignClient(value = "djslideshow-server",path = "/djslideshowserver" )
public interface FeiginClient extends PictureInterface,SlideshowtimeInterface{

}

Caused by: java.lang.IllegalStateException: Only single inheritance supported: PayfeiginClient

正确写法

调用方书写
@FeignClient(value = "djslideshow-server",path = "/djslideshowserver" )
public interface FeiginClient extends PictureInterface {

 @RequestMapping(value = "/slideshowtime/updateTime", method = RequestMethod.POST)
    public Map<String, Object> updatetime(@RequestBody(required = false)String json)throws UnsupportedEncodingException;

    @RequestMapping(value = "/slideshowtime/loadtime", method = RequestMethod.POST)
    public Map<String, Object> loadtime(@RequestBody(required = false)String json)throws UnsupportedEncodingException;

}

为什么？

原因在于接口是可以对接口进行继承的但是spring对于使用@feiginClient 注解修饰的接口会对其进行实现并注入bean 其就相当于是一个类类是不允许多继承的

而且不建议继承这种服务器端和客户端之间共享接口方式，因为这种方式会造成服务器端和客户端代码的紧耦合。并且，Feign本身并不使用Spring MVC的工作机制（方法参数映射不被继承）

2、feigin调用的请求类型以及参数。

当参数比较复杂时，feign即使声明为get请求也会强行使用post请求
不支持@GetMapping类似注解声明请求，需使用@RequestMapping(value = “url”,method = RequestMethod.GET)
使用@RequestParam注解时必须要在后面加上参数名
1. TbItem对象，使用@RequestBody来声明
2. String字符串，使用@RequestParam(“xxx”)来声明

@PostMapping(value = "bankCard/judgeCardFroPreNumber")
	public  HttpResult<?> judgeCardPreNumber(@RequestParam(value = "faccountNumber") String faccountNumber);

如果不加则报错

feign.FeignException: status 500 reading PayfeiginClient#judgeCardPreNumber(String)

3、feigin调用的方法最好不要有多实体参数因为不支持如果一定需要你要对方法进行重写编码器修饰包装

SpringCloud Feign重写编码器支持pojos多实体与文件数组参数传递的方法请看博客 :https://blog.csdn.net/qq_34523427/article/details/88863800

4、feigin的调用方与被调用方都必须在同一个注册中心并且被调用方一定要先启动当然后启动也行不过需要等待30秒eureka 注册中心对被调用服务进行心跳机制判断

feigin的实现就是依靠eureka的所以不用说了

5、一个项目里面准确的说时一个服务里面不允许两个feigin客户端代理同一个服务即使feigin名称不一致

@FeignClient(value = "pay-server/djpay")
public interface PaybankFeiginClient extends BalanceModuleInterface {
}

@FeignClient(name = "pay-server/djpay")
public interface PayfeiginClient extends BankCardModuleInterface {

当实现feigin时会出现以下错误：
The bean ‘pay-server/djpay.FeignClientSpecification’, defined in null, could not be registered. A bean with that name has already been defined in null and overriding is disabled.

无法注册以null定义的bean“pay-server / djpay.FeignClientSpecification”。具有该名称的bean已在null中定义，并且已禁用覆盖。