问题一：由于马虎，缺少配置，报错如下：
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.gemantic.springcloud.service.AdditionClient': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalStateException: Method add not annotated with HTTP method type (ex. GET, POST)
Caused by: java.lang.IllegalStateException: Method add not annotated with HTTP method type (ex. GET, POST)
解决方案，在Feign接口上没有配置请求式，在接口上增加请求方式@GetMapping(value = "/add") 或 @RequestMapping(value = "/add")，完整代码如下：
@FeignClient("springcloud-addition-service")
public interface AdditionClient {
/**
* 加法接口
* @param a
* @param b
* @return
*/
// @RequestMapping(value = "/add")
@GetMapping(value = "/add")
ResponseEntity<ResultData> add(@RequestParam("a") @NotNull Integer a, @RequestParam("b") @NotNull Integer b);
}
注： value = "/add" 与真正服务一致。
问题二：
Caused by: java.lang.IllegalStateException: RequestParam.value() was empty on parameter 0
暴漏Restful服务的方法如下：
@Slf4j
@RestController
@Api(description = "加法接口")
public class AdditionController {
@Autowired
private Addition addition;
@GetMapping(value = "/add")
@ApiOperation(value = "a + b = ?")
public ResponseEntity<ResultData> add(@RequestParam @NotNull Integer a, @RequestParam @NotNull Integer b) {
if (log.isInfoEnabled()) {
log.info("add {} + {}", a, b);
}
int result = addition.add(a, b);
ResultData resultData = ResultData.builder().message(Message.builder().code(0).message(Message.SUCCESS_MESSAGE).build()).build();
resultData.setData(result);
return ResponseEntity.ok(resultData);
}
}
Feign的方式的接口如下：
@GetMapping(value = "/add")
ResponseEntity<ResultData> add(@RequestParam @NotNull Integer a, @RequestParam @NotNull Integer b);
服务启动时就会报错误：
Caused by: java.lang.IllegalStateException: RequestParam.value() was empty on parameter 0
解决方案：在@RequestParam 增加方法名
@GetMapping(value = "/add")
ResponseEntity<ResultData> add(@RequestParam("a") @NotNull Integer a, @RequestParam("b") @NotNull Integer b);
注：@PathVariable 与@ RequestParam 类似的。
问题三：
Caused by: java.lang.IllegalStateException: Method has too many Body parameters: public abstract org.springframework.http.ResponseEntity com.gemantic.springcloud.service.AdditionClient.add(java.lang.Integer,java.lang.Integer)
解决方案：当使用Feign时，如果发送的是get请求，那么需要在请求参数前加上@RequestParam 或 @PathVariable注解修饰，Controller里面可以不加该注解修饰。
@GetMapping(value = "/add")
ResponseEntity<ResultData> add(@RequestParam("a") @NotNull Integer a, @RequestParam("b") @NotNull Integer b);
