公司早期后端服务（nodejs），异常返回体如下:

{
  "error_category":  string,
  "error_code": string,
  "error_message":  string,
  "error_number": number,
  "log_uuid": string
}

现在重构成 java，用的是 spring boot 。但是在异常处理这一块，要保持和之前一致。

spring 默认异常

接口定义

    @GetMapping("/params-test")
    String paramsTest(
            @Valid @Min(1)  @RequestParam("phone") String phone
    ) {
        return phone;
    }

在 postman 发起请求, 得到的响应结果如下

{
    "timestamp": "2021-07-31T14:49:49.813+00:00",
    "status": 400,
    "error": "Bad Request",
    "path": "/params-test"
}

预期的结果是

{
    "error_message": "Required request parameter 'phone' for method parameter type String is not present",
    "log_uuid": "a02ae7e7-761c-4de3-971f-0bf7df61be88",
    "error_code": "A_5",
    "error_number": 5,
    "error_category": "A"
}

如何实现预期结果

1. 定义一个异常处理类，并加上注解ControllerAdvice，当程序抛出异常时，就会执行 handleServletRequestBindingException，这时我们就可以定制化的输出异常信息了。

@ControllerAdvice
public class ApiExceptionHandler {

    @ExceptionHandler({ MissingServletRequestParameterException.class })
    public ResponseEntity<HashMap<String, Object>> handleServletRequestBindingException(MissingServletRequestParameterException ex, HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) {
        HashMap<String, Object> stringObjectHashMap = new HashMap<>();
        stringObjectHashMap.put("error_code", "A_5");
        stringObjectHashMap.put("error_category", "A");
        stringObjectHashMap.put("error_number", 5);
        stringObjectHashMap.put("error_message", ex.getMessage());
        stringObjectHashMap.put("log_uuid", UUID.randomUUID().toString());
        return new ResponseEntity<>(stringObjectHashMap, HttpStatus.BAD_REQUEST);
    }

   // 当然这里肯定还需要处理其他异常的
}

2. 另外一种写法, 继承 ResponseEntityExceptionHandler, 并重写异常处理方法

@ControllerAdvice
public class ApiExceptionHandler extends ResponseEntityExceptionHandler {
   
   @Override
   protected ResponseEntity<Object> handleMissingServletRequestParameter(MissingServletRequestParameterException ex, HttpHeaders headers, HttpStatus status, WebRequest request) {
       HashMap<String, Object> stringObjectHashMap = new HashMap<>();
       stringObjectHashMap.put("error_code", "A_5");
       stringObjectHashMap.put("error_category", "A");
       stringObjectHashMap.put("error_number", 5);
       stringObjectHashMap.put("error_message", ex.getMessage());
       stringObjectHashMap.put("log_uuid", UUID.randomUUID().toString());
       return this.handleExceptionInternal(ex, stringObjectHashMap, headers, status, request);
   }

   // 建议这里复写其他异常处理方法，保持错误信息输出结构一致
}