使用@ControllerAdvice统一处理参数校验的结果, 而不再使用BindingResult在Controller中处理

import lombok.extern.slf4j.Slf4j;
import org.springframework.validation.BindException;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;


@RestControllerAdvice
@Slf4j
public class ExceptionAdvice {

    @ExceptionHandler(BindException.class)
    public Object validExceptionHandler(BindException e){
        FieldError fieldError = e.getBindingResult().getFieldError();
        assert fieldError != null;
        log.error(fieldError.getField() + ":" + fieldError.getDefaultMessage());
        // 将错误的参数的详细信息封装到统一的返回实体
        ...
        return ...;
    }
}

感觉一下就方便不少,
但是, 如果你使用了@RequestBody @Valid 来封装参数并校验, 这个时候这个异常处理器又不起作用了...

{
    "timestamp": "2018-09-17T07:27:36.152+0000",
    "status": 400,
    "error": "Bad Request",
    "errors": [
        {
            "codes": [
                "NotNull.person.id",
                "NotNull.id",
                "NotNull.java.lang.Integer",
                "NotNull"
            ],
            "arguments": [
                {
                    "codes": [
                        "person.id",
                        "id"
                    ],
                    "arguments": null,
                    "defaultMessage": "id",
                    "code": "id"
                }
            ],
            "defaultMessage": "不能为null",
            "objectName": "person",
            "field": "id",
            "rejectedValue": null,
            "bindingFailure": false,
            "code": "NotNull"
        }
    ],
    "message": "Validation failed for object='person'. Error count: 1",
    "path": "/post"
}

再添加一个异常处理器, 问题解决

    @ExceptionHandler(MethodArgumentNotValidException.class)
    public Object validExceptionHandler(MethodArgumentNotValidException e){
        FieldError fieldError = e.getBindingResult().getFieldError();
        assert fieldError != null;
        log.error(fieldError.getField() + ":" + fieldError.getDefaultMessage());
        ...
        return ...;
    }

具体原因: https://jira.spring.io/browse/SPR-10157