统一异常处理

主要用到的注解：

@RestControllerAdvice：用于类上，标注该类作用于所有Controller

@ExceptionHandler：作用于具体方法上，标注该注解内标注异常触发的时候，执行该方法

示例：

import com.smile.dawncore.domain.AjaxResult;
import org.springframework.http.HttpStatus;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import javax.validation.ConstraintViolationException;


/**
 * 同一异常处理
 */
@RestControllerAdvice
public class CommonExceptionHandler {

    @ExceptionHandler({MethodArgumentNotValidException.class})
    @ResponseStatus(HttpStatus.OK)
    @ResponseBody
    public AjaxResult handleMethodArgumentNotValidException(MethodArgumentNotValidException ex) {
        BindingResult bindingResult = ex.getBindingResult();
        StringBuilder sb = new StringBuilder("校验失败:");
        for (FieldError fieldError : bindingResult.getFieldErrors()) {
            sb.append(fieldError.getField()).append("：").append(fieldError.getDefaultMessage()).append(", ");
        }
        String msg = sb.toString();
        return AjaxResult.error("参数校验失败:"+msg);
    }

    @ExceptionHandler({ConstraintViolationException.class})
    @ResponseStatus(HttpStatus.OK)
    @ResponseBody
    public AjaxResult handleConstraintViolationException(ConstraintViolationException ex) {
        return AjaxResult.error("参数校验失败:"+ex.getMessage());
    }

}