<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

public class User {
  @Null
  private Long id;
  @NotBlank
  private String name;
  @Email
  private String email;
  // 省略getter和setter
}

@PostMapping("/addUser")
public String addUser(@Valid @RequestBody User user){
  ...
}

/**
 * 全局Exception處理
 *
 * @author liusq
 *
 */
@RestControllerAdvice
public class GlobalExceptionHandler {
  private static final Logger LOGGER = LoggerFactory.getLogger(GlobalExceptionHandler.class);
  @SuppressWarnings("rawtypes")
  @ExceptionHandler(value = Exception.class)
  public ResponseEntity handle(Exception e) {
    if (e instanceof MethodArgumentNotValidException) {
      BindingResult bindingResult = ((MethodArgumentNotValidException) e).getBindingResult();
      if (bindingResult.hasErrors() && bindingResult.hasFieldErrors()) {
        FieldError fieldError = bindingResult.getFieldError();
        BodyValidStatus bodyValidStatus = new BodyValidStatus.Builder().code("0009")
            .message(fieldError.getDefaultMessage())
            .field(fieldError.getField()).build();
        LOGGER.warn(bodyValidStatus.getMessage() + e);
        return new ResponseEntity<>(bodyValidStatus, HttpStatus.OK);
      } else {
        bodyStatus = DataUtil.bodyStatus("0009");
      }
    } else {
      bodyStatus = DataUtil.bodyStatus(Constants.ERROR_CODE);
    }
    LOGGER.error(bodyStatus.getMessage() + e);
    return new ResponseEntity<>(bodyStatus, HttpStatus.OK);
  }
}
public class BodyValidStatus {
  // 錯誤代碼
  private String code;
  // 錯誤代碼解釋
  private String message;
  // 錯誤字段
  private String field;
  public BodyValidStatus() {
  }
  public BodyValidStatus(String code, String message, String field) {
    this.code = code;
    this.message = message;
    this.field = field;
  }
  private BodyValidStatus(Builder builder) {
    setCode(builder.code);
    setMessage(builder.message);
    setField(builder.field);
  }
  public String getCode() {
    return code;
  }
  public void setCode(String code) {
    this.code = code;
  }
  public String getMessage() {
    return message;
  }
  public void setMessage(String message) {
    this.message = message;
  }
  public String getField() {
    return field;
  }
  public void setField(String field) {
    this.field = field;
  }
  @Override
  public String toString() {
    return ToStringBuilder.reflectionToString(this);
  }
  public static final class Builder {
    private String code;
    private String message;
    private String field;
    public Builder() {
    }
    public Builder code(String val) {
      code = val;
      return this;
    }
    public Builder message(String val) {
      message = val;
      return this;
    }
    public Builder field(String val) {
      field = val;
      return this;
    }
    public BodyValidStatus build() {
      return new BodyValidStatus(this);
    }
  }
}

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import javax.validation.Constraint;
import javax.validation.Payload;
import com.xxx.xxx.constraint.impl.MoneyValidator;
@Target({ElementType.FIELD, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy=MoneyValidator.class)
public @interface Money {
  String message() default"不是金額形式";
  Class<?>[] groups() default {};
  Class<? extends Payload>[] payload() default {};
}
import java.util.regex.Pattern;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import com.xxx.xxx.constraint.Money;
public class MoneyValidator implements ConstraintValidator<Money, Double> {
  private String moneyReg = "^\\d+(\\.\\d{1,2})?$";//表示金額的正則表達式
  private Pattern moneyPattern = Pattern.compile(moneyReg);
  public void initialize(Money money) {
    // TODO Auto-generated method stub
  }
  public boolean isValid(Double value, ConstraintValidatorContext arg1) {
    // TODO Auto-generated method stub
    if (value == null)
      return true;
    return moneyPattern.matcher(value.toString()).matches();
  }
}