SpringBoot使用spring-boot-starter-validation实现参数校验

<!-- 如果你想显式添加 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

import javax.validation.constraints.*;

public class UserRequest {

    @NotBlank(message = "用户名不能为空")
    private String username;

    @Email(message = "邮箱格式不正确")
    private String email;

    @Min(value = 18, message = "年龄不能小于18岁")
    @Max(value = 120, message = "年龄不能大于120岁")
    private int age;

    // getters and setters...
}

@RestController
@RequestMapping("/users")
public class UserController {

    @PostMapping
    public String createUser(@Valid @RequestBody UserRequest request) {
        return "用户提交成功：" + request.toString();
    }
}

@ControllerAdvice
public class GlobalValidationHandler {

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public Map<String, String> handleValidationExceptions(MethodArgumentNotValidException ex) {
        Map<String, String> errors = new HashMap<>();
        ex.getBindingResult().getAllErrors().forEach((error) -> {
            String fieldName = ((org.springframework.validation.FieldError) error).getField();
            String errorMessage = error.getDefaultMessage();
            errors.put(fieldName, errorMessage);
        });
        return errors;
    }
}

{
  "username": "用户名不能为空",
  "email": "邮箱格式不正确"
}

public class AddressRequest {
    @NotBlank(message = "地址不能为空")
    private String detail;
    // getter/setter
}

public class UserRequest {
    @NotBlank(message = "用户名不能为空")
    private String username;

    @NotNull(message = "地址信息不能为空")
    private AddressRequest address;
    // getter/setter
}

public interface OnCreate {}
public interface OnUpdate {}

public class UserRequest {

    @NotBlank(groups = OnCreate.class, message = "创建时用户名不能为空")
    @NotBlank(groups = OnUpdate.class, message = "更新时用户名不能为空")
    private String username;

    @NotBlank(groups = OnCreate.class, message = "邮箱不能为空")
    private String email;
}

@PostMapping("/create")
public String createUser(@Validated(OnCreate.class) @RequestBody UserRequest request) {
    return "创建用户";
}

@PostMapping("/update")
public String updateUser(@Validated(OnUpdate.class) @RequestBody UserRequest request) {
    return "更新用户";
}

@Target({ ElementType.FIELD })
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = MobileValidator.class)
public @interface Mobile {
    String message() default "手机号格式不正确";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

public class MobileValidator implements ConstraintValidator<Mobile, String> {

    private static final String MOBILE_REGEX = "^1[3-9]\\d{9}$";

    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        return value != null && value.matches(MOBILE_REGEX);
    }
}

@Mobile(message = "手机号格式错误")
private String mobile;

NotBlank.userRequest.username=用户名不能为空
Mobile.userRequest.mobile=手机号格式错误