详解SpringBoot中@NotNull,@NotBlank注解使用

2022-08-23 14:27:13 作者：羁客%

这篇文章主要为大家详细介绍了Spring Boot中集成Validation与@NotNull,@NotBlank等注解的简单使用，感兴趣的小伙伴可以跟随小编一起学习一下

一.添加依赖

<!-- spring-boot 2.3及以上的版本只需要引入下面的依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

二.在类中使用验证注解

1.创建验证实体类（嵌套使用）

@Data
public class UserDto{
 
    @NotBlank(message = "请输入用户名称")
    private String userName;
 
    @NotBlank(message = "请正确输入密码")
    @Length(min = 6,max = 18)
    private String password;
 
    @Email(message = "请正确输入邮箱")
    private String email;
 
 
    @Valid
    @NotEmpty(message = "角色不能为空")
    private List<RoleDto> roleDtos;
 
}
//被嵌套的类
@Data
public class roleDto{
 
    @NotNull(message = "角色ID不能为空")
    private Integer roleId;
 
    @NotBlank(message = "请输入角色名称")
    private String roleName;
 
    @NotBlank(message = "请输入角色名称")
    private String roleCode;
 
    private String desc;
}

2.创建全局异常处理器，对message信息进行处理，并返回给前端

@Component
@Slf4j
public class GlobalValidHandler implements HandlerExceptionResolver {
 
    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
        ModelAndView modelAndView = new ModelAndView(new MappingJackson2JsonView());
        String errorMsg;
        if (ex instanceof BindException) {
        //对于验证注解在实体类的属性中的异常处理
            BindException bex = (BindException) ex;
            errorMsg = Objects.requireNonNull(bex.getBindingResult().getFieldError()).getDefaultMessage();
        } else if (ex instanceof ConstraintViolationException) {
        //对于验证注解直接在方法参数中使用的异常处理
            ConstraintViolationException cve = (ConstraintViolationException) ex;
            errorMsg = cve.getMessage();
            if (errorMsg != null) {
                errorMsg = errorMsg.substring(errorMsg.indexOf(": ") + 2);
            }
        } else {
        //其他
            errorMsg = ex.getMessage();
        }
        modelAndView.addObject("msg", errorMsg);
        modelAndView.addObject("code", HttpServletResponse.SC_BAD_REQUEST);
        return modelAndView;
    }
}

3.在controller中的使用

@RestController
@RequestMapping("/user")
public class UserController{
 
    @Autowired
    private UserService userService;
 
    @PostMapping("/add")
    public ApiResult addUser(@Valid @RequsetBody UserDto userDto){
        return ApiResult.data(userService.addUser(userDto));
    }
}

三.在方法参数中使用验证注解，与@RequsetParam注解同时使用，注意类上使用@Validated

@Validated
@RestController
@RequestMapping("/user")
public class UserController{
 
 @Autowired
 private UserSerivce userService;
 
 @GetMapping("/list")
 public ApiResult queryUsers(@RequestParam(name="userName", required = false, defaultValue = "")
                 @NotBlank(message = "请输入用户") String userName,
                 @RequestParam(name="pageNumber", required = false, defaultValue = 1) Integre pageNumber,
                 @RequestParam(name="pageSize", required = false, defaultValue = 10) Integre pageSize){
    return ApiResult.Data(userService.queryUsers(userName,pageNumber,pageSize));
 }
}

ps: 需要在全局变量中对验证注解进行异常处理 GlobalValidHandler

四.自定义验证注解

1.定义验证注解

@Target({ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = MyConstraintValidtor.class)
public @interface MyValidator {
 
    String message() default "校验未通过";
 
    Class<?>[] groups() default {};
 
    Class<? extends Payload>[] payload() default {};
}

2.实现验证注解的具体验证逻辑

public class MyConstraintValidator  implements ConstraintValidator<MyValidator, Object> {
    @Override
    public void initialize(MyValidator validator) {
        ConstraintValidator.super.initialize(validator);
    }
 
    @Override
    public boolean isValid(Object value, ConstraintValidatorContext context) {
        //具体校验逻辑
        //........
        //........
 
        //举个例 验证不为空
        return !ObjectUtils.isEmpty(value);
    }
}

3.使用

@Data
public class UserDto{
 
    @NotNull(message="用户名不能为空")
    private String userName;
 
    @MyValidator(message="密码不能为空")
    private String password;
}

到此这篇关于详解SpringBoot中@NotNull,@NotBlank注解使用的文章就介绍到这了,更多相关SpringBoot注解内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！