java自定义注解验证实体类

1.创建一个自定义注解

/**
 * 实体检验自定义注解类
 * @author 李
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ValidateEntity {

    public boolean required() default false;//是否检验null

    public boolean requiredLeng() default false;//是否检验长度

    public int maxLength() default -1;//最大长度

    public int minLength() default -1;//最小长度

    public String errorRequiredMsg() default "";//值为null时的错误提示信息

    public String errorMinLengthMsg() default "";//最小长度不满足时的提示信息

    public String errorMaxLengthMsg() default "";//最大长度不满足时的提示信息

}

2.编写实体类验证工具类

/**
 * 验证实体工具类
 * @author 李
 */
public class ValidateEntityUtil {

    public static JsonResult validate(Object object) {
        Field[] declaredFields = object.getClass().getDeclaredFields();
        for (Field field : declaredFields) {
            ValidateEntity annotation = field.getAnnotation(ValidateEntity.class);
            if (annotation != null) {
                if (annotation.required()) {
                    //表示该字段是必填字段
                    field.setAccessible(true);
                    try {
                        Object o = field.get(object);
                        //首先判断是否为空
                        if (StringUtils.isEmpty(o)) {
                            JsonResult jsonResult = JsonResult.CUSTOM_ERROR;
                            jsonResult.setMsg(annotation.errorRequiredMsg());
                            return jsonResult;
                        }
                        //到这，说明该变量的值不是null
                        //首先判断是不是String类型
                        if (o instanceof String) {
                            //若是字符串类型，则检查其长度
                            if (annotation.requiredLeng()) {
                                if (o.toString().length() < annotation.minLength()) {
                                    JsonResult jsonResult = JsonResult.CUSTOM_ERROR;
                                    jsonResult.setMsg(annotation.errorMinLengthMsg());
                                    return jsonResult;
                                }
                                if (o.toString().length() > annotation.maxLength()) {
                                    JsonResult jsonResult = JsonResult.CUSTOM_ERROR;
                                    jsonResult.setMsg(annotation.errorMaxLengthMsg());
                                    return jsonResult;
                                }
                            }
                        }
                    } catch (IllegalArgumentException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (IllegalAccessException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }
        return JsonResult.SUCCESS;
    }

}

3.实体类使用方式

    @ValidateEntity(required = true,requiredLeng = true,errorRequiredMsg="不能为空",maxLength = 10,errorMaxLengthMsg = "超过限制10个字")
    private String content;

    private Long accountId;
    @ValidateEntity(required = true,requiredLeng = true,errorRequiredMsg="不能为空",maxLength = 30,errorMaxLengthMsg = "超过限制30个字")
    private String title;

4.编写接口测试

 @RequestMapping("test")
    JsonResult test(Problem problem){
        System.out.println(problem.getContent().length());
        System.out.println(problem.getTitle().length());
        JsonResult validate = ValidateEntityUtil.validate(problem);
        if (validate.getCode()!=1)return validate;
        return JsonResult.success(problem);
    }

5.测试