传入对象进行多条件查询——by QueryWrapper && 反射

@Data
public class SearchServerDto implements Serializable {

    private Long serverid;

    private String host;

    private String nickname;

    private Date createtime;
}

若前端传入该对象，想通过该对象进行搜索按条件搜索
如果采用传统的方法，进行每一个属性都进行判断则需要很多的if else if
但如果采用反射和注解的思想将减少繁琐的步骤，且具有通用性
分析：
作者使用的是Mybatis-X生成的实体类
有注解@TableId、@TableField，故新添了一个注解来做分辨

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface FieldAnnoation {
    String Annoationtype() default "TableField";
}

可以使用反射，动态的将SearchServerDto注入到QueryWrapper 中

  QueryWrapper<UserServer> queryWrapper = new QueryWrapper<>();
        UserServer userServer = new UserServer();
        List<UserServer> list;
        if (ObjectUtils.isEmpty(searchServerDto)){
             list = userServerService.list();


        }else{
            Class<? extends SearchServerDto> searchServerDtoClass = searchServerDto.getClass();
            Class<? extends UserServer> userServerClass = userServer.getClass();
            
            Field[] fields = userServerClass.getDeclaredFields();//获取实体类字节码对象的private属性
            for (Field f:fields
                 ) {
                FieldAnnoation fieldAnnoation = f.getAnnotation(FieldAnnoation.class);//获取属性上的自定义注解
                if (!ObjectUtils.isEmpty(fieldAnnoation)){
                    String annoationtype = fieldAnnoation.Annoationtype();
                    if (annoationtype.equals("TableField")){//判断该注解的类型
                        TableField tableField = f.getAnnotation(TableField.class);//获取TableField注解上的数据库表的名称
                        Field declaredField = searchServerDtoClass.getDeclaredField(f.getName());//获取searchServerDto的属性
                        declaredField.setAccessible(true);//设置可访问该属性
                        Object o = declaredField.get(searchServerDto);//获取searchServerDto对象的属性值
                        if (!ObjectUtils.isEmpty(o)){
                            queryWrapper.eq(tableField.value(),o);
                        }
                    }else{
                        TableId tableId = f.getAnnotation(TableId.class);
                        Field field = searchServerDtoClass.getDeclaredField(f.getName());
                        field.setAccessible(true);
                        Object o = field.get(searchServerDto);
                        if (!ObjectUtils.isEmpty(o)){
                            queryWrapper.eq(tableId.value(),o);
                        }

                    }
                }

            }


            list = userServerService.list(queryWrapper);


        }
        return Result.success(list);