分页查询基本方式

@SpringBootTest(classes = LearningApplication.class)
public class MPTest {@AutowiredILearningLessonService lessonService;@Testpublic void test(){/*** Page<LearningLesson>：MyBatisPlus提供的分页对象* 1：当前页数* 2：每页显示的记录数*/Page<LearningLesson> page = new Page<>(1, 2);/*** wrapper：使用Lambda表达式构造的查询条件。*/LambdaQueryWrapper<LearningLesson> wrapper = new LambdaQueryWrapper<>();//用户 id 等于 2 的记录wrapper.eq(LearningLesson::getUserId, 2);//业务层的服务类调用分页查询方法   (page, wrapper) -> (分页对象，查询条件)lessonService.page(page, wrapper);}

按照某一字段升序或者降序排序

	@Testpublic void test1(){Page<LearningLesson> page = new Page<>(1, 2);/***构建按照什么字段进行排序*/List<OrderItem> itemList = new ArrayList<>();//指定排序的对象OrderItem item = new OrderItem();item.setColumn("latest_learn_time");//按什么latest_learn_time字段排序item.setAsc(false);//降序排序itemList.add(item);//排序条件添加到分页对象中page.addOrder(itemList);LambdaQueryWrapper<LearningLesson> wrapper = new LambdaQueryWrapper<>();wrapper.eq(LearningLesson::getUserId, 2);lessonService.page(page, wrapper);}

简化写法

    @Testpublic void test2(){//分页对象Page<LearningLesson> page = new Page<>(1, 2);//构建分页查询条件List<OrderItem> itemList = new ArrayList<>();OrderItem item = new OrderItem();item.setColumn("latest_learn_time");item.setAsc(false);itemList.add(item);page.addOrder(itemList);//构造查询条件和调用分页查询方法一起。lessonService.lambdaQuery().eq(LearningLesson::getUserId,2).page(page);}