MyBatis-Plus之基础CURD

基础方法

MP提供了一些基础好用的方法，直接开箱即用。下面做简单的演示.
这里注意，我展示的是Service层的公共方法，Dao层的有时间我会另开一篇进行解析.

getById 根据ID查询数据

    @Override
    public ActivityEntity getDataById() {
        // 从数据库中复制的id，测试使用
        Long id = 1293926691101519873L;
        ActivityEntity activityEntity = getById(id);
        return activityEntity;
    }

控制台打印结果:

image.png

listByIds 根据ID列表查询数据

这其实就是一个in()查询

        List<Long> ids = Arrays.asList(1293926691101519873L, 1293926692372393985L, 1293926692380782593L, 1293926692380782594L);
        List<ActivityEntity> activityEntityList = listByIds(ids);
        return activityEntityList;

控制台打印结果:

image.png

listByMap 根据Map构建查询条件进行查询

这是一个使用Map作为参数的查询方法。注意这里的Map参数为:
KEY: 数据库的column
VALUE: 相等的值

这里我查询的是活动名称等于13号的活动,报名人数为5的活动列表信息

        HashMap<String, Object> paramsMap = new HashMap<>(4);
        paramsMap.put("activity_name", "13号的活动");
        paramsMap.put("count", 5);
        List<ActivityEntity> activityEntityList = listByMap(paramsMap);
        return activityEntityList;

控制台打印结果:

image.png

save 保存数据

        ActivityEntity activityEntity = new ActivityEntity();
        activityEntity.setActivityId(2L);
        activityEntity.setActivityName("企业级活动");
        activityEntity.setActivityType(1);
        activityEntity.setCount(5);
        activityEntity.setCreateTime(new Date());
        save(activityEntity);

控制台打印效果:

image.png

saveBatch 批量插入数据

        Date create_time = new Date();
        ActivityEntity activityEntity = ActivityEntity.getInstance(2L, "企业级活动", 0, 5, create_time);
        ActivityEntity activityEntity1 = ActivityEntity.getInstance(2L, "企业级活动", 1, 10, create_time);
        ActivityEntity activityEntity2 = ActivityEntity.getInstance(2L, "企业级活动", 1, 12, create_time);
        ActivityEntity activityEntity3 = ActivityEntity.getInstance(2L, "企业级活动", 2, 2, create_time);
        ActivityEntity activityEntity4 = ActivityEntity.getInstance(2L, "企业级活动", 2, 3, create_time);
        ActivityEntity activityEntity5 = ActivityEntity.getInstance(2L, "企业级活动", 0, 8, create_time);
        ActivityEntity activityEntity6 = ActivityEntity.getInstance(2L, "企业级活动", 0, 22, create_time);
        List<ActivityEntity> activityEntityList = Arrays.asList(activityEntity, activityEntity1, activityEntity2, activityEntity3, activityEntity4, activityEntity5, activityEntity6);
        saveBatch(activityEntityList);

控制台打印效果:

image.png

updateById 根据主键更新数据

        ActivityEntity data = getById(1293926691101519873L);
        data.setActivityName("活动变更");
        updateById(data);

控制台打印效果:

image.png

updateBatchById 批量更新数据

        // 这里复用了批量查询。读者可以自行构造数据
        List<ActivityEntity> dataList = getDataList();
        dataList.forEach(activityEntity -> activityEntity.setCreateTime(new Date()));
        updateBatchById(dataList);

控制台打印效果:

image.png

removeById 根据ID删除数据

       removeById(1297437208340402178L);

控制台打印效果:

image.png

removeByIds 根据ID列表批量删除数据

        List<Long> ids = Arrays.asList(1297437208340402177L, 1297437208332013572L, 1297437208332013571L);
        removeByIds(ids);

控制台打印效果:

image.png