MyBatis-Plus 通用查询工具类

mybatis-plus简称MP是一个 Mybatis 的增强工具，在 Mybatis 的基础上只做增强不做改变，为简化开发、提高效率而生。

这是官方给的定义，关于mybatis-plus的更多介绍及特性，可以参考mybatis-plus官网 。那么它是怎么增强的呢？其实就是它已经封装好了一些crud方法，我们不需要再写xml了，直接调用这些方法就行，就类似于JPA。

下面是在MP为基础封装了一个查询类，实现了如果需要增加查询条件只需在前端修改即可。

查询工具

• SearchModel

public class SearchModel<T> {

    private Integer pageIndex;
    private Integer pageSize;
    private List<Field> fields;
    private String orderField;
    private boolean isAsc;

    public IPage<T> getPage() {
        IPage<T> page = new Page<>(pageIndex, pageSize);
        if (!StringUtil.isEmptyOrNull(orderField)) {
            OrderItem orderItem = new OrderItem();
            orderItem.setAsc(isAsc);
            orderItem.setColumn(orderField);
            page.orders().add(orderItem);
        }
        return page;

    }

    public QueryWrapper<T> getQueryModel() {
        QueryWrapper<T> queryWrapper = new QueryWrapper<>();
        for (Iterator iter = this.fields.iterator(); iter.hasNext(); ) {
            Field field = (Field) iter.next();
            switch (field.getQueryMethod()) {
                case eq:
                    queryWrapper.eq(true, field.getName(), field.getValue());
                    break;
                case like:
                    queryWrapper.like(true, field.getName(), field.getValue());
            }
        }

        if (!StringUtil.isEmptyOrNull(orderField)) {
            queryWrapper.orderBy(true, isAsc, orderField);
        }
        return queryWrapper;
    }
}

• Field

public class Field {
    public Field(String name, Object value) {
        this.name = name;
        this.value = value;
        this.queryMethod = QueryMethod.eq;
    }

    public Field(String name, Object value, QueryMethod queryMethod) {
        this.name = name;
        this.value = value;
        this.queryMethod = queryMethod;
    }

    private String name;
    private Object value;
    private QueryMethod queryMethod;
}

• QueryMethod

public enum QueryMethod {
    eq, like
}

调用示例

 {
 "fields": [
             {
             "value": "v",
             "name": "project_code",
             "queryMethod": "eq"
             },
             {
             "name": "type",
             "queryMethod": "like",
            "value": "b"
             },
             {
             "name": "id",
             "queryMethod": "like",
             "value": "a"
             }
 ],
 "pageIndex": 1,
 "pageSize": 8,
 "orderField": "type",
 "isAsc": "false"
 }

在api中传入上面的json对象即可完成一个查询服务,查询条件通过前端传入的字段控制

BaseService

• IBaseService

public interface IBaseService<T> {

    T save(T entity) throws Exception;

    boolean saveBatch(Collection<T> entityList);


    // TableId 注解存在更新记录，否插入一条记录
    boolean saveOrUpdate(T entity);

    // 根据updateWrapper尝试更新，否继续执行saveOrUpdate(T)方法
    boolean saveOrUpdate(T entity, Wrapper<T> updateWrapper);

    // 批量修改插入
    boolean saveOrUpdateBatch(Collection<T> entityList);

    // 根据 entity 条件，删除记录
    boolean remove(Wrapper<T> queryWrapper);

    // 根据 ID 删除
    boolean removeById(Serializable id);

    // 根据 columnMap 条件，删除记录
    boolean removeByMap(Map<String, Object> columnMap);

    // 删除（根据ID 批量删除）
    boolean removeByIds(Collection<? extends Serializable> idList);

    List<T> list();

    // 查询列表
    List<T> list(SearchModel<T> searchModel);

    // 查询（根据ID 批量查询）
    Collection<T> listByIds(Collection<? extends Serializable> idList);

    // 查询（根据 columnMap 条件）
    Collection<T> listByMap(Map<String, Object> columnMap);

    // 翻页查询
    IPage<T> page(SearchModel<T> searchModel);

    T selectById(Serializable id);

    T selectOne(Wrapper<T> queryWrapper);
}

• BaseServiceImpl

public class BaseServiceImpl<M extends BaseMapper<T>, T> implements IBaseService<T> {

   @Autowired
   private M baseMapper;


   @Override
   public T save(T entity) throws Exception {
       baseMapper.insert(entity);
       return entity;
   }

   @Transactional(rollbackFor = RuntimeException.class)
   @Override
   public boolean saveBatch(Collection<T> entityList) {
       Integer size = entityList.size();
       for (T entity : entityList) {
           baseMapper.insert(entity);
           size++;
       }
       return size == entityList.size();
   }

   @Override
   public boolean saveOrUpdate(T entity) {
       int rs = baseMapper.updateById(entity);
       if (rs > 0) return true;
       return baseMapper.insert(entity) > 0;
   }

   @Override
   public boolean saveOrUpdate(T entity, Wrapper<T> updateWrapper) {


       return false;
   }

   @Transactional(rollbackFor = RuntimeException.class)
   @Override
   public boolean saveOrUpdateBatch(Collection<T> entityList) {

       for (T entity : entityList) {
           saveOrUpdate(entity);
       }
       return true;
   }

   @Override
   public boolean remove(Wrapper<T> queryWrapper) {
       return baseMapper.delete(queryWrapper) > 0;
   }

   @Override
   public boolean removeById(Serializable id) {
       return baseMapper.deleteById(id) > 0;
   }

   @Override
   public boolean removeByMap(Map<String, Object> columnMap) {
       return baseMapper.deleteByMap(columnMap) > 0;
   }

   @Override
   public boolean removeByIds(Collection<? extends Serializable> idList) {
       return baseMapper.deleteBatchIds(idList) > 0;
   }

   @Override
   public List<T> list() {
       return baseMapper.selectList(new QueryWrapper<T>());
   }

   @Override
   public List<T> list(SearchModel<T> searchModel) {
       return baseMapper.selectList(searchModel.getQueryModel());
   }

   @Override
   public Collection<T> listByIds(Collection<? extends Serializable> idList) {
       return baseMapper.selectBatchIds(idList);
   }

   @Override
   public Collection<T> listByMap(Map<String, Object> columnMap) {
       return baseMapper.selectByMap(columnMap);
   }


   @Override
   public IPage<T> page(SearchModel<T> searchModel) {
       return baseMapper.selectPage(searchModel.getPage(), searchModel.getQueryModel());

   }

   @Override
   public T selectById(Serializable id) {
       return baseMapper.selectById(id);
   }

   @Override
   public T selectOne(Wrapper<T> queryWrapper) {
       return baseMapper.selectOne(queryWrapper);
   }
}

MP实现了mapper层基础的CRUD方法，这里把一些常用的service层的方法整理了一下，又减少了一些代码量

代码地址

使用示例