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
