mybatis-plus简称MP是一个 Mybatis 的加强工具，在 Mybatis 的根底上只做加强不做扭转，为简化开发、提高效率而生。

这是官网给的定义，对于mybatis-plus的更多介绍及个性，能够参考mybatis-plus官网 。那么它是怎么加强的呢？其实就是它曾经封装好了一些crud办法，咱们不须要再写xml了，间接调用这些办法就行，就相似于JPA。

上面是在MP为根底封装了一个查问类，实现了如果须要减少查问条件只需在前端批改即可。

查问工具

• 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中传入下面的json对象即可实现一个查问服务,查问条件通过前端传入的字段管制

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);    // 依据updateWrapper尝试更新，否继续执行saveOrUpdate(T)办法    boolean saveOrUpdate(T entity, Wrapper<T> updateWrapper);    // 批量批改插入    boolean saveOrUpdateBatch(Collection<T> entityList);    // 依据 entity 条件，删除记录    boolean remove(Wrapper<T> queryWrapper);    // 依据 ID 删除    boolean removeById(Serializable id);    // 依据 columnMap 条件，删除记录    boolean removeByMap(Map<String, Object> columnMap);    // 删除（依据ID 批量删除）    boolean removeByIds(Collection<? extends Serializable> idList);    List<T> list();    // 查问列表    List<T> list(SearchModel<T> searchModel);    // 查问（依据ID 批量查问）    Collection<T> listByIds(Collection<? extends Serializable> idList);    // 查问（依据 columnMap 条件）    Collection<T> listByMap(Map<String, Object> columnMap);    // 翻页查问    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层根底的CRUD办法，这里把一些罕用的service层的办法整顿了一下，又缩小了一些代码量

代码地址

应用示例