ServiceImpl类是我们进行SQL操作中非常重要的一个类，通过MyBatisPlus生成的各个实体类的XXXImpl都会继承ServiceImpl类那里继承全部的方法，那么ServiceImpl类中有哪些方法呢？如下介绍：
/** * IService 实现类（ 泛型：M 是 mApper 对象，T 是实体 ） * * @author hubin * @since 2018-06-23 */@SuppressWarnings("unchecked")public class ServiceImpl<M extends BaseMapper<T>, T> implements IService<T> { protected Log log = LogFactory.getLog(getClass()); @Autowired protected M baseMapper; @Override public M getBaseMapper() { return baseMapper; } protected Class<T> entityClass = currentModelClass(); @Override public Class<T> getEntityClass() { return entityClass; } protected Class<T> mapperClass = currentMapperClass(); /** * 判断数据库操作是否成功 * * @param result 数据库操作返回影响条数 * @return boolean * @deprecated 3.3.1 */ @Deprecated protected boolean retBool(Integer result) { return SqlHelper.retBool(result); } protected Class<T> currentMapperClass() { return (Class<T>) ReflectionKit.getSuperClassGenericType(getClass(), 0); } protected Class<T> currentModelClass() { return (Class<T>) ReflectionKit.getSuperClassGenericType(getClass(), 1); } /** * 批量操作 SqlSession * * @deprecated 3.3.0 */ @Deprecated protected SqlSession sqlSessionBatch() { return SqlHelper.sqlSessionBatch(entityClass); } /** * 释放sqlSession * * @param sqlSession session * @deprecated 3.3.0 */ @Deprecated protected void closeSqlSession(SqlSession sqlSession) { SqlSessionUtils.closeSqlSession(sqlSession, GlobalConfigUtils.currentSessionFactory(entityClass)); } /** * 获取 SqlStatement * * @param sqlMethod ignore * @return ignore * @see #getSqlStatement(SqlMethod) * @deprecated 3.4.0 */ @Deprecated protected String sqlStatement(SqlMethod sqlMethod) { return SqlHelper.table(entityClass).getSqlStatement(sqlMethod.getMethod()); } /** * 批量插入 * * @param entityList ignore * @param batchSize ignore * @return ignore */ @Transactional(rollbackFor = Exception.class) @Override public boolean saveBatch(Collection<T> entityList, int batchSize) { String sqlStatement = getSqlStatement(SqlMethod.INSERT_ONE); return executeBatch(entityList, batchSize, (sqlSession, entity) -> sqlSession.insert(sqlStatement, entity)); } /** * 获取mapperStatementId * * @param sqlMethod 方法名 * @return 命名id * @since 3.4.0 */ protected String getSqlStatement(SqlMethod sqlMethod) { return SqlHelper.getSqlStatement(mapperClass, sqlMethod); } /** * TableId 注解存在更新记录，否插入一条记录 * * @param entity 实体对象 * @return boolean */ @Transactional(rollbackFor = Exception.class) @Override public boolean saveOrUpdate(T entity) { if (null != entity) { TableInfo tableInfo = TableInfoHelper.getTableInfo(this.entityClass); Assert.notNull(tableInfo, "error: can not execute. because can not find cache of TableInfo for entity!"); String keyProperty = tableInfo.getKeyProperty(); Assert.notEmpty(keyProperty, "error: can not execute. because can not find column for id from entity!"); Object idVal = ReflectionKit.getFieldValue(entity, tableInfo.getKeyProperty()); return StringUtils.checkValNull(idVal) || Objects.isNull(getById((Serializable) idVal)) ? save(entity) : updateById(entity); } return false; } @Transactional(rollbackFor = Exception.class) @Override public boolean saveOrUpdateBatch(Collection<T> entityList, int batchSize) { TableInfo tableInfo = TableInfoHelper.getTableInfo(entityClass); Assert.notNull(tableInfo, "error: can not execute. because can not find cache of TableInfo for entity!"); String keyProperty = tableInfo.getKeyProperty(); Assert.notEmpty(keyProperty, "error: can not execute. because can not find column for id from entity!"); return SqlHelper.saveOrUpdateBatch(this.entityClass, this.mapperClass, this.log, entityList, batchSize, (sqlSession, entity) -> { Object idVal = ReflectionKit.getFieldValue(entity, keyProperty); return StringUtils.checkValNull(idVal) || CollectionUtils.isEmpty(sqlSession.selectList(getSqlStatement(SqlMethod.SELECT_BY_ID), entity)); }, (sqlSession, entity) -> { MapperMethod.ParamMap<T> param = new MapperMethod.ParamMap<>(); param.put(Constants.ENTITY, entity); sqlSession.update(getSqlStatement(SqlMethod.UPDATE_BY_ID), param); }); } @Transactional(rollbackFor = Exception.class) @Override public boolean updateBatchById(Collection<T> entityList, int batchSize) { String sqlStatement = getSqlStatement(SqlMethod.UPDATE_BY_ID); return executeBatch(entityList, batchSize, (sqlSession, entity) -> { MapperMethod.ParamMap<T> param = new MapperMethod.ParamMap<>(); param.put(Constants.ENTITY, entity); sqlSession.update(sqlStatement, param); }); } @Override public T getOne(Wrapper<T> queryWrapper, boolean throwEx) { if (throwEx) { return baseMapper.selectOne(queryWrapper); } return SqlHelper.getObject(log, baseMapper.selectList(queryWrapper)); } @Override public Map<String, Object> getMap(Wrapper<T> queryWrapper) { return SqlHelper.getObject(log, baseMapper.selectMaps(queryWrapper)); } @Override public <V> V getObj(Wrapper<T> queryWrapper, Function<? super Object, V> mapper) { return SqlHelper.getObject(log, listObjs(queryWrapper, mapper)); } /** * 执行批量操作 * * @param consumer consumer * @since 3.3.0 * @deprecated 3.3.1 后面我打算移除掉 {@link #executeBatch(Collection, int, BiConsumer)} }. */ @Deprecated protected boolean executeBatch(Consumer<SqlSession> consumer) { return SqlHelper.executeBatch(this.entityClass, this.log, consumer); } /** * 执行批量操作 * * @param list 数据集合 * @param batchSize 批量大小 * @param consumer 执行方法 * @param <E> 泛型 * @return 操作结果 * @since 3.3.1 */ protected <E> boolean executeBatch(Collection<E> list, int batchSize, BiConsumer<SqlSession, E> consumer) { return SqlHelper.executeBatch(this.entityClass, this.log, list, batchSize, consumer); } /** * 执行批量操作（默认批次提交数量{@link IService#DEFAULT_BATCH_SIZE}） * * @param list 数据集合 * @param consumer 执行方法 * @param <E> 泛型 * @return 操作结果 * @since 3.3.1 */ protected <E> boolean executeBatch(Collection<E> list, BiConsumer<SqlSession, E> consumer) { return executeBatch(list, DEFAULT_BATCH_SIZE, consumer); }}
1.getBaseMapper()
2.getEntityClass()
3.saveBatch()
4.saveOrUpdate()
5.saveOrUpdateBatch()
6.updateBatchById()
7.getOne()
8.getMap()
9.getObj()
1.log：打印日志
2.baseMapper：实现了许多的SQL操作
3.entityClass：实体类
4.mapperClass：映射类
ServiceImpl类中有这个类的成员变量，因此通过ServiceImpl这个类便能够操作如下方法：
1.int insert(T entity);：插入记录
2.int deleteById(Serializable id);：通过id删除指定记录
3.int deleteByMap(Map<String, Object> columnMap)：通过Map集合添加删除指定记录
4.int delete(@Param(Constants.WRAPPER) Wrapper queryWrapper)：通过添加构造器删除指定记录
5.int deleteBatchIds(Collection<? extends Serializable> idList)：通过List集合批量删除记录
6.int updateById(T entity)：根据id修改指定记录
7.int update(T entity, Wrapper updateWrapper)：根据条件构造器
8.T selectById(Serializable id)：根据id查询指定记录
9.List selectBatchIds(Collection<? extends Serializable> idList)：根据List集合批量查询记录
10.List selectByMap(Map<String, Object> columnMap)：根据Map集合查询记录
11.T selectOne(Wrapper queryWrapper)：根据条件构造器查询一条记录
12.Integer selectCount(Wrapper queryWrapper)：根据条件构造器查询记录总数
13.List selectList(Wrapper queryWrapper)：根据条件构造器查询全部记录
14.List<Map<String, Object>> selectMaps(Wrapper queryWrapper)：根据条件构造器查询全部记录
15.ist selectObjs(Wrapper queryWrapper)：根据条件构造器查询全部记录
16.<E extends IPage> E selectPage(E page, Wrapper queryWrapper)：根据条件构造器查询全部记录（并翻页）
17.<E extends IPage<Map<String, Object>>> E selectMapsPage(E page, Wrapper queryWrapper)：根据条件构造器查询全部记录（并翻页）
1.getEntity()：实体对象（子类实现）
2.getSqlSelectgetSqlSet()：
3.getSqlComment()：
4.getSqlFirst()：
5.getExpression()：获取 MergeSegments
6.getCustomSqlSegment()：获取自定义SQL 简化自定义XML复杂情况
7.isEmptyOfWhere()：查询条件为空(包含entity)
8.nonEmptyOfWhere()：查询条件不为空(包含entity)
9.isEmptyOfNormal()：查询条件为空(不包含entity)
10.nonEmptyOfNormal()：查询条件为空(不包含entity)
11.nonEmptyOfEntity()：深层实体判断属性
12.fieldStrategyMatch()：根据实体FieldStrategy属性来决定判断逻辑
13.isEmptyOfEntity()：深层实体判断属性
14.getTargetSql()：获取格式化后的执行sql
15.clear()：条件清空
实例说明
public class ServiceImpl<M extends BaseMapper<T>, T> implements IService<T> {}public class CategoryServiceImpl extends ServiceImpl<CategoryDao, CategoryEntity> implements CategoryService {}
在ServiceImpl中已经注入了Mapper对象： protected M baseMapper；因此XXXServiceImpl只要继承了这个原生的ServiceImpl，这个M实体Dao就已经注入了进来，不需要重新注入。
