在使用了Mybatis Plus框架进行项目重构之后,关于如何更好的利用Mybatis plus。在此做一些总结供大家参考。
主要总结了以下这几个方面的实践。
?基础设计
oBaseEntity
o逻辑删除
o自动填充字段
?代码生成类
?查询操作
oQuery基类(复用+PageQuery)
o普通Query
oLambda Query
o复杂多表查询
o报表型查询
?保存操作
o模型利用JPA保存
o批量保存数据
o按条件更新数据
?扩展
o阻止全表操作
o动态数据源
o多租户
详细代码实现在开源项目Agileboot中:https://github.com/valarchie/AgileBoot-Back-End关于Mybatis Plus的实践,如有不足或者建议欢迎大家评论指正。
基础设计
BaseEntity
对于数据库中表中的公共字段我们可以抽取出来做成基类继承。避免表映射的数据库实体类字段太过繁杂。例如常用的创建时间、创建者、更新时间、更新者、逻辑删除字段。
/**
?* Entity基类
?*
?* @author valarchie
?*/@EqualsAndHashCode(callSuper = true)@Data
public class BaseEntity<T extends Model<?>> extends Model<T> {
????@ApiModelProperty("创建者ID")
????@TableField(value = "creator_id", fill = FieldFill.INSERT)
????private Long creatorId;
????@ApiModelProperty("创建时间")
????@TableField(value = "create_time", fill = FieldFill.INSERT)
????private Date createTime;
????@ApiModelProperty("更新者ID")
????@TableField(value = "updater_id", fill = FieldFill.UPDATE, updateStrategy = FieldStrategy.NOT_NULL)
????private Long updaterId;
????@ApiModelProperty("更新时间")
????@TableField(value = "update_time", fill = FieldFill.UPDATE)
????private Date updateTime;
????/**
?????* deleted字段请在数据库中 设置为tinyInt ??并且非null ??默认值为0
?????*/
????@ApiModelProperty("删除标志(0代表存在 1代表删除)")
????@TableField("deleted")
????@TableLogic
????private Boolean deleted;
}复制代码
通过继承了基类,实体类看起来就简洁了许多。
**
?* <p>
?* 通知公告表
?* </p>
?*
?* @author?valarchie
?* @since?2022-10-02
?*/@Getter@Setter@TableName("sys_notice")@ApiModel(value = "SysNoticeEntity对象", description = "通知公告表")public?class?SysNoticeEntity?extends?BaseEntity<SysNoticeEntity> {
????private?static final?long serialVersionUID = 1L;
????@ApiModelProperty("公告ID")
????@TableId(value = "notice_id", type = IdType.AUTO)
????private?Integer noticeId;
????@ApiModelProperty("公告标题")
????@TableField("notice_title")
????private?String noticeTitle;
????@ApiModelProperty("公告类型(1通知 2公告)")
????@TableField("notice_type")
????private?Integer noticeType;
????@ApiModelProperty("公告内容")
????@TableField("notice_content")
????private?String noticeContent;
????@ApiModelProperty("公告状态(1正常 0关闭)")
????@TableField("`status`")
????private?Integer status;
????@ApiModelProperty("备注")
????@TableField("remark")
????private?String remark;
????@Override
????public?Serializable pkVal() {
????????return?this.noticeId;
????}
}复制代码
既然抽取出了公共字段,我们可以更进一步将这些公共字段进行自动填值处理。Mybatis Plus提供了字段自动填充的插件。
自动填充字段
**
?* Mybatis Plus允许在插入或者更新的时候
?* 自定义设定值
?* @author?valarchie
?*/@Component@Slf4jpublic?class?CustomMetaObjectHandler?implements?MetaObjectHandler?{
????public?static?final?String?CREATE_TIME_FIELD?=?"createTime";
????public?static?final?String?CREATOR_ID_FIELD?=?"creatorId";
????public?static?final?String?UPDATE_TIME_FIELD?=?"updateTime";
????public?static?final?String?UPDATER_ID_FIELD?=?"updaterId";
????@Override
????public?void?insertFill(MetaObject metaObject)?{
????????if?(metaObject.hasSetter(CREATE_TIME_FIELD)) {
????????????this.setFieldValByName(CREATE_TIME_FIELD, new?Date(), metaObject);
????????}
????????if?(metaObject.hasSetter(CREATOR_ID_FIELD)) {
????????????this.strictInsertFill(metaObject, CREATOR_ID_FIELD, Long.class, getUserIdSafely());
????????}
????}
????@Override
????public?void?updateFill(MetaObject metaObject)?{
????????if?(metaObject.hasSetter(UPDATE_TIME_FIELD)) {
????????????this.setFieldValByName(UPDATE_TIME_FIELD, new?Date(), metaObject);
????????}
????????if?(metaObject.hasSetter(UPDATER_ID_FIELD)) {
????????????this.strictUpdateFill(metaObject, UPDATER_ID_FIELD, Long.class, getUserIdSafely());
????????}
????}
????public?Long getUserIdSafely()?{
????????Long?userId?=?null;
????????try?{
????????????LoginUser?loginUser?=?AuthenticationUtils.getLoginUser();
????????????userId = loginUser.getUserId();
????????} catch?(Exception e) {
????????????log.info("can not find user in current thread.");
????????}
????????return?userId;
????}
}复制代码
使用自定义填充值时,需要在生成实体的时候加上配置。FieldFill.INSERT?和?FieldFill.INSERT_UPDATE
private?void entityConfig(StrategyConfig.Builder builder) {
????Entity.Builder entityBuilder = builder.entityBuilder();
????entityBuilder
????????.enableLombok()
????????.addTableFills(new?Column("create_time", FieldFill.INSERT))
????????.addTableFills(new?Column("creator_id", FieldFill.INSERT))
????????.addTableFills(new?Property("updateTime", FieldFill.INSERT_UPDATE))
????????.addTableFills(new?Property("updaterId", FieldFill.INSERT_UPDATE))
????????// ID strategy AUTO, NONE, INPUT, ASSIGN_ID, ASSIGN_UUID;
????????.idType(IdType.AUTO)
????????.formatFileName("%sEntity");
????if?(isExtendsFromBaseEntity) {
????????entityBuilder
????????????.superClass(BaseEntity.class)
????????????.addSuperEntityColumns("creator_id", "create_time", "creator_name", "updater_id", "update_time",
????????????????"updater_name", "deleted");
????}
????entityBuilder.build();
}复制代码
逻辑删除
数据库一般不进行真实删除操作。但是如果让我们手工处理这些逻辑删除的话,也是非常麻烦。Mybatis Plus有提供这样的插件。仅需要在EntityConfig中设置逻辑删除的字段是哪个即可。
entityBuilder
????// deleted的字段设置成tinyint ?长度为1
????.logicDeleteColumnName("deleted")
????.formatFileName("%sEntity");复制代码
代码生成类
Mybatis plus支持生成entity,mapper,service,controller这四层类。 但是笔者认为生成类的时候还是不要直接覆盖原本的类比较好。我将生成的类,固定放在一个目录让使用者自己copy类到指定的目录。以下是我自己封装的CodeGenerator的代码片段。需要填入的字段主要是:
[if !supportLists]·?[endif]作者名
[if !supportLists]·?[endif]包名
[if !supportLists]·?[endif]表名
[if !supportLists]·?[endif]是否需要继承基类(因为不是所有表都需要继承基类)
public static void main(String[] args) {
????// 默认读取application-dev yml中的master数据库配置
????JSON ymlJson = JSONUtil.parse(new Yaml().load(ResourceUtil.getStream("application-dev.yml")));
????CodeGenerator generator = CodeGenerator.builder()
????????.databaseUrl(JSONUtil.getByPath(ymlJson, URL_PATH).toString())
????????.username(JSONUtil.getByPath(ymlJson, USERNAME_PATH).toString())
????????.password(JSONUtil.getByPath(ymlJson, PASSWORD_PATH).toString())
????????.author("valarchie")
????????//生成的类 放在orm子模块下的/target/generated-code目录底下
????????.module("/agileboot-orm/target/generated-code")
????????.parentPackage("com.agileboot")
????????.tableName("sys_config")
????????// 决定是否继承基类
????????.isExtendsFromBaseEntity(true)
????????.build();
????generator.generateCode();
}复制代码
查询操作
Query基类
系统内的查询大部分有共用的逻辑。比如时间范围的查询、排序。我们可以抽取这部分逻辑放在基类。然后把具体查询条件的构造,放到子类去实现。
AbstractQuery
/**
?* @author?valarchie
?*/@Datapublic?abstract?class?AbstractQuery<T> {
????protected?String?orderByColumn;
????protected?String?isAsc;
????@JsonFormat(shape = Shape.STRING, pattern = "yyyy-MM-dd")
????private?Date?beginTime;
????@JsonFormat(shape = Shape.STRING, pattern = "yyyy-MM-dd")
????private?Date?endTime;
????private?static?final String?ASC?= "ascending";
????private?static?final String?DESC?= "descending";
????/**
?????* 生成query conditions
?????* @return
?????*/
????public?abstract?QueryWrapper<T> toQueryWrapper();
????public?void?addSortCondition(QueryWrapper<T> queryWrapper) {
????????if(queryWrapper != null) {
????????????boolean?sortDirection = convertSortDirection();
????????????queryWrapper.orderBy(StrUtil.isNotBlank(orderByColumn), sortDirection,
????????????????StrUtil.toUnderlineCase(orderByColumn));
????????}
????}
????public?void?addTimeCondition(QueryWrapper<T> queryWrapper, String?fieldName) {
????????if?(queryWrapper != null) {
????????????queryWrapper
????????????????.ge(beginTime != null, fieldName, DatePickUtil.getBeginOfTheDay(beginTime))
????????????????.le(endTime != null, fieldName, DatePickUtil.getEndOfTheDay(endTime));
????????}
????}
????public?boolean?convertSortDirection() {
????????boolean?orderDirection = true;
????????if?(StrUtil.isNotEmpty(isAsc)) {
????????????if?(ASC.equals(isAsc)) {
????????????????orderDirection = true;
????????????} else?if?(DESC.equals(isAsc)) {
????????????????orderDirection = false;
????????????}
????????}
????????return?orderDirection;
????}
}复制代码
PageQuery
分页是非常常见的查询条件,我们可以基于AbstractQuery再做一层封装。
/**
?* @author?valarchie
?*/@Datapublic?abstract?class?AbstractPageQuery<T> extends?AbstractQuery<T> {
????public?static?final?int?MAX_PAGE_NUM?=?200;
????public?static?final?int?MAX_PAGE_SIZE?=?500;
????@Max(MAX_PAGE_NUM)
????protected?Integer?pageNum?=?1;
????@Max(MAX_PAGE_SIZE)
????protected?Integer?pageSize?=?10;
????public?Page<T> toPage()?{
????????return?new?Page<>(pageNum, pageSize);
????}
}复制代码
普通Query
比如我们有个菜单查询列表,我们可以新建一个MenuQuery继承AbstractQuery。然后实现 toQueryWrapper方法去构造查询条件。
/**
?* @author valarchie
?*/@Data
public class?MenuQuery?extends?AbstractQuery<SysMenuEntity>?{
????private?String?menuName;
????private?Boolean?isVisible;
????private?Integer?status;
????@Override
????public QueryWrapper<SysMenuEntity> toQueryWrapper() {
????????QueryWrapper<SysMenuEntity> queryWrapper = new?QueryWrapper<SysMenuEntity>()
????????????.like(StrUtil.isNotEmpty(menuName), "menu_name", menuName)
????????????.eq(isVisible != null, "is_visible", isVisible)
????????????.eq(status != null, "status", status);
????????queryWrapper.orderBy(true, true, Arrays.asList("parent_id", "order_num"));
????????return?queryWrapper;
????}
}复制代码
如果有另外一个不同的菜单查询列表,查询的参数一样,但是查询条件的构造不一样。我们可以新建一个DifferentMenuQuery类继承MenuQuery类,再覆写toQueryWrapper方法即可。
Lambda Query
如果在项目中的查询明确是单表操作的话,我们可以使用LambdaQuery来构造查询。
LambdaQueryWrapper<SysMenuEntity> menuQuery?= Wrappers.lambdaQuery();
menuQuery.select(SysMenuEntity::getMenuId);
List<SysMenuEntity> menuList?= menuService.list(menuQuery);复制代码
复杂多表查询
Mybatis Plus支持@Select注解,遇到简单的多表join查询的话,我们可以直接在代码中写SQL语句。
以下是Mapper中的实现。${ew.customSqlSegment}?会渲染出QueryWrapper类生成的查询条件。
/**
?* 根据条件分页查询用户列表
?* @param page 页码对象
?* @param queryWrapper 查询对象
?* @return 用户信息集合信息
?*/@Select("SELECT u.*, d.dept_name, d.leader_name "
????+ "FROM sys_user u "
????+ " LEFT JOIN sys_dept d ON u.dept_id = d.dept_id "
????+ "${ew.customSqlSegment}")
Page<SearchUserDO> getUserList(Page<SearchUserDO> page,
????@Param(Constants.WRAPPER) Wrapper<SearchUserDO> queryWrapper);复制代码
Service层中的实现。
@Overridepublic?Page<SearchUserDO> getUserList(AbstractPageQuery<SearchUserDO> query) {
????return?baseMapper.getUserList(query.toPage(), query.toQueryWrapper());
}复制代码
报表型查询
如果遇到复杂的报表型查询,利用@Select注解的话,可能SQL看起来还是非常的复杂。此时推荐使用XML的形式。
保存操作
模型利用JPA保存
Mybatis Plus支持activeRecord特性,我们可以直接在Entity上执行save\update\delete等操作。框架会自动帮我们落库。 activeRecord需要在EntityConfig配置。
????????entityBuilder
????????????// operate entity like JPA.
????????????.enableActiveRecord()
????????????// deleted的字段设置成tinyint ?长度为1
????????????// ID strategy AUTO, NONE, INPUT, ASSIGN_ID, ASSIGN_UUID;
????????????.idType(IdType.AUTO)
????????????.formatFileName("%sEntity");复制代码
因为Entity都是生成的,我们不方便将业务逻辑直接放在Entity中。这样会和数据库实体过于耦合。推荐新建一个模型类继承XxxxEntity,然后将逻辑填充在模型类中。
public class DeptModel extends SysDeptEntity {
????private ISysDeptService deptService;
????public DeptModel(ISysDeptService deptService) {
????????this.deptService?= deptService;
????}
????public DeptModel(SysDeptEntity entity, ISysDeptService deptService) {
????????if (entity != null) {
????????????// 如果大数据量的话 ?可以用MapStruct优化
????????????BeanUtil.copyProperties(entity, this);
????????}
????????this.deptService?= deptService;
????}
????public void loadAddCommand(AddDeptCommand addCommand) {
????????this.setParentId(addCommand.getParentId());
????????this.setAncestors(addCommand.getAncestors());
????????this.setDeptName(addCommand.getDeptName());
????????this.setOrderNum(addCommand.getOrderNum());
????????this.setLeaderName(addCommand.getLeaderName());
????????this.setPhone(addCommand.getPhone());
????????this.setEmail(addCommand.getEmail());
????}
????public void checkDeptNameUnique() {
????????if (deptService.isDeptNameDuplicated(getDeptName(), getDeptId(), getParentId())) {
????????????throw new ApiException(ErrorCode.Business.DEPT_NAME_IS_NOT_UNIQUE, getDeptName());
????????}
????}
????public void generateAncestors() {
????????if (getParentId() == 0) {
????????????setAncestors(getParentId().toString());
????????????return;
????????}
????????SysDeptEntity parentDept = deptService.getById(getParentId());
????????if (parentDept == null || StatusEnum.DISABLE.equals(
????????????BasicEnumUtil.fromValue(StatusEnum.class, parentDept.getStatus()))) {
????????????throw new ApiException(ErrorCode.Business.DEPT_PARENT_DEPT_NO_EXIST_OR_DISABLED);
????????}
????????setAncestors(parentDept.getAncestors() + "," + getParentId());
????}
}复制代码
在应用层我们就可以直接调用模型类来完成逻辑操作。整个代码的语义性非常强。
public void addDept(AddDeptCommand addCommand) {
????DeptModel deptModel?= deptModelFactory.create();
????deptModel.loadAddCommand(addCommand);
????deptModel.checkDeptNameUnique();
????deptModel.generateAncestors();
????deptModel.insert();
}复制代码
批量保存数据
以上是单条数据的落库操作,那么多条数据循环去insert的话,显然不是一个明智之举。Mybatis Plus提供了批量落库操作。
private boolean saveMenus() {
????List<SysRoleMenuEntity> list?= new ArrayList<>();
????if (getMenuIds() != null) {
????????for (Long menuId : getMenuIds()) {
????????????SysRoleMenuEntity rm?= new SysRoleMenuEntity();
????????????rm.setRoleId(getRoleId());
????????????rm.setMenuId(menuId);
????????????list.add(rm);
????????}
????????return roleMenuService.saveBatch(list);
????}
????return false;
}复制代码
按条件更新数据
JPA的方式有一个弊端就是需要先拿到数据实体类,才能调用save等操作。还有一种情况,我们需要按照某些条件去更新数据,而不想先一条条获取数据再Save。此时可以使用LambdaUpdate类。
LambdaUpdateWrapper<SysUserEntity> updateWrapper?= new LambdaUpdateWrapper<>();
updateWrapper.set(SysUserEntity::getRoleId, null).eq(SysUserEntity::getUserId, userId);
userService.update(updateWrapper);复制代码
扩展
阻止全表操作
Mybatis Plus提供了安全方面的插件,比如阻止全标更新删除的插件。仅需要声明MybatisPlusInterceptor Bean,依次添加拦截插件即可。
@Beanpublic?MybatisPlusInterceptor mybatisPlusInterceptor()?{
????MybatisPlusInterceptor?interceptor?=?new?MybatisPlusInterceptor();
????interceptor.addInnerInterceptor(new?BlockAttackInnerInterceptor());
????return?interceptor;
}复制代码
动态数据源
Mybatis Plus提供@DS注解去动态选择从库还是主库来执行SQL.
@DS("slave")@PreAuthorize("@permission.has('system:notice:list')")@GetMapping("/listFromSlave")
public ResponseDTO<PageDTO<NoticeDTO>> listFromSlave(NoticeQuery query) {
????PageDTO<NoticeDTO> pageDTO?= noticeApplicationService.getNoticeList(query);
????return?ResponseDTO.ok(pageDTO);
}复制代码
比如打上了@DS("slave")的接口,就会去找slave这个从库进行操作。
多租户
????@Bean
????public MybatisPlusInterceptor mybatisPlusInterceptor() {
????????MybatisPlusInterceptor?interceptor?= new?MybatisPlusInterceptor();
????????interceptor.addInnerInterceptor(new TenantLineInnerInterceptor(new TenantLineHandler() {
????????????@Override
????????????public Expression getTenantId() {
????????????????// 获取租户ID 实际应该从用户信息中获取
????????????????return new LongValue(1);
????????????}
????????????// 这是 default 方法,默认返回 false 表示所有表都需要拼多租户条件
????????????@Override
????????????public boolean ignoreTable(String tableName) {
????????????????return !"sys_user".equalsIgnoreCase(tableName);
????????????}
????????}));
????????// 如果用了分页插件注意先 add TenantLineInnerInterceptor 再 add PaginationInnerInterceptor
????????// 用了分页插件必须设置 MybatisConfiguration#useDeprecatedExecutor = false// ???????interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
????????return?interceptor;
????}