@DataColumn(key = “userName”, value = “u.user_id”)注解
src/main/java/com/ruoyi/system/mapper/SysUserMapper.java

@DataPermission({
        @DataColumn(key = "deptName", value = "d.dept_id"),
        @DataColumn(key = "userName", value = "u.user_id")
    })
    Page<SysUser> selectPageUserList(@Param("page") Page<SysUser> page, @Param(Constants.WRAPPER) Wrapper<SysUser> queryWrapper);

src/main/java/com/ruoyi/common/mybatis/config/MybatisPlusConfiguration.java

  /**
     * 数据权限拦截器
     */
    public PlusDataPermissionInterceptor dataPermissionInterceptor() {
        return new PlusDataPermissionInterceptor();
    }

src/main/java/com/ruoyi/common/mybatis/interceptor/PlusDataPermissionInterceptor.java

Override
    public void beforeQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
        // 检查忽略注解
        if (InterceptorIgnoreHelper.willIgnoreDataPermission(ms.getId())) {
            return;
        }
        // 检查是否无效 无数据权限注解
        if (dataPermissionHandler.isInvalid(ms.getId())) {
            return;
        }
        // 解析 sql 分配对应方法
        PluginUtils.MPBoundSql mpBs = PluginUtils.mpBoundSql(boundSql);
        mpBs.sql(parserSingle(mpBs.sql(), ms.getId()));
    }

    @Override
    public void beforePrepare(StatementHandler sh, Connection connection, Integer transactionTimeout) {
        PluginUtils.MPStatementHandler mpSh = PluginUtils.mpStatementHandler(sh);
        MappedStatement ms = mpSh.mappedStatement();
        SqlCommandType sct = ms.getSqlCommandType();
        if (sct == SqlCommandType.UPDATE || sct == SqlCommandType.DELETE) {
            if (InterceptorIgnoreHelper.willIgnoreDataPermission(ms.getId())) {
                return;
            }
            PluginUtils.MPBoundSql mpBs = mpSh.mPBoundSql();
            mpBs.sql(parserMulti(mpBs.sql(), ms.getId()));
        }
    }

src/main/java/com/ruoyi/common/mybatis/enums/DataScopeType.java
需要拼入SysUserMapper中的数据权限

/**
     * 部门及以下数据权限
     */
    DEPT_AND_CHILD("4", " #{#deptName} IN ( #{@sdss.getDeptAndChild( #user.deptId )} )", ""),

src/main/resources/mapper/system/SysUserMapper.xml

<select id="selectUserList" resultMap="SysUserResult">
		select u.user_id, u.dept_id, u.nick_name, u.user_name, u.email, u.avatar, u.phonenumber, u.sex, u.status, u.del_flag, u.login_ip, u.login_date, u.create_by, u.create_time, u.remark, d.dept_name, d.leader from sys_user u
		left join sys_dept d on u.dept_id = d.dept_id
        ${ew.getCustomSqlSegment}
	</select>

src/main/java/com/ruoyi/common/mybatis/annotation/DataColumn.java

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DataColumn {

    /**
     * 占位符关键字
     */
    String[] key() default "deptName";

    /**
     * 占位符替换值
     */
    String[] value() default "dept_id";

}

@sdss.getDeptAndChild对应getDeptAndChild()方法返回值
src/main/java/com/ruoyi/system/dubbo/RemoteDataScopeServiceImpl.java#getDeptAndChild()

  @Override
    public String getDeptAndChild(Long deptId) {
        List<SysDept> deptList = deptMapper.selectList(new LambdaQueryWrapper<SysDept>()
            .select(SysDept::getDeptId)
            .apply(DataBaseHelper.findInSet(deptId, "ancestors")));
        List<Long> ids = StreamUtils.toList(deptList, SysDept::getDeptId);
        ids.add(deptId);
        List<SysDept> list = deptMapper.selectList(new LambdaQueryWrapper<SysDept>()
            .select(SysDept::getDeptId)
            .in(SysDept::getDeptId, ids));
        if (CollUtil.isNotEmpty(list)) {
            return StreamUtils.join(list, d -> Convert.toStr(d.getDeptId()));
        }
        return null;
    }

#user.deptId对应getSqlSegment()当前用户的部门id
src/main/java/com/ruoyi/common/mybatis/handler/PlusDataPermissionHandler.java

 public Expression getSqlSegment(Expression where, String mappedStatementId, boolean isSelect) {
        DataColumn[] dataColumns = findAnnotation(mappedStatementId);
        if (ArrayUtil.isEmpty(dataColumns)) {
            invalidCacheSet.add(mappedStatementId);
            return where;
        }
        LoginUser currentUser = DataPermissionHelper.getVariable("user");
        if (ObjectUtil.isNull(currentUser)) {
            currentUser = LoginHelper.getLoginUser();
            DataPermissionHelper.setVariable("user", currentUser);
        }
        // 如果是超级管理员，则不过滤数据
        if (ObjectUtil.isNull(currentUser) || LoginHelper.isAdmin(currentUser.getUserId())) {
            return where;
        }
        String dataFilterSql = buildDataFilter(dataColumns, isSelect);
        if (StringUtils.isBlank(dataFilterSql)) {
            return where;
        }
        try {
            Expression expression = CCJSqlParserUtil.parseExpression(dataFilterSql);
            // 数据权限使用单独的括号 防止与其他条件冲突
            Parenthesis parenthesis = new Parenthesis(expression);
            if (ObjectUtil.isNotNull(where)) {
                return new AndExpression(where, parenthesis);
            } else {
                return parenthesis;
            }
        } catch (JSQLParserException e) {
            throw new ServiceException("数据权限解析异常 => " + e.getMessage());
        }
    }

如果getDeptAndChild()方法返回值是1，2则SysUserMapper.xml的sql语句解析为

 select u.user_id, u.dept_id, u.nick_name, u.user_name, u.email, u.avatar, u.phonenumber, u.sex,
        u.status, u.del_flag, u.login_ip, u.login_date, u.create_by, u.create_time, u.remark, d.dept_name, d.leader from
        sys_user u
        left join sys_dept d on u.dept_id = d.dept_id
        where d.dept_id IN(1,2)