public class TenantLineInnerInterceptor extends JsqlParserSupport implements InnerInterceptor {// 多租户处理器private TenantLineHandler tenantLineHandler;// 改SQL，添加多租户id条件public void beforeQuery(Executor executor, MAppedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {if (!InterceptorIgnoreHelper.willIgnoreTenantLine(ms.getId())) {MPBoundSql mpBs = PluginUtils.mpBoundSql(boundSql);mpBs.sql(this.parserSingle(mpBs.sql(), (Object)null));}}public void beforePrepare(StatementHandler sh, Connection connection, Integer transactionTimeout) {MPStatementHandler mpSh = PluginUtils.mpStatementHandler(sh);MappedStatement ms = mpSh.mappedStatement();SqlCommandType sct = ms.getSqlCommandType();if (sct == SqlCommandType.INSERT || sct == SqlCommandType.UPDATE || sct == SqlCommandType.DELETE) {if (InterceptorIgnoreHelper.willIgnoreTenantLine(ms.getId())) {return;}MPBoundSql mpBs = mpSh.mPBoundSql();mpBs.sql(this.parserMulti(mpBs.sql(), (Object)null));}}// 碍于篇幅问题，下面省略的代码就是继承抽象类JsqlParserSupport解析SQL然后添加多租户id条件的，可以自行查看源码......}接着我们来看看处理器TenantLineHandler，这是一个接口，需要我们提供自定义实现，指定多租户相关配置：
public class TenantDatabaseHandler implements TenantLineHandler {private final Set<String> ignoreTables = new HashSet<>();public TenantDatabaseHandler(TenantProperties properties) {// 将配置文件配置的忽略表名同步大小写，适配不同写法properties.getIgnoreTables().forEach(table -> {ignoreTables.add(table.toLowerCase());ignoreTables.add(table.toUpperCase());});}/*** 获取租户字段名* <p>* 默认字段名叫: tenant_id，我这里使用org_id** @return 租户字段名*/@Overridepublic String getTenantIdColumn() {return "org_id";}@Overridepublic Expression getTenantId() {// 这里通过登录信息上下文返回租户id给多租户拦截器增强SQL使用return new LongValue(RequestUserHolder.getCurrentUser().getOrgId());}@Overridepublic boolean ignoreTable(String tableName) {// 忽略多租户的表return CollUtil.contAIns(ignoreTables, tableName);}}配置属性如下：
@ConfigurationProperties(prefix = "ptc.tenant")@Datapublic class TenantProperties {/*** 全局控制是否开启多租户功能*/private Boolean enable = Boolean.TRUE;/*** 需要忽略多租户的表** 即默认所有表都开启多租户的功能，所以记得添加对应的 tenant_id 字段哟*/private Set<String> ignoreTables = Collections.emptySet();}接下来注入拦截器插件即可：
@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor(TenantProperties properties) {MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();// 必须保证多租户插件在分页插件之前，这个是 MyBatis-plus 的规定if (properties.getEnable()) {mybatisPlusInterceptor.addInnerInterceptor(new TenantLineInnerInterceptor(new TenantDatabaseHandler(properties)));}// 分页插件mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());return mybatisPlusInterceptor;}使用示例如下：这里提供了一个常见的案例：用户和角色关联查询的SQL：getUserList()
<select id="getUserList" resultType="com.plasticene.textile.entity.User">select u.* from user uleft join user_role r on u.id = r.user_id<where><if test="query.status != null">and u.status = #{query.status}</if><if test="query.roleId != null">and r.role_id = #{query.roleId}</if><if test="query.keyword != null">and ((u.name like concat('%',#{query.keyword},'%')) or (u.mobile like concat(#{query.keyword},'%')))</if><if test="query.startEntryTime != null">and u.entry_time >= #{query.startEntryTime}</if><if test="query.endEntryTime != null"><![CDATA[ and u.entry_time <= #{query.endEntryTime}]]></if></where>group by u.idorder by u.id desc</select>启动项目，先登录之后使用token掉接口执行下面代码逻辑：
public PageResult<UserDTO> getList(UserQuery query) {Page<UserDTO> page = new Page<>(query.getPageNo(), query.getPageSize());List<User> userList = userDAO.getUserList(page, query);List<UserDTO> userDTOS = toUserDTOList(userList);return new PageResult<>(userDTOS, page.getTotal(), page.getPages());}查看控制台发现：
[1658720355293990912] [DEBUG] [2023-05-17 14:25:25.504] [http-nio-16688-exec-1@23652]com.plasticene.textile.dao.UserDAO.getUserList debug : ==>Preparing: SELECT u.* FROM user u LEFT JOIN user_role r ON u.id = r.user_id AND r.org_id = 3 WHERE u.org_id = 3 GROUP BY u.id ORDER BY u.id DESC LIMIT ?[1658720355293990912] [DEBUG] [2023-05-17 14:25:25.505] [http-nio-16688-exec-1@23652]com.plasticene.textile.dao.UserDAO.getUserList debug : ==> Parameters: 20(Long)