前言
本篇主要分析Mybatis-plus 多租户插件，然后根据多租户插件在延伸到其他场景
案例
Mybatis-plus官网对多租户插件已有详细讲解，这里就不在附上使用案例。
源码分析
MybatisPlus官方是由TenantLineInnerInterceptor这个拦截器进行多租户功能处理，所以，本篇章主要对TenantLineInnerInterceptor这个类的讲解。
TenantLineInnerInterceptor
java
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
@SuppressWarnings({"rawtypes"})
public class TenantLineInnerInterceptor extends BaseMultiTableInnerInterceptor implements InnerInterceptor {
/**
* 租户处理器（ TenantId 行级 ）
*/
private TenantLineHandler tenantLineHandler;
/**
* 查询前sql语句的处理
* @param executor Executor(可能是代理对象)
* @param ms MappedStatement
* @param parameter parameter
* @param rowBounds rowBounds
* @param resultHandler resultHandler
* @param boundSql boundSql
* @throws SQLException
*/
@Override
public void beforeQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
if (InterceptorIgnoreHelper.willIgnoreTenantLine(ms.getId())) {
return;
}
PluginUtils.MPBoundSql mpBs = PluginUtils.mpBoundSql(boundSql);
mpBs.sql(parserSingle(mpBs.sql(), null));
}
/**
* 执行前的处理
* @param sh StatementHandler(可能是代理对象)
* @param connection Connection
* @param transactionTimeout transactionTimeout
*/
@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.INSERT || sct == SqlCommandType.UPDATE || sct == SqlCommandType.DELETE) {
if (InterceptorIgnoreHelper.willIgnoreTenantLine(ms.getId())) {
return;
}
PluginUtils.MPBoundSql mpBs = mpSh.mPBoundSql();
mpBs.sql(parserMulti(mpBs.sql(), null));
}
}
/**
* sql select语法处理
* @param select
* @param index
* @param sql
* @param obj
*/
@Override
protected void processSelect(Select select, int index, String sql, Object obj) {
final String whereSegment = (String) obj;
processSelectBody(select, whereSegment);
List<WithItem> withItemsList = select.getWithItemsList();
if (!CollectionUtils.isEmpty(withItemsList)) {
withItemsList.forEach(withItem -> processSelectBody(withItem, whereSegment));
}
}
/**
* sql 语法处理
* @param insert
* @param index
* @param sql
* @param obj
*/
@Override
protected void processInsert(Insert insert, int index, String sql, Object obj) {
if (tenantLineHandler.ignoreTable(insert.getTable().getName())) {
// 过滤退出执行
return;
}
List<Column> columns = insert.getColumns();
if (CollectionUtils.isEmpty(columns)) {
// 针对不给列名的insert 不处理
return;
}
String tenantIdColumn = tenantLineHandler.getTenantIdColumn();
if (tenantLineHandler.ignoreInsert(columns, tenantIdColumn)) {
// 针对已给出租户列的insert 不处理
return;
}
columns.add(new Column(tenantIdColumn));
Expression tenantId = tenantLineHandler.getTenantId();
// fixed gitee pulls/141 duplicate update
List<UpdateSet> duplicateUpdateColumns = insert.getDuplicateUpdateSets();
if (CollectionUtils.isNotEmpty(duplicateUpdateColumns)) {
duplicateUpdateColumns.add(new UpdateSet(new Column(tenantIdColumn), tenantId));
}
Select select = insert.getSelect();
if (select instanceof PlainSelect) { //fix github issue 4998 修复升级到4.5版本的问题
this.processInsertSelect(select, (String) obj);
} else if (insert.getValues() != null) {
// fixed github pull/295
Values values = insert.getValues();
ExpressionList<Expression> expressions = (ExpressionList<Expression>) values.getExpressions();
if (expressions instanceof ParenthesedExpressionList) {
expressions.addExpression(tenantId);
} else {
if (CollectionUtils.isNotEmpty(expressions)) {//fix github issue 4998 jsqlparse 4.5 批量insert ItemsList不是MultiExpressionList 了，需要特殊处理
int len = expressions.size();
for (int i = 0; i < len; i++) {
Expression expression = expressions.get(i);
if (expression instanceof ParenthesedExpressionList) {
((ParenthesedExpressionList<Expression>) expression).addExpression(tenantId);
} else {
expressions.add(tenantId);
}
}
} else {
expressions.add(tenantId);
}
}
} else {
throw ExceptionUtils.mpe("Failed to process multiple-table update, please exclude the tableName or statementId");
}
}
/**
* update 语句处理
*/
@Override
protected void processUpdate(Update update, int index, String sql, Object obj) {
final Table table = update.getTable();
if (tenantLineHandler.ignoreTable(table.getName())) {
// 过滤退出执行
return;
}
List<UpdateSet> sets = update.getUpdateSets();
if (!CollectionUtils.isEmpty(sets)) {
sets.forEach(us -> us.getValues().forEach(ex -> {
if (ex instanceof Select) {
processSelectBody(((Select) ex), (String) obj);
}
}));
}
update.setWhere(this.andExpression(table, update.getWhere(), (String) obj));
}
/**
* delete 语句处理
*/
@Override
protected void processDelete(Delete delete, int index, String sql, Object obj) {
if (tenantLineHandler.ignoreTable(delete.getTable().getName())) {
// 过滤退出执行
return;
}
delete.setWhere(this.andExpression(delete.getTable(), delete.getWhere(), (String) obj));
}
/**
* 处理 insert into select
* <p>
* 进入这里表示需要 insert 的表启用了多租户,则 select 的表都启动了
*
* @param selectBody SelectBody
*/
protected void processInsertSelect(Select selectBody, final String whereSegment) {
if(selectBody instanceof PlainSelect){
PlainSelect plainSelect = (PlainSelect) selectBody;
FromItem fromItem = plainSelect.getFromItem();
if (fromItem instanceof Table) {
// fixed gitee pulls/141 duplicate update
processPlainSelect(plainSelect, whereSegment);
appendSelectItem(plainSelect.getSelectItems());
} else if (fromItem instanceof Select) {
Select subSelect = (Select) fromItem;
appendSelectItem(plainSelect.getSelectItems());
processInsertSelect(subSelect, whereSegment);
}
} else if(selectBody instanceof ParenthesedSelect){
ParenthesedSelect parenthesedSelect = (ParenthesedSelect) selectBody;
processInsertSelect(parenthesedSelect.getSelect(), whereSegment);
}
}
/**
* 追加 SelectItem
*
* @param selectItems SelectItem
*/
protected void appendSelectItem(List<SelectItem<?>> selectItems) {
if (CollectionUtils.isEmpty(selectItems)) {
return;
}
if (selectItems.size() == 1) {
SelectItem item = selectItems.get(0);
Expression expression = item.getExpression();
if (expression instanceof AllColumns) {
return;
}
}
selectItems.add(new SelectItem<>(new Column(tenantLineHandler.getTenantIdColumn())));
}
/**
* 租户字段别名设置
* <p>tenantId 或 tableAlias.tenantId</p>
*
* @param table 表对象
* @return 字段
*/
protected Column getAliasColumn(Table table) {
StringBuilder column = new StringBuilder();
// todo 该起别名就要起别名,禁止修改此处逻辑
if (table.getAlias() != null) {
column.append(table.getAlias().getName()).append(StringPool.DOT);
}
column.append(tenantLineHandler.getTenantIdColumn());
return new Column(column.toString());
}
@Override
public void setProperties(Properties properties) {
PropertyMapper.newInstance(properties).whenNotBlank("tenantLineHandler",
ClassUtils::newInstance, this::setTenantLineHandler);
}
/**
* 构建租户条件表达式
*
* @param table 表对象
* @param where 当前where条件
* @param whereSegment 所属Mapper对象全路径（在原租户拦截器功能中，这个参数并不需要参与相关判断）
* @return 租户条件表达式
* @see BaseMultiTableInnerInterceptor#buildTableExpression(Table, Expression, String)
*/
@Override
public Expression buildTableExpression(final Table table, final Expression where, final String whereSegment) {
if (tenantLineHandler.ignoreTable(table.getName())) {
return null;
}
return new EqualsTo(getAliasColumn(table), tenantLineHandler.getTenantId());
}
}到此本篇完结