Java Dialect.forUpdateOfColumns方法代碼示例

import org.hibernate.dialect.Dialect; //導入方法依賴的package包/類
@Override
protected String applyLocks(
		String sql,
		QueryParameters parameters,
		Dialect dialect,
		List<AfterLoadAction> afterLoadActions) throws QueryException {
	// can't cache this stuff either (per-invocation)
	// we are given a map of user-alias -> lock mode
	// create a new map of sql-alias -> lock mode

	final LockOptions lockOptions = parameters.getLockOptions();

	if ( lockOptions == null ||
		( lockOptions.getLockMode() == LockMode.NONE && lockOptions.getAliasLockCount() == 0 ) ) {
		return sql;
	}


	// user is request locking, lets see if we can apply locking directly to the SQL...

	// 		some dialects wont allow locking with paging...
	if ( shouldUseFollowOnLocking( parameters, dialect, afterLoadActions ) ) {
		return sql;
	}

	//		there are other conditions we might want to add here, such as checking the result types etc
	//		but those are better served after we have redone the SQL generation to use ASTs.


	// we need both the set of locks and the columns to reference in locks
	// as the ultimate output of this section...
	final LockOptions locks = new LockOptions( lockOptions.getLockMode() );
	final Map<String, String[]> keyColumnNames = dialect.forUpdateOfColumns() ? new HashMap<String, String[]>() : null;

	locks.setScope( lockOptions.getScope() );
	locks.setTimeOut( lockOptions.getTimeOut() );

	for ( Map.Entry<String, String> entry : sqlAliasByEntityAlias.entrySet() ) {
		final String userAlias =  entry.getKey();
		final String drivingSqlAlias = entry.getValue();
		if ( drivingSqlAlias == null ) {
			throw new IllegalArgumentException( "could not locate alias to apply lock mode : " + userAlias );
		}
		// at this point we have (drivingSqlAlias) the SQL alias of the driving table
		// corresponding to the given user alias.  However, the driving table is not
		// (necessarily) the table against which we want to apply locks.  Mainly,
		// the exception case here is joined-subclass hierarchies where we instead
		// want to apply the lock against the root table (for all other strategies,
		// it just happens that driving and root are the same).
		final QueryNode select = (QueryNode) queryTranslator.getSqlAST();
		final Lockable drivingPersister = (Lockable) select.getFromClause()
				.findFromElementByUserOrSqlAlias( userAlias, drivingSqlAlias )
				.getQueryable();
		final String sqlAlias = drivingPersister.getRootTableAlias( drivingSqlAlias );

		final LockMode effectiveLockMode = lockOptions.getEffectiveLockMode( userAlias );
		locks.setAliasSpecificLockMode( sqlAlias, effectiveLockMode );

		if ( keyColumnNames != null ) {
			keyColumnNames.put( sqlAlias, drivingPersister.getRootTableIdentifierColumnNames() );
		}
	}

	// apply the collected locks and columns
	return dialect.applyLocksToSql( sql, locks, keyColumnNames );
}