querytranslatorimpl.java

一个Java持久层类库

	private HqlSqlWalker getWalker() {
		return sqlAst.getWalker();
	}

	/**
	 * Types of the return values of an <tt>iterate()</tt> style query.
	 *
	 * @return an array of <tt>Type</tt>s.
	 */
	public Type[] getReturnTypes() {
		errorIfDML();
		return getWalker().getReturnTypes();
	}

	public String[] getReturnAliases() {
		errorIfDML();
		return getWalker().getReturnAliases();
	}

	public String[][] getColumnNames() {
		errorIfDML();
		return getWalker().getSelectClause().getColumnNames();
	}

	public Set getQuerySpaces() {
		return getWalker().getQuerySpaces();
	}

	public List list(SessionImplementor session, QueryParameters queryParameters)
			throws HibernateException {
		// Delegate to the QueryLoader...
		errorIfDML();
		QueryNode query = ( QueryNode ) sqlAst;
		boolean hasLimit = queryParameters.getRowSelection() != null && queryParameters.getRowSelection().definesLimits();
		boolean needsDistincting = ( query.getSelectClause().isDistinct() || hasLimit ) && containsCollectionFetches();

		QueryParameters queryParametersToUse;
		if ( hasLimit && containsCollectionFetches() ) {
			log.warn( "firstResult/maxResults specified with collection fetch; applying in memory!" );
			RowSelection selection = new RowSelection();
			selection.setFetchSize( queryParameters.getRowSelection().getFetchSize() );
			selection.setTimeout( queryParameters.getRowSelection().getTimeout() );
			queryParametersToUse = queryParameters.createCopyUsing( selection );
		}
		else {
			queryParametersToUse = queryParameters;
		}

		List results = queryLoader.list( session, queryParametersToUse );

		if ( needsDistincting ) {
			int includedCount = -1;
			// NOTE : firstRow is zero-based
			int first = !hasLimit || queryParameters.getRowSelection().getFirstRow() == null
						? 0
						: queryParameters.getRowSelection().getFirstRow().intValue();
			int max = !hasLimit || queryParameters.getRowSelection().getMaxRows() == null
						? -1
						: queryParameters.getRowSelection().getMaxRows().intValue();
			int size = results.size();
			List tmp = new ArrayList();
			IdentitySet distinction = new IdentitySet();
			for ( int i = 0; i < size; i++ ) {
				final Object result = results.get( i );
				if ( !distinction.add( result ) ) {
					continue;
				}
				includedCount++;
				if ( includedCount < first ) {
					continue;
				}
				tmp.add( result );
				// NOTE : ( max - 1 ) because first is zero-based while max is not...
				if ( max >= 0 && ( includedCount - first ) >= ( max - 1 ) ) {
					break;
				}
			}
			results = tmp;
		}

		return results;
	}

	/**
	 * Return the query results as an iterator
	 */
	public Iterator iterate(QueryParameters queryParameters, EventSource session)
			throws HibernateException {
		// Delegate to the QueryLoader...
		errorIfDML();
		return queryLoader.iterate( queryParameters, session );
	}

	/**
	 * Return the query results, as an instance of <tt>ScrollableResults</tt>
	 */
	public ScrollableResults scroll(QueryParameters queryParameters, SessionImplementor session)
			throws HibernateException {
		// Delegate to the QueryLoader...
		errorIfDML();
		return queryLoader.scroll( queryParameters, session );
	}

	public int executeUpdate(QueryParameters queryParameters, SessionImplementor session)
			throws HibernateException {
		errorIfSelect();
		return statementExecutor.execute( queryParameters, session );
	}

	/**
	 * The SQL query string to be called; implemented by all subclasses
	 */
	public String getSQLString() {
		return sql;
	}

	public List collectSqlStrings() {
		ArrayList list = new ArrayList();
		if ( isManipulationStatement() ) {
			String[] sqlStatements = statementExecutor.getSqlStatements();
			for ( int i = 0; i < sqlStatements.length; i++ ) {
				list.add( sqlStatements[i] );
			}
		}
		else {
			list.add( sql );
		}
		return list;
	}

	// -- Package local methods for the QueryLoader delegate --

	public boolean isShallowQuery() {
		return shallowQuery;
	}

	public String getQueryString() {
		return hql;
	}

	public Map getEnabledFilters() {
		return enabledFilters;
	}

	public int[] getNamedParameterLocs(String name) {
		return getWalker().getNamedParameterLocations( name );
	}

	public boolean containsCollectionFetches() {
		errorIfDML();
		List collectionFetches = ( ( QueryNode ) sqlAst ).getFromClause().getCollectionFetches();
		return collectionFetches != null && collectionFetches.size() > 0;
	}

	public boolean isManipulationStatement() {
		return sqlAst.needsExecutor();
	}

	public void validateScrollability() throws HibernateException {
		// Impl Note: allows multiple collection fetches as long as the
		// entire fecthed graph still "points back" to a single
		// root entity for return

		errorIfDML();

		QueryNode query = ( QueryNode ) sqlAst;

		// If there are no collection fetches, then no further checks are needed
		List collectionFetches = query.getFromClause().getCollectionFetches();
		if ( collectionFetches.isEmpty() ) {
			return;
		}

		// A shallow query is ok (although technically there should be no fetching here...)
		if ( isShallowQuery() ) {
			return;
		}

		// Otherwise, we have a non-scalar select with defined collection fetch(es).
		// Make sure that there is only a single root entity in the return (no tuples)
		if ( getReturnTypes().length > 1 ) {
			throw new HibernateException( "cannot scroll with collection fetches and returned tuples" );
		}

		FromElement owner = null;
		Iterator itr = query.getSelectClause().getFromElementsForLoad().iterator();
		while ( itr.hasNext() ) {
			// should be the first, but just to be safe...
			final FromElement fromElement = ( FromElement ) itr.next();
			if ( fromElement.getOrigin() == null ) {
				owner = fromElement;
				break;
			}
		}

		if ( owner == null ) {
			throw new HibernateException( "unable to locate collection fetch(es) owner for scrollability checks" );
		}

		// This is not strictly true.  We actually just need to make sure that
		// it is ordered by root-entity PK and that that order-by comes before
		// any non-root-entity ordering...

		AST primaryOrdering = query.getOrderByClause().getFirstChild();
		if ( primaryOrdering != null ) {
			// TODO : this is a bit dodgy, come up with a better way to check this (plus see above comment)
			String [] idColNames = owner.getQueryable().getIdentifierColumnNames();
			String expectedPrimaryOrderSeq = StringHelper.join(
			        ", ",
			        StringHelper.qualify( owner.getTableAlias(), idColNames )
			);
			if (  !primaryOrdering.getText().startsWith( expectedPrimaryOrderSeq ) ) {
				throw new HibernateException( "cannot scroll results with collection fetches which are not ordered primarily by the root entity's PK" );
			}
		}
	}

	private StatementExecutor buildAppropriateStatementExecutor(HqlSqlWalker walker) {
		Statement statement = ( Statement ) walker.getAST();
		if ( walker.getStatementType() == HqlSqlTokenTypes.DELETE ) {
			FromElement fromElement = walker.getFinalFromClause().getFromElement();
			Queryable persister = fromElement.getQueryable();
			if ( persister.isMultiTable() ) {
				return new MultiTableDeleteExecutor( walker );
			}
			else {
				return new BasicExecutor( walker, persister );
			}
		}
		else if ( walker.getStatementType() == HqlSqlTokenTypes.UPDATE ) {
			FromElement fromElement = walker.getFinalFromClause().getFromElement();
			Queryable persister = fromElement.getQueryable();
			if ( persister.isMultiTable() ) {
				// even here, if only properties mapped to the "base table" are referenced
				// in the set and where clauses, this could be handled by the BasicDelegate.
				// TODO : decide if it is better performance-wise to perform that check, or to simply use the MultiTableUpdateDelegate
				return new MultiTableUpdateExecutor( walker );
			}
			else {
				return new BasicExecutor( walker, persister );
			}
		}
		else if ( walker.getStatementType() == HqlSqlTokenTypes.INSERT ) {
			return new BasicExecutor( walker, ( ( InsertStatement ) statement ).getIntoClause().getQueryable() );
		}
		else {
			throw new QueryException( "Unexpected statement type" );
		}
	}

	public ParameterTranslations getParameterTranslations() {
		if ( paramTranslations == null ) {
			paramTranslations = new ParameterTranslationsImpl( getWalker().getParameters() );
		}
		return paramTranslations;
	}

	public static class JavaConstantConverter implements NodeTraverser.VisitationStrategy {
		private AST dotRoot;
		public void visit(AST node) {
			if ( dotRoot != null ) {
				// we are already processing a dot-structure
				if ( ASTUtil.isSubtreeChild( dotRoot, node ) ) {
					// igndore it...
					return;
				}
				else {
					// we are now at a new tree level
					dotRoot = null;
				}
			}

			if ( dotRoot == null && node.getType() == HqlTokenTypes.DOT ) {
				dotRoot = node;
				handleDotStructure( dotRoot );
			}
		}
		private void handleDotStructure(AST dotStructureRoot) {
			String expression = ASTUtil.getPathText( dotStructureRoot );
			Object constant = ReflectHelper.getConstantValue( expression );
			if ( constant != null ) {
				dotStructureRoot.setFirstChild( null );
				dotStructureRoot.setType( HqlTokenTypes.JAVA_CONSTANT );
				dotStructureRoot.setText( expression );
			}
		}
	}
}