abstractentityloader.java

用Java实现的23个常用设计模式源代码

//$Id: AbstractEntityLoader.java,v 1.6.2.17 2003/11/28 02:28:39 maxcsaucdk Exp $
package net.sf.hibernate.loader;

import java.io.Serializable;
import java.util.Iterator;
import java.util.List;

import net.sf.hibernate.AssertionFailure;
import net.sf.hibernate.LockMode;
import net.sf.hibernate.MappingException;
import net.sf.hibernate.collection.CollectionPersister;
import net.sf.hibernate.collection.QueryableCollection;
import net.sf.hibernate.engine.SessionFactoryImplementor;
import net.sf.hibernate.persister.Loadable;
import net.sf.hibernate.sql.JoinFragment;
import net.sf.hibernate.sql.Select;
import net.sf.hibernate.type.Type;
import net.sf.hibernate.util.ArrayHelper;
import net.sf.hibernate.util.StringHelper;

/**
 * Abstract superclass for entity loaders that use outer joins
 * 
 * @see CriteriaLoader
 * @see EntityLoader
 * @author Gavin King
 */
public abstract class AbstractEntityLoader extends OuterJoinLoader {

	private final Loadable persister;
	private CollectionPersister collectionPersister;
	private int collectionOwner;
	private String alias;
	
	public AbstractEntityLoader(Loadable persister, SessionFactoryImplementor factory) {
		super( factory.getDialect() );
		this.persister = persister;
		alias = generateRootAlias( persister.getClassName() );		
	}
	
	protected final void renderStatement(String condition, SessionFactoryImplementor factory) throws MappingException {
		renderStatement(condition, StringHelper.EMPTY_STRING, factory);
	}
	
	protected final void addAllToPropertySpaces(Serializable[] spaces) {
		for ( int i=0; i<spaces.length; i++ ) addToPropertySpaces( spaces[i] );
	}
	
	protected void addToPropertySpaces(Serializable space) {
		throw new AssertionFailure("only criteria queries need to autoflush");
	}
	
	private int toOwner(OuterJoinableAssociation oj, int joins, boolean dontIgnore) {
		if (dontIgnore) {
			return (oj.owner==-1) ? joins : oj.owner; //TODO: UGLY AS SIN!
		}
		else {
			return -1;
		}
	}
	
	protected final void renderStatement(String condition, String orderBy, SessionFactoryImplementor factory) throws MappingException {

		List associations = walkTree(persister, alias, factory);
		
		int joins=countClassPersisters(associations);

		collectionOwner = -1; //if no collection found
		classPersisters = new Loadable[joins+1];
		owners = new int[joins+1];
		lockModeArray = createLockModeArray(joins+1, LockMode.NONE);
		int i=0;
		Iterator iter = associations.iterator();
		while ( iter.hasNext() ) {
			OuterJoinableAssociation oj = (OuterJoinableAssociation) iter.next(); 
			Object subpersister = oj.joinable;
			if (subpersister instanceof Loadable) {
				classPersisters[i] = (Loadable) subpersister;
				owners[i] = toOwner(oj, joins, oj.isOneToOne);
				if (oj.joinType==JoinFragment.INNER_JOIN) addAllToPropertySpaces( classPersisters[i].getPropertySpaces() );
				i++;
			}
			else {
				QueryableCollection collPersister = (QueryableCollection) subpersister;
				if (oj.joinType==JoinFragment.LEFT_OUTER_JOIN) { //supress initialization of collections with a where condition!
					collectionPersister = collPersister;
					collectionOwner = toOwner(oj, joins, true);
				}
				else {
					addToPropertySpaces( collPersister.getCollectionSpace() );
				}
				if ( collPersister.isOneToMany() ) {
					classPersisters[i++] = collPersister.getElementPersister();
				}
			}
		}
		classPersisters[joins] = persister;
		owners[joins] = -1;
		
		if ( ArrayHelper.isAllNegative(owners) ) owners = null;

		suffixes = generateSuffixes(joins+1);
		
		JoinFragment ojf = mergeOuterJoins(associations);

		sql = new Select()
			.setSelectClause(
				persister.joinSelectFragment( alias, suffixes[joins] ) +
				selectString(associations, factory)
			)
			.setFromClause( 
				persister.fromTableFragment(alias) +
				persister.fromJoinFragment(alias, true, true)
			)
			.setWhereClause(condition)
			.setOuterJoins(
				ojf.toFromFragmentString(),
				ojf.toWhereFragmentString() + getWhereFragment()
			)
			.setOrderByClause(orderBy)
			.toStatementString();
		
	}
	
	/**
	 * Don't bother with the discriminator, unless overridded by subclass
	 */
	protected String getWhereFragment() throws MappingException {
		return persister.whereJoinFragment(alias, true, true);
	}

	protected final Loadable getPersister() {
		return persister;
	}

	protected final void setAlias(String alias) {
		this.alias = alias;
	}

	protected final String getAlias() {
		return alias;
	}

	protected final CollectionPersister getCollectionPersister() {
		return collectionPersister;
	}

	protected final int getCollectionOwner() {
		return collectionOwner;
	}

	protected boolean isJoinedFetchEnabled(
		Type type,
		boolean mappingDefault,
		String path,
		String table,
		String[] foreignKeyColumns) {
		
		return mappingDefault;
	}

	public String toString() {
		return getClass().getName() + " for " + getPersister().getClassName();
	}
}