hibernate source code 阅读一

上一篇文章我试着在eclipse中配置了一个简单hibernate实例，下面我们通过这个简单的例子来看看hibernate源码中都做了些什么：

import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;public class  SimpleTest{public static void main(String[] args) {SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();Session session = sessionFactory.getCurrentSession();Transaction tx = session.beginTransaction();Tparam param = new Tparam();param.setFcode(12345678l);param.setFremark("hibernate test");session.save(param);tx.commit();}}

在Configuration类中调用configure()方法，目的是为了解析hibernate.cfg.xml文件中的信息：

/** * Use the mappings and properties specified in an application * resource named <tt>hibernate.cfg.xml</tt>. */public Configuration configure() throws HibernateException {configure( "/hibernate.cfg.xml" );return this;}

通过资源文件获取一个输入流，再通过这个输入流和资源文件进行具体解析

/** * Use the mappings and properties specified in the given application * resource. The format of the resource is defined in * <tt>hibernate-configuration-3.0.dtd</tt>. * <p/> * The resource is found via <tt>getConfigurationInputStream(resource)</tt>. */public Configuration configure(String resource) throws HibernateException {log.info( "configuring from resource: " + resource );InputStream stream = getConfigurationInputStream( resource );return doConfigure( stream, resource );}

/** * Get the configuration file as an <tt>InputStream</tt>. Might be overridden * by subclasses to allow the configuration to be located by some arbitrary * mechanism. */protected InputStream getConfigurationInputStream(String resource) throws HibernateException {log.info( "Configuration resource: " + resource );return ConfigHelper.getResourceAsStream( resource );}

关于这块具体是如何得到这个流，我会专门用一篇文章来讲解

public static InputStream getResourceAsStream(String resource) {String stripped = resource.startsWith("/") ?resource.substring(1) : resource;InputStream stream = null;ClassLoader classLoader = Thread.currentThread().getContextClassLoader();if (classLoader!=null) {stream = classLoader.getResourceAsStream( stripped );}if ( stream == null ) {stream = Environment.class.getResourceAsStream( resource );}if ( stream == null ) {stream = Environment.class.getClassLoader().getResourceAsStream( stripped );}if ( stream == null ) {throw new HibernateException( resource + " not found" );}return stream;}

/** * Use the mappings and properties specified in the given application * resource. The format of the resource is defined in * <tt>hibernate-configuration-3.0.dtd</tt>. * * @param stream   Inputstream to be read from * @param resourceName The name to use in warning/error messages * @return A configuration configured via the stream * @throws HibernateException */protected Configuration doConfigure(InputStream stream, String resourceName) throws HibernateException {org.dom4j.Document doc;try {List errors = new ArrayList();doc = xmlHelper.createSAXReader( resourceName, errors, entityResolver ).read( new InputSource( stream ) );if ( errors.size() != 0 ) {throw new MappingException("invalid configuration",(Throwable) errors.get( 0 ));}}catch (DocumentException e) {throw new HibernateException("Could not parse configuration: " + resourceName,e);}finally {try {stream.close();}catch (IOException ioe) {log.warn( "could not close input stream for: " + resourceName, ioe );}}return doConfigure( doc );}

我们可以看到，最终解析的数据都存放到properties类中（java.util.Properties继承java.util.Hashtable）

protected Configuration doConfigure(org.dom4j.Document doc) throws HibernateException {Element sfNode = doc.getRootElement().element( "session-factory" );String name = sfNode.attributeValue( "name" );if ( name != null ) {properties.setProperty( Environment.SESSION_FACTORY_NAME, name );}addProperties( sfNode );parseSessionFactory( sfNode, name );Element secNode = doc.getRootElement().element( "security" );if ( secNode != null ) {parseSecurity( secNode );}log.info( "Configured SessionFactory: " + name );log.debug( "properties: " + properties );return this;}

private void addProperties(Element parent) {Iterator iter = parent.elementIterator( "property" );while ( iter.hasNext() ) {Element node = (Element) iter.next();String name = node.attributeValue( "name" );String value = node.getText().trim();log.debug( name + "=" + value );properties.setProperty( name, value );if ( !name.startsWith( "hibernate" ) ) {properties.setProperty( "hibernate." + name, value );}}Environment.verifyProperties( properties );}

解析完hibernate.cfg.xml文件后，我们再来看看buildSessionFactory()方法：

这里我们可以看到，上面针对hibernate.cfg.xml文件解析完了之后在这里用到了copy.putAll( propertites )。

/** * Instantiate a new <tt>SessionFactory</tt>, using the properties and * mappings in this configuration. The <tt>SessionFactory</tt> will be * immutable, so changes made to the <tt>Configuration</tt> after * building the <tt>SessionFactory</tt> will not affect it. * * @return a new factory for <tt>Session</tt>s * @see org.hibernate.SessionFactory */public SessionFactory buildSessionFactory() throws HibernateException {log.debug( "Preparing to build session factory with filters : " + filterDefinitions );secondPassCompile();validate();Environment.verifyProperties( properties );Properties copy = new Properties();copy.putAll( properties );PropertiesHelper.resolvePlaceHolders( copy );Settings settings = buildSettings( copy );return new SessionFactoryImpl(this,mapping,settings,getInitializedEventListeners());}

SessionFactoryImpl构造方法虽然些了很多东西，但是我们没必要每一行都看，我们着重看看下面这一行

currentSessionContext = buildCurrentSessionContext();因为getCurrentSession()就是通过这里构建出来的实现类对SessionFactory接口中getCurrentSession()方法进行实现

public SessionFactoryImpl(Configuration cfg,        Mapping mapping,        Settings settings,        EventListeners listeners)throws HibernateException {log.info("building session factory");this.properties = new Properties();this.properties.putAll( cfg.getProperties() );this.interceptor = cfg.getInterceptor();this.settings = settings;this.sqlFunctionRegistry = new SQLFunctionRegistry(settings.getDialect(), cfg.getSqlFunctions());        this.eventListeners = listeners;        this.filters = new HashMap();this.filters.putAll( cfg.getFilterDefinitions() );if ( log.isDebugEnabled() ) {log.debug("Session factory constructed with filter configurations : " + filters);}if ( log.isDebugEnabled() ) {log.debug("instantiating session factory with properties: " + properties);}// Cachessettings.getCacheProvider().start( properties );//Generators:identifierGenerators = new HashMap();Iterator classes = cfg.getClassMappings();while ( classes.hasNext() ) {PersistentClass model = (PersistentClass) classes.next();if ( !model.isInherited() ) {IdentifierGenerator generator = model.getIdentifier().createIdentifierGenerator(settings.getDialect(),        settings.getDefaultCatalogName(),        settings.getDefaultSchemaName(),        (RootClass) model);identifierGenerators.put( model.getEntityName(), generator );}}//Persisters:Map caches = new HashMap();entityPersisters = new HashMap();Map classMeta = new HashMap();classes = cfg.getClassMappings();while ( classes.hasNext() ) {PersistentClass model = (PersistentClass) classes.next();model.prepareTemporaryTables( mapping, settings.getDialect() );String cacheRegion = model.getRootClass().getCacheRegionName();CacheConcurrencyStrategy cache = (CacheConcurrencyStrategy) caches.get(cacheRegion);if (cache==null) {cache = CacheFactory.createCache(model.getCacheConcurrencyStrategy(),        cacheRegion,        model.isMutable(),        settings,        properties);if (cache!=null) {caches.put(cacheRegion, cache);allCacheRegions.put( cache.getRegionName(), cache.getCache() );}}EntityPersister cp = PersisterFactory.createClassPersister(model, cache, this, mapping);if ( cache != null && cache.getCache() instanceof OptimisticCache ) {( ( OptimisticCache ) cache.getCache() ).setSource( cp );}entityPersisters.put( model.getEntityName(), cp );classMeta.put( model.getEntityName(), cp.getClassMetadata() );}classMetadata = Collections.unmodifiableMap(classMeta);Map tmpEntityToCollectionRoleMap = new HashMap();collectionPersisters = new HashMap();Iterator collections = cfg.getCollectionMappings();while ( collections.hasNext() ) {Collection model = (Collection) collections.next();CacheConcurrencyStrategy cache = CacheFactory.createCache(model.getCacheConcurrencyStrategy(),    model.getCacheRegionName(),    model.isMutable(),    settings,    properties);if ( cache != null ) {allCacheRegions.put( cache.getRegionName(), cache.getCache() );}CollectionPersister persister = PersisterFactory.createCollectionPersister(cfg, model, cache, this);collectionPersisters.put( model.getRole(), persister.getCollectionMetadata() );Type indexType = persister.getIndexType();if ( indexType != null && indexType.isAssociationType() && !indexType.isAnyType() ) {String entityName = ( ( AssociationType ) indexType ).getAssociatedEntityName( this );Set roles = ( Set ) tmpEntityToCollectionRoleMap.get( entityName );if ( roles == null ) {roles = new HashSet();tmpEntityToCollectionRoleMap.put( entityName, roles );}roles.add( persister.getRole() );}Type elementType = persister.getElementType();if ( elementType.isAssociationType() && !elementType.isAnyType() ) {String entityName = ( ( AssociationType ) elementType ).getAssociatedEntityName( this );Set roles = ( Set ) tmpEntityToCollectionRoleMap.get( entityName );if ( roles == null ) {roles = new HashSet();tmpEntityToCollectionRoleMap.put( entityName, roles );}roles.add( persister.getRole() );}}collectionMetadata = Collections.unmodifiableMap(collectionPersisters);Iterator itr = tmpEntityToCollectionRoleMap.entrySet().iterator();while ( itr.hasNext() ) {final Map.Entry entry = ( Map.Entry ) itr.next();entry.setValue( Collections.unmodifiableSet( ( Set ) entry.getValue() ) );}collectionRolesByEntityParticipant = Collections.unmodifiableMap( tmpEntityToCollectionRoleMap );//Named Queries:namedQueries = new HashMap( cfg.getNamedQueries() );namedSqlQueries = new HashMap( cfg.getNamedSQLQueries() );sqlResultSetMappings = new HashMap( cfg.getSqlResultSetMappings() );imports = new HashMap( cfg.getImports() );// after *all* persisters and named queries are registeredIterator iter = entityPersisters.values().iterator();while ( iter.hasNext() ) {( (EntityPersister) iter.next() ).postInstantiate();}iter = collectionPersisters.values().iterator();while ( iter.hasNext() ) {( (CollectionPersister) iter.next() ).postInstantiate();}//JNDI + Serialization:name = settings.getSessionFactoryName();try {uuid = (String) UUID_GENERATOR.generate(null, null);}catch (Exception e) {throw new AssertionFailure("Could not generate UUID");}SessionFactoryObjectFactory.addInstance(uuid, name, this, properties);log.debug("instantiated session factory");if ( settings.isAutoCreateSchema() ) {new SchemaExport( cfg, settings ).create( false, true );}if ( settings.isAutoUpdateSchema() ) {new SchemaUpdate( cfg, settings ).execute( false, true );}if ( settings.isAutoValidateSchema() ) {new SchemaValidator( cfg, settings ).validate();}if ( settings.isAutoDropSchema() ) {schemaExport = new SchemaExport( cfg, settings );}if ( settings.getTransactionManagerLookup()!=null ) {log.debug("obtaining JTA TransactionManager");transactionManager = settings.getTransactionManagerLookup().getTransactionManager(properties);}else {if ( settings.getTransactionFactory().isTransactionManagerRequired() ) {throw new HibernateException("The chosen transaction strategy requires access to the JTA TransactionManager");}transactionManager = null;}currentSessionContext = buildCurrentSessionContext();if ( settings.isQueryCacheEnabled() ) {updateTimestampsCache = new UpdateTimestampsCache(settings, properties);queryCache = settings.getQueryCacheFactory()        .getQueryCache(null, updateTimestampsCache, settings, properties);queryCaches = new HashMap();allCacheRegions.put( updateTimestampsCache.getRegionName(), updateTimestampsCache.getCache() );allCacheRegions.put( queryCache.getRegionName(), queryCache.getCache() );}else {updateTimestampsCache = null;queryCache = null;queryCaches = null;}//checking for named queriesif ( settings.isNamedQueryStartupCheckingEnabled() ) {Map errors = checkNamedQueries();if ( !errors.isEmpty() ) {Set keys = errors.keySet();StringBuffer failingQueries = new StringBuffer( "Errors in named queries: " );for ( Iterator iterator = keys.iterator() ; iterator.hasNext() ; ) {String queryName = ( String ) iterator.next();HibernateException e = ( HibernateException ) errors.get( queryName );failingQueries.append( queryName );if ( iterator.hasNext() ) {failingQueries.append( ", " );}log.error( "Error in named query: " + queryName, e );}throw new HibernateException( failingQueries.toString() );}}//statsgetStatistics().setStatisticsEnabled( settings.isStatisticsEnabled() );// EntityNotFoundDelegateEntityNotFoundDelegate entityNotFoundDelegate = cfg.getEntityNotFoundDelegate();if ( entityNotFoundDelegate == null ) {entityNotFoundDelegate = new EntityNotFoundDelegate() {public void handleEntityNotFound(String entityName, Serializable id) {throw new ObjectNotFoundException( id, entityName );}};}this.entityNotFoundDelegate = entityNotFoundDelegate;}

这里面代码很多，有些我也不太知道做了些什么，我抓住的关键点是这句：EntityPersister cp = PersisterFactory.createClassPersister(model, cache, this, mapping);

这句到底做了些什么我们往里面看：

public static EntityPersister createClassPersister(PersistentClass model, CacheConcurrencyStrategy cache, SessionFactoryImplementor factory,Mapping cfg)throws HibernateException {Class persisterClass = model.getEntityPersisterClass();if (persisterClass==null || persisterClass==SingleTableEntityPersister.class) {return new SingleTableEntityPersister(model, cache, factory, cfg);}else if (persisterClass==JoinedSubclassEntityPersister.class) {return new JoinedSubclassEntityPersister(model, cache, factory, cfg);}else if (persisterClass==UnionSubclassEntityPersister.class) {return new UnionSubclassEntityPersister(model, cache, factory, cfg);}else {return create(persisterClass, model, cache, factory, cfg);}}

我们现在操作的单表，那么我们进入new SingleTableEntityPersister(model, cache, factory, cfg);这句看看里面执行了什么：

public SingleTableEntityPersister(final PersistentClass persistentClass, final CacheConcurrencyStrategy cache,final SessionFactoryImplementor factory,final Mapping mapping)throws HibernateException {super(persistentClass, cache, factory);// CLASS + TABLEjoinSpan = persistentClass.getJoinClosureSpan()+1;qualifiedTableNames = new String[joinSpan];isInverseTable = new boolean[joinSpan];isNullableTable = new boolean[joinSpan];keyColumnNames = new String[joinSpan][];final Table table = persistentClass.getRootTable();qualifiedTableNames[0] = table.getQualifiedName( factory.getDialect(), factory.getSettings().getDefaultCatalogName(), factory.getSettings().getDefaultSchemaName() );isInverseTable[0] = false;isNullableTable[0] = false;keyColumnNames[0] = getIdentifierColumnNames();cascadeDeleteEnabled = new boolean[joinSpan];// Custom sqlcustomSQLInsert = new String[joinSpan];customSQLUpdate = new String[joinSpan];customSQLDelete = new String[joinSpan];insertCallable = new boolean[joinSpan];updateCallable = new boolean[joinSpan];deleteCallable = new boolean[joinSpan];insertResultCheckStyles = new ExecuteUpdateResultCheckStyle[joinSpan];updateResultCheckStyles = new ExecuteUpdateResultCheckStyle[joinSpan];deleteResultCheckStyles = new ExecuteUpdateResultCheckStyle[joinSpan];customSQLInsert[0] = persistentClass.getCustomSQLInsert();insertCallable[0] = customSQLInsert[0] != null && persistentClass.isCustomInsertCallable();insertResultCheckStyles[0] = persistentClass.getCustomSQLInsertCheckStyle() == null  ? ExecuteUpdateResultCheckStyle.determineDefault( customSQLInsert[0], insertCallable[0] )  : persistentClass.getCustomSQLInsertCheckStyle();customSQLUpdate[0] = persistentClass.getCustomSQLUpdate();updateCallable[0] = customSQLUpdate[0] != null && persistentClass.isCustomUpdateCallable();updateResultCheckStyles[0] = persistentClass.getCustomSQLUpdateCheckStyle() == null  ? ExecuteUpdateResultCheckStyle.determineDefault( customSQLUpdate[0], updateCallable[0] )  : persistentClass.getCustomSQLUpdateCheckStyle();customSQLDelete[0] = persistentClass.getCustomSQLDelete();deleteCallable[0] = customSQLDelete[0] != null && persistentClass.isCustomDeleteCallable();deleteResultCheckStyles[0] = persistentClass.getCustomSQLDeleteCheckStyle() == null  ? ExecuteUpdateResultCheckStyle.determineDefault( customSQLDelete[0], deleteCallable[0] )  : persistentClass.getCustomSQLDeleteCheckStyle();// JOINSIterator joinIter = persistentClass.getJoinClosureIterator();int j = 1;while ( joinIter.hasNext() ) {Join join = (Join) joinIter.next();qualifiedTableNames[j] = join.getTable().getQualifiedName( factory.getDialect(), factory.getSettings().getDefaultCatalogName(), factory.getSettings().getDefaultSchemaName() );isInverseTable[j] = join.isInverse();isNullableTable[j] = join.isOptional();cascadeDeleteEnabled[j] = join.getKey().isCascadeDeleteEnabled() && factory.getDialect().supportsCascadeDelete();customSQLInsert[j] = join.getCustomSQLInsert();insertCallable[j] = customSQLInsert[j] != null && join.isCustomInsertCallable();insertResultCheckStyles[j] = join.getCustomSQLInsertCheckStyle() == null                              ? ExecuteUpdateResultCheckStyle.determineDefault( customSQLInsert[j], insertCallable[j] )                                  : join.getCustomSQLInsertCheckStyle();customSQLUpdate[j] = join.getCustomSQLUpdate();updateCallable[j] = customSQLUpdate[j] != null && join.isCustomUpdateCallable();updateResultCheckStyles[j] = join.getCustomSQLUpdateCheckStyle() == null                              ? ExecuteUpdateResultCheckStyle.determineDefault( customSQLUpdate[j], updateCallable[j] )                                  : join.getCustomSQLUpdateCheckStyle();customSQLDelete[j] = join.getCustomSQLDelete();deleteCallable[j] = customSQLDelete[j] != null && join.isCustomDeleteCallable();deleteResultCheckStyles[j] = join.getCustomSQLDeleteCheckStyle() == null                              ? ExecuteUpdateResultCheckStyle.determineDefault( customSQLDelete[j], deleteCallable[j] )                                  : join.getCustomSQLDeleteCheckStyle();Iterator iter = join.getKey().getColumnIterator();keyColumnNames[j] = new String[ join.getKey().getColumnSpan() ];int i = 0;while ( iter.hasNext() ) {Column col = (Column) iter.next();keyColumnNames[j][i++] = col.getQuotedName( factory.getDialect() );}j++;}constraintOrderedTableNames = new String[qualifiedTableNames.length];constraintOrderedKeyColumnNames = new String[qualifiedTableNames.length][];for ( int i = qualifiedTableNames.length - 1, position = 0; i >= 0; i--, position++ ) {constraintOrderedTableNames[position] = qualifiedTableNames[i];constraintOrderedKeyColumnNames[position] = keyColumnNames[i];}spaces = ArrayHelper.join(qualifiedTableNames, ArrayHelper.toStringArray( persistentClass.getSynchronizedTables() ));final boolean lazyAvailable = isInstrumented(EntityMode.POJO);boolean hasDeferred = false;ArrayList subclassTables = new ArrayList();ArrayList joinKeyColumns = new ArrayList();ArrayList isConcretes = new ArrayList();ArrayList isDeferreds = new ArrayList();ArrayList isInverses = new ArrayList();ArrayList isNullables = new ArrayList();ArrayList isLazies = new ArrayList();subclassTables.add( qualifiedTableNames[0] );joinKeyColumns.add( getIdentifierColumnNames() );isConcretes.add(Boolean.TRUE);isDeferreds.add(Boolean.FALSE);isInverses.add(Boolean.FALSE);isNullables.add(Boolean.FALSE);isLazies.add(Boolean.FALSE);joinIter = persistentClass.getSubclassJoinClosureIterator();while ( joinIter.hasNext() ) {Join join = (Join) joinIter.next();isConcretes.add( new Boolean( persistentClass.isClassOrSuperclassJoin(join) ) );isDeferreds.add( new Boolean( join.isSequentialSelect() ) );isInverses.add( new Boolean( join.isInverse() ) );isNullables.add( new Boolean( join.isOptional() ) );isLazies.add( new Boolean( lazyAvailable && join.isLazy() ) );if ( join.isSequentialSelect() && !persistentClass.isClassOrSuperclassJoin(join) ) hasDeferred = true;subclassTables.add( join.getTable().getQualifiedName( factory.getDialect(), factory.getSettings().getDefaultCatalogName(), factory.getSettings().getDefaultSchemaName() ) );Iterator iter = join.getKey().getColumnIterator();String[] keyCols = new String[ join.getKey().getColumnSpan() ];int i = 0;while ( iter.hasNext() ) {Column col = (Column) iter.next();keyCols[i++] = col.getQuotedName( factory.getDialect() );}joinKeyColumns.add(keyCols);}subclassTableSequentialSelect = ArrayHelper.toBooleanArray(isDeferreds);subclassTableNameClosure = ArrayHelper.toStringArray(subclassTables);subclassTableIsLazyClosure = ArrayHelper.toBooleanArray(isLazies);subclassTableKeyColumnClosure = ArrayHelper.to2DStringArray(joinKeyColumns);isClassOrSuperclassTable = ArrayHelper.toBooleanArray(isConcretes);isInverseSubclassTable = ArrayHelper.toBooleanArray(isInverses);isNullableSubclassTable = ArrayHelper.toBooleanArray(isNullables);hasSequentialSelects = hasDeferred;// DISCRIMINATORfinal Object discriminatorValue;if ( persistentClass.isPolymorphic() ) {Value discrimValue = persistentClass.getDiscriminator();if (discrimValue==null) {throw new MappingException("discriminator mapping required for single table polymorphic persistence");}forceDiscriminator = persistentClass.isForceDiscriminator();Selectable selectable = (Selectable) discrimValue.getColumnIterator().next();if ( discrimValue.hasFormula() ) {Formula formula = (Formula) selectable;discriminatorFormula = formula.getFormula();discriminatorFormulaTemplate = formula.getTemplate( factory.getDialect(), factory.getSqlFunctionRegistry() );discriminatorColumnName = null;discriminatorAlias = "clazz_";}else {Column column = (Column) selectable;discriminatorColumnName = column.getQuotedName( factory.getDialect() );discriminatorAlias = column.getAlias( factory.getDialect(), persistentClass.getRootTable() );discriminatorFormula = null;discriminatorFormulaTemplate = null;}discriminatorType = persistentClass.getDiscriminator().getType();if ( persistentClass.isDiscriminatorValueNull() ) {discriminatorValue = NULL_DISCRIMINATOR;discriminatorSQLValue = InFragment.NULL;discriminatorInsertable = false;}else if ( persistentClass.isDiscriminatorValueNotNull() ) {discriminatorValue = NOT_NULL_DISCRIMINATOR;discriminatorSQLValue = InFragment.NOT_NULL;discriminatorInsertable = false;}else {discriminatorInsertable = persistentClass.isDiscriminatorInsertable() && !discrimValue.hasFormula();try {DiscriminatorType dtype = (DiscriminatorType) discriminatorType;discriminatorValue = dtype.stringToObject( persistentClass.getDiscriminatorValue() );discriminatorSQLValue = dtype.objectToSQLString( discriminatorValue, factory.getDialect() );}catch (ClassCastException cce) {throw new MappingException("Illegal discriminator type: " + discriminatorType.getName() );}catch (Exception e) {throw new MappingException("Could not format discriminator value to SQL string", e);}}}else {forceDiscriminator = false;discriminatorInsertable = false;discriminatorColumnName = null;discriminatorAlias = null;discriminatorType = null;discriminatorValue = null;discriminatorSQLValue = null;discriminatorFormula = null;discriminatorFormulaTemplate = null;}// PROPERTIESpropertyTableNumbers = new int[ getPropertySpan() ];Iterator iter = persistentClass.getPropertyClosureIterator();int i=0;while( iter.hasNext() ) {Property prop = (Property) iter.next();propertyTableNumbers[i++] = persistentClass.getJoinNumber(prop);}//TODO: code duplication with JoinedSubclassEntityPersisterArrayList columnJoinNumbers = new ArrayList();ArrayList formulaJoinedNumbers = new ArrayList();ArrayList propertyJoinNumbers = new ArrayList();iter = persistentClass.getSubclassPropertyClosureIterator();while ( iter.hasNext() ) {Property prop = (Property) iter.next();Integer join = new Integer( persistentClass.getJoinNumber(prop) );propertyJoinNumbers.add(join);//propertyTableNumbersByName.put( prop.getName(), join );propertyTableNumbersByNameAndSubclass.put( prop.getPersistentClass().getEntityName() + '.' + prop.getName(), join );Iterator citer = prop.getColumnIterator();while ( citer.hasNext() ) {Selectable thing = (Selectable) citer.next();if ( thing.isFormula() ) {formulaJoinedNumbers.add(join);}else {columnJoinNumbers.add(join);}}}subclassColumnTableNumberClosure = ArrayHelper.toIntArray(columnJoinNumbers);subclassFormulaTableNumberClosure = ArrayHelper.toIntArray(formulaJoinedNumbers);subclassPropertyTableNumberClosure = ArrayHelper.toIntArray(propertyJoinNumbers);int subclassSpan = persistentClass.getSubclassSpan() + 1;subclassClosure = new String[subclassSpan];subclassClosure[0] = getEntityName();if ( persistentClass.isPolymorphic() ) {subclassesByDiscriminatorValue.put( discriminatorValue, getEntityName() );}// SUBCLASSESif ( persistentClass.isPolymorphic() ) {iter = persistentClass.getSubclassIterator();int k=1;while ( iter.hasNext() ) {Subclass sc = (Subclass) iter.next();subclassClosure[k++] = sc.getEntityName();if ( sc.isDiscriminatorValueNull() ) {subclassesByDiscriminatorValue.put( NULL_DISCRIMINATOR, sc.getEntityName() );}else if ( sc.isDiscriminatorValueNotNull() ) {subclassesByDiscriminatorValue.put( NOT_NULL_DISCRIMINATOR, sc.getEntityName() );}else {try {DiscriminatorType dtype = (DiscriminatorType) discriminatorType;subclassesByDiscriminatorValue.put(dtype.stringToObject( sc.getDiscriminatorValue() ),sc.getEntityName());}catch (ClassCastException cce) {throw new MappingException("Illegal discriminator type: " + discriminatorType.getName() );}catch (Exception e) {throw new MappingException("Error parsing discriminator value", e);}}}}initLockers();initSubclassPropertyAliasesMap(persistentClass);postConstruct(mapping);}

上面代码中第一行是：super(persistentClass, cache, factory);

我们进去可以看到，配置文件中的很多属性和表名都会在这里进行解析并初始化以供后面拼接SQL语句使用：

public AbstractEntityPersister(final PersistentClass persistentClass,final CacheConcurrencyStrategy cache,final SessionFactoryImplementor factory)throws HibernateException {// moved up from AbstractEntityPersister ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~this.factory = factory;this.cache = cache;isLazyPropertiesCacheable = persistentClass.isLazyPropertiesCacheable();this.cacheEntryStructure = factory.getSettings().isStructuredCacheEntriesEnabled() ?(CacheEntryStructure) new StructuredCacheEntry(this) :(CacheEntryStructure) new UnstructuredCacheEntry();this.entityMetamodel = new EntityMetamodel( persistentClass, factory );if ( persistentClass.hasPojoRepresentation() ) {//TODO: this is currently specific to pojos, but need to be available for all entity-modesIterator iter = persistentClass.getSubclassIterator();while ( iter.hasNext() ) {PersistentClass pc = ( PersistentClass ) iter.next();entityNameBySubclass.put( pc.getMappedClass(), pc.getEntityName() );}}// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~int batch = persistentClass.getBatchSize();if ( batch == -1 ) {batch = factory.getSettings().getDefaultBatchFetchSize();}batchSize = batch;hasSubselectLoadableCollections = persistentClass.hasSubselectLoadableCollections();propertyMapping = new BasicEntityPropertyMapping( this );// IDENTIFIERidentifierColumnSpan = persistentClass.getIdentifier().getColumnSpan();rootTableKeyColumnNames = new String[identifierColumnSpan];identifierAliases = new String[identifierColumnSpan];rowIdName = persistentClass.getRootTable().getRowId();loaderName = persistentClass.getLoaderName();Iterator iter = persistentClass.getIdentifier().getColumnIterator();int i = 0;while ( iter.hasNext() ) {Column col = ( Column ) iter.next();rootTableKeyColumnNames[i] = col.getQuotedName( factory.getDialect() );identifierAliases[i] = col.getAlias( factory.getDialect(), persistentClass.getRootTable() );i++;}// VERSIONif ( persistentClass.isVersioned() ) {versionColumnName = ( ( Column ) persistentClass.getVersion().getColumnIterator().next() ).getQuotedName( factory.getDialect() );}else {versionColumnName = null;}//WHERE STRINGsqlWhereString = StringHelper.isNotEmpty( persistentClass.getWhere() ) ? "( " + persistentClass.getWhere() + ") " : null;sqlWhereStringTemplate = sqlWhereString == null ?null :Template.renderWhereStringTemplate( sqlWhereString, factory.getDialect(), factory.getSqlFunctionRegistry() );// PROPERTIESfinal boolean lazyAvailable = isInstrumented(EntityMode.POJO);int hydrateSpan = entityMetamodel.getPropertySpan();propertyColumnSpans = new int[hydrateSpan];propertySubclassNames = new String[hydrateSpan];propertyColumnAliases = new String[hydrateSpan][];propertyColumnNames = new String[hydrateSpan][];propertyColumnFormulaTemplates = new String[hydrateSpan][];propertyUniqueness = new boolean[hydrateSpan];propertySelectable = new boolean[hydrateSpan];propertyColumnUpdateable = new boolean[hydrateSpan][];propertyColumnInsertable = new boolean[hydrateSpan][];HashSet thisClassProperties = new HashSet();lazyProperties = new HashSet();ArrayList lazyNames = new ArrayList();ArrayList lazyNumbers = new ArrayList();ArrayList lazyTypes = new ArrayList();ArrayList lazyColAliases = new ArrayList();iter = persistentClass.getPropertyClosureIterator();i = 0;boolean foundFormula = false;while ( iter.hasNext() ) {Property prop = ( Property ) iter.next();thisClassProperties.add( prop );int span = prop.getColumnSpan();propertyColumnSpans[i] = span;propertySubclassNames[i] = prop.getPersistentClass().getEntityName();String[] colNames = new String[span];String[] colAliases = new String[span];String[] templates = new String[span];Iterator colIter = prop.getColumnIterator();int k = 0;while ( colIter.hasNext() ) {Selectable thing = ( Selectable ) colIter.next();colAliases[k] = thing.getAlias( factory.getDialect() , prop.getValue().getTable() );if ( thing.isFormula() ) {foundFormula = true;templates[k] = thing.getTemplate( factory.getDialect(), factory.getSqlFunctionRegistry() );}else {colNames[k] = thing.getTemplate( factory.getDialect(), factory.getSqlFunctionRegistry() );}k++;}propertyColumnNames[i] = colNames;propertyColumnFormulaTemplates[i] = templates;propertyColumnAliases[i] = colAliases;if ( lazyAvailable && prop.isLazy() ) {lazyProperties.add( prop.getName() );lazyNames.add( prop.getName() );lazyNumbers.add( new Integer( i ) );lazyTypes.add( prop.getValue().getType() );lazyColAliases.add( colAliases );}propertyColumnUpdateable[i] = prop.getValue().getColumnUpdateability();propertyColumnInsertable[i] = prop.getValue().getColumnInsertability();propertySelectable[i] = prop.isSelectable();propertyUniqueness[i] = prop.getValue().isAlternateUniqueKey();i++;}hasFormulaProperties = foundFormula;lazyPropertyColumnAliases = ArrayHelper.to2DStringArray( lazyColAliases );lazyPropertyNames = ArrayHelper.toStringArray( lazyNames );lazyPropertyNumbers = ArrayHelper.toIntArray( lazyNumbers );lazyPropertyTypes = ArrayHelper.toTypeArray( lazyTypes );// SUBCLASS PROPERTY CLOSUREArrayList columns = new ArrayList();ArrayList columnsLazy = new ArrayList();ArrayList aliases = new ArrayList();ArrayList formulas = new ArrayList();ArrayList formulaAliases = new ArrayList();ArrayList formulaTemplates = new ArrayList();ArrayList formulasLazy = new ArrayList();ArrayList types = new ArrayList();ArrayList names = new ArrayList();ArrayList classes = new ArrayList();ArrayList templates = new ArrayList();ArrayList propColumns = new ArrayList();ArrayList joinedFetchesList = new ArrayList();ArrayList cascades = new ArrayList();ArrayList definedBySubclass = new ArrayList();ArrayList propColumnNumbers = new ArrayList();ArrayList propFormulaNumbers = new ArrayList();ArrayList columnSelectables = new ArrayList();ArrayList propNullables = new ArrayList();iter = persistentClass.getSubclassPropertyClosureIterator();while ( iter.hasNext() ) {Property prop = ( Property ) iter.next();names.add( prop.getName() );classes.add( prop.getPersistentClass().getEntityName() );boolean isDefinedBySubclass = !thisClassProperties.contains( prop );definedBySubclass.add( Boolean.valueOf( isDefinedBySubclass ) );propNullables.add( Boolean.valueOf( prop.isOptional() || isDefinedBySubclass ) ); //TODO: is this completely correct?types.add( prop.getType() );Iterator colIter = prop.getColumnIterator();String[] cols = new String[prop.getColumnSpan()];String[] forms = new String[prop.getColumnSpan()];int[] colnos = new int[prop.getColumnSpan()];int[] formnos = new int[prop.getColumnSpan()];int l = 0;Boolean lazy = Boolean.valueOf( prop.isLazy() && lazyAvailable );while ( colIter.hasNext() ) {Selectable thing = ( Selectable ) colIter.next();if ( thing.isFormula() ) {String template = thing.getTemplate( factory.getDialect(), factory.getSqlFunctionRegistry() );formnos[l] = formulaTemplates.size();colnos[l] = -1;formulaTemplates.add( template );forms[l] = template;formulas.add( thing.getText( factory.getDialect() ) );formulaAliases.add( thing.getAlias( factory.getDialect() ) );formulasLazy.add( lazy );}else {String colName = thing.getTemplate( factory.getDialect(), factory.getSqlFunctionRegistry() );colnos[l] = columns.size(); //before add :-)formnos[l] = -1;columns.add( colName );cols[l] = colName;aliases.add( thing.getAlias( factory.getDialect(), prop.getValue().getTable() ) );columnsLazy.add( lazy );columnSelectables.add( Boolean.valueOf( prop.isSelectable() ) );}l++;}propColumns.add( cols );templates.add( forms );propColumnNumbers.add( colnos );propFormulaNumbers.add( formnos );joinedFetchesList.add( prop.getValue().getFetchMode() );cascades.add( prop.getCascadeStyle() );}subclassColumnClosure = ArrayHelper.toStringArray( columns );subclassColumnAliasClosure = ArrayHelper.toStringArray( aliases );subclassColumnLazyClosure = ArrayHelper.toBooleanArray( columnsLazy );subclassColumnSelectableClosure = ArrayHelper.toBooleanArray( columnSelectables );subclassFormulaClosure = ArrayHelper.toStringArray( formulas );subclassFormulaTemplateClosure = ArrayHelper.toStringArray( formulaTemplates );subclassFormulaAliasClosure = ArrayHelper.toStringArray( formulaAliases );subclassFormulaLazyClosure = ArrayHelper.toBooleanArray( formulasLazy );subclassPropertyNameClosure = ArrayHelper.toStringArray( names );subclassPropertySubclassNameClosure = ArrayHelper.toStringArray( classes );subclassPropertyTypeClosure = ArrayHelper.toTypeArray( types );subclassPropertyNullabilityClosure = ArrayHelper.toBooleanArray( propNullables );subclassPropertyFormulaTemplateClosure = ArrayHelper.to2DStringArray( templates );subclassPropertyColumnNameClosure = ArrayHelper.to2DStringArray( propColumns );subclassPropertyColumnNumberClosure = ArrayHelper.to2DIntArray( propColumnNumbers );subclassPropertyFormulaNumberClosure = ArrayHelper.to2DIntArray( propFormulaNumbers );subclassPropertyCascadeStyleClosure = new CascadeStyle[cascades.size()];iter = cascades.iterator();int j = 0;while ( iter.hasNext() ) {subclassPropertyCascadeStyleClosure[j++] = ( CascadeStyle ) iter.next();}subclassPropertyFetchModeClosure = new FetchMode[joinedFetchesList.size()];iter = joinedFetchesList.iterator();j = 0;while ( iter.hasNext() ) {subclassPropertyFetchModeClosure[j++] = ( FetchMode ) iter.next();}propertyDefinedOnSubclass = new boolean[definedBySubclass.size()];iter = definedBySubclass.iterator();j = 0;while ( iter.hasNext() ) {propertyDefinedOnSubclass[j++] = ( ( Boolean ) iter.next() ).booleanValue();}// Handle any filters applied to the class levelfilterHelper = new FilterHelper( persistentClass.getFilterMap(), factory.getDialect(), factory.getSqlFunctionRegistry() );temporaryIdTableName = persistentClass.getTemporaryIdTableName();temporaryIdTableDDL = persistentClass.getTemporaryIdTableDDL();}

我们看下语句：postConstruct(mapping);它的具体实现是这样：

protected void postConstruct(Mapping mapping) throws MappingException {initPropertyPaths(mapping);//insert/update/delete SQLfinal int joinSpan = getTableSpan();sqlDeleteStrings = new String[joinSpan];sqlInsertStrings = new String[joinSpan];sqlUpdateStrings = new String[joinSpan];sqlLazyUpdateStrings = new String[joinSpan];sqlUpdateByRowIdString = rowIdName == null ?null :generateUpdateString( getPropertyUpdateability(), 0, true );sqlLazyUpdateByRowIdString = rowIdName == null ?null :generateUpdateString( getNonLazyPropertyUpdateability(), 0, true );for ( int j = 0; j < joinSpan; j++ ) {sqlInsertStrings[j] = customSQLInsert[j] == null ?generateInsertString( getPropertyInsertability(), j ) :customSQLInsert[j];sqlUpdateStrings[j] = customSQLUpdate[j] == null ?generateUpdateString( getPropertyUpdateability(), j, false ) :customSQLUpdate[j];sqlLazyUpdateStrings[j] = customSQLUpdate[j] == null ?generateUpdateString( getNonLazyPropertyUpdateability(), j, false ) :customSQLUpdate[j];sqlDeleteStrings[j] = customSQLDelete[j] == null ?generateDeleteString( j ) :customSQLDelete[j];}tableHasColumns = new boolean[joinSpan];for ( int j = 0; j < joinSpan; j++ ) {tableHasColumns[j] = sqlUpdateStrings[j] != null;}//select SQLsqlSnapshotSelectString = generateSnapshotSelectString();sqlLazySelectString = generateLazySelectString();sqlVersionSelectString = generateSelectVersionString();if ( hasInsertGeneratedProperties() ) {sqlInsertGeneratedValuesSelectString = generateInsertGeneratedValuesSelectString();}if ( hasUpdateGeneratedProperties() ) {sqlUpdateGeneratedValuesSelectString = generateUpdateGeneratedValuesSelectString();}if ( isIdentifierAssignedByInsert() ) {identityDelegate = ( ( PostInsertIdentifierGenerator ) getIdentifierGenerator() ).getInsertGeneratedIdentifierDelegate( this, getFactory().getDialect(), useGetGeneratedKeys() );sqlIdentityInsertString = customSQLInsert[0] == null? generateIdentityInsertString( getPropertyInsertability() ): customSQLInsert[0];}else {sqlIdentityInsertString = null;}logStaticSQL();}

我为什么要看到这里呢，因为我不知道hibernate是怎么生成SQL语句的，而且我纠结这个花了我几天时间，所以宁可这里多贴一点源码，我们可以看到AbstractEntityPersister这个类中的几个给SQL赋值的变量在这里初始化了：

sqlDeleteStrings = new String[joinSpan];sqlInsertStrings = new String[joinSpan];sqlUpdateStrings = new String[joinSpan];sqlLazyUpdateStrings = new String[joinSpan];

接着依次执行下面方法：

generateInsertString( getPropertyInsertability(), j ) :customSQLInsert[j];

protected String generateInsertString(boolean[] includeProperty, int j) {return generateInsertString( false, includeProperty, j );}

/** * Generate the SQL that inserts a row */protected String generateInsertString(boolean identityInsert, boolean[] includeProperty, int j) {// todo : remove the identityInsert param and variations;//   identity-insert strings are now generated from generateIdentityInsertString()Insert insert = new Insert( getFactory().getDialect() ).setTableName( getTableName( j ) );// add normal propertiesfor ( int i = 0; i < entityMetamodel.getPropertySpan(); i++ ) {if ( includeProperty[i] && isPropertyOfTable( i, j ) ) {// this property belongs on the table and is to be insertedinsert.addColumns( getPropertyColumnNames(i), propertyColumnInsertable[i] );}}// add the discriminatorif ( j == 0 ) {addDiscriminatorToInsert( insert );}// add the primary keyif ( j == 0 && identityInsert ) {insert.addIdentityColumn( getKeyColumns( 0 )[0] );}else {insert.addColumns( getKeyColumns( j ) );}if ( getFactory().getSettings().isCommentsEnabled() ) {insert.setComment( "insert " + getEntityName() );}String result = insert.toStatementString();// append the SQL to return the generated identifierif ( j == 0 && identityInsert && useInsertSelectIdentity() ) { //TODO: suck into Insertresult = getFactory().getDialect().appendIdentitySelectToInsert( result );}return result;}

public String toStatementString() {StringBuffer buf = new StringBuffer( columns.size()*15 + tableName.length() + 10 );if ( comment != null ) {buf.append( "/* " ).append( comment ).append( " */ " );}buf.append("insert into ").append(tableName);if ( columns.size()==0 ) {buf.append(' ').append( dialect.getNoColumnsInsertString() );}else {buf.append(" (");Iterator iter = columns.keySet().iterator();while ( iter.hasNext() ) {buf.append( iter.next() );if ( iter.hasNext() ) {buf.append( ", " );}}buf.append(") values (");iter = columns.values().iterator();while ( iter.hasNext() ) {buf.append( iter.next() );if ( iter.hasNext() ) {buf.append( ", " );}}buf.append(')');}return buf.toString();}

执行完这里，SQL语句就算是拼接完成了