Hibernate3 : org.hibernate.cfg.Configuration解析

R.Zeus — Mon, 21 Aug 2006 13:12:00 GMT

Hibernate3 : org.hibernate.cfg.Configuration 解析

�W�一�ơ写文章�Q�不好的地方�Q�请口下留情哈�?/span>

org.hibernate.cfg.Configurations �Ҏ�� xml 文�g配置整个工作�q�程中所需要的参数。一�?/span>

我们会用 Configuration cfg = new Configuration().configure(); 创徏一个配�|�类。那么，�q�句话到底做了什么呢�Q?/span>

首先�Q?/span> new Configuration() 会做些什么呢�Q�我们来看他的源码：

protected Configuration(SettingsFactory settingsFactory) {

System.out.println("Configuration(SettingsFactory settingsFactory)");

this.settingsFactory = settingsFactory;

reset();

}

// 默认构造函敎ͼ��?/span> new SettingsFactory() �Q?/span> 然后调用

//protected Configuration(SettingsFactory settingsFactory)

public Configuration() {

this(new SettingsFactory());

}

reset() 初始化了很多变量�Q�感兴趣的可以去看源代码�Q�没有什么特别的地方�?/span>

接着�Q�调�?/span> configure() �Ҏ��Q?/span>

public Configuration configure() throws HibernateException {

configure("/hibernate.cfg.xml");

return this;

}

可以看出�Q�默认��?/span> hibernate.cfg.xml 文�g�Q�如果想用自定义的文�Ӟ��可以调用

configure(“�?xml�? �Ҏ��?/span>

public Configuration configure(String resource) throws HibernateException {

log.debug("configuring from resource: " + resource);

InputStream stream = getConfigurationInputStream(resource);

return doConfigure(stream, resource);

}

�Ҏ�� getConfigurationInputStream(resource) 得到文�g��， getConfigurationInputStream(resource) 调用 ConfigHelper.getResourceAsStream(resource) �?/span>

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 );

}

// �q�里的代码可能应该是 stream = Environment.class.getResourceAsStream( resource );

if ( stream == null ) {

Environment.class.getResourceAsStream( resource );

}

if ( stream == null ) {

stream = Environment.class.getClassLoader().getResourceAsStream( stripped );

}

if ( stream == null ) {

throw new HibernateException( resource + " not found" );

}

return stream;

}

然后 doConfigure(stream, resource) �?/span>

protected Configuration doConfigure(InputStream stream, String resourceName) throws HibernateException {

org.dom4j.Document doc;

try {

List errors = new ArrayList();

SAXReader saxReader = xmlHelper.createSAXReader(resourceName, errors, entityResolver);

doc = saxReader.read(new InputSource(stream));

if (errors.size() != 0) {

throw new MappingException(

"invalid configuration",

(Throwable) errors.get(0)

);

}

entityResolver 在初始��gؓ entityResolver = XMLHelper.DEFAULT_DTD_RESOLVER ; �?/span> reset() 的时候设�|�的�?/span> XMLHelper.DEFAULT_DTD_RESOLVE �?/span> XMLHelper 默认�?/span> XMLHelper.DEFAULT_DTD_RESOLVER= new DTDEntityResolver() �Q?/span> DTDEntityResolver 是用来加�?/span> dtd 文�g的。别跟我说你不知�?/span> dtd 是什么东西？它有 3 �U�加载方式：

1�Q?span style="FONT: 7pt 'Times New Roman'"> 文�g路径�?/span> http://hibernate.sourceforge.net/ 开头的文�g�Q�如

http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd �Q?/span>

它会�?/span> http://hibernate.sourceforge.net ��L��Q�加�?/span> org/hibernate/ �Q�文件�\径�ؓ

org/hibernate/hibernate-configuration-3.0.dtd �Q�然后加载这个文件�?/span>

2. 文�g路径�?/span> file:// 开头的文�g�Q�如

file://hibernate-configuration-3.0.dtd �Q?/span>

它会�?/span> file:// ��L��Q��\径�ؓ hibernate-configuration-3.0.dtd �Q�然后加载这个文件�?/span>

3. 如果没有以上 2 �U�情况，则直接加载。就是�\径名没有修改�q��?/span>

整个�q�程�?/span> public InputSource resolveEntity(String publicId, String systemId) 中实现�?/span>

systemId ��是 dtd 的�\径。大家可以去看看 SAXReader �c�自带的

protected static class SAXEntityResolver �Q�比较比较�?/span>

在得�?/span> doc 的�?/span>

doc = saxReader.read(new InputSource(stream));

后，调用 protected Configuration doConfigure(org.dom4j.Document doc) �Q�这个函��C��要是�Ҏ�� doc 的到配置参数�Q�然后存�?/span> properties 中�?/span>

先是讄�� session-factory 的名字：

Element sfNode = doc.getRootElement().element("session-factory");

String name = sfNode.attributeValue("name");

if (name != null) {

// 保存�?/span> properties 中！

properties.setProperty(Environment.SESSION_FACTORY_NAME, name);

}

然后�?/span> addProperties(sfNode) �Q�把保存�?/span> properties 中�?/span>

// �q�句话估计又是多余的

properties.setProperty(name, value);

if (!name.startsWith("hibernate")) {

properties.setProperty("hibernate." + name, value);

}

接着调用�?/span> parseSessionFactory(sfNode, name) �Q�把 mapping �Q?/span> class-cache �Q?/span> collection-cache �Q?/span> listener �Q?/span> event �{�配�|�保存。到底它保存到哪�Q�我也不全知道，只看�?/span>

protected void parseMappingElement(Element subelement, String name), �Ҏ��配置加蝲�?/span> mapping 的文�Ӟ��最后��?/span> HbmBinder : public static void bindRoot(Document doc, Mappings mappings, java.util.Map inheritedMetas) 保存�?/span> bindRoot 是对 mapping 中的 xml 文�g�q�行解析�?/span>

HbmBinder �?/span> Configuration 都有 2000 行以上的代码�Q�在 Hibernate 中有很重要的��C��?/span> Configuration 使用 .cfg.xml �Q��?/span> HbmBinder 则��用了 .hbm.xml �?/span>

extractRootAttributes( hmNode, mappings ) �Ҏ�� 的配�|�，把分析的�l�果存入 mapping �?/span>

R.Zeus 2006-08-21 21:12 发表评论

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Hibernate3 : org.hibernate.cfg.Configuration解析