http://cuishen.iteye.com/blog/430735
大家平日使用spring + hibernate做項目的時候大概都接觸過下面的spring配置代碼：
下面是使用普通的jdbc驅動獲得DataSource的配置
Xml代碼 ?
< bean id "dataSource" class "org.springframework.jdbc.datasource.DriverManagerDataSource" > ????< property name "driverClassName" > < value > </ value > </ property > ????< property name "url" > < value > </ value > </ property > ????< property name "username" > < value > </ value > </ property > ????< property name "password" > < value > </ value > </ property > </ bean > < bean id "sessionFactory" class "org.springframework.orm.hibernate3.LocalSessionFactoryBean" > ????< property name "mappingResources" > < list > ?????????< value > </ value > ????</ list > </ property > ????< property name "hibernateProperties" > < props > ????????< prop key "dialect" > </ prop > ????????< prop key "connection.autocommit" > </ prop > ????</ props > </ property > ????< property name "dataSource" > < ref local "dataSource" /> </ property > </ bean > < bean id "txManager" class "org.springframework.orm.hibernate3.HibernateTransactionManager" > ????< property name "sessionFactory" > < ref local "sessionFactory" /> </ property > </ bean > < bean id "dao" class "com.conserv.dao.impl.HibernateDaoImpl" init-method "init" destroy-method "destroy" > ????< property name "transactionManager" > < ref local "txManager" /> </ property > ????< property name "dialect" > < value > </ value > </ property > </ bean >
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"><property name="driverClassName"><value>oracle.jdbc.OracleDriver</value></property><property name="url"><value>jdbc:oracle:thin:@caij-b815c8aab6:1521:cui</value></property><property name="username"><value>cuishen</value></property><property name="password"><value>cuishen</value></property></bean><bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"><property name="mappingResources"><list><value>com/cuishen/testDao/pojo/Test.hbm.xml</value></list></property><property name="hibernateProperties"><props><prop key="dialect">org.hibernate.dialect.Oracle9Dialect</prop><prop key="connection.autocommit">true</prop></props></property><property name="dataSource"><ref local="dataSource"/></property></bean><bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"><property name="sessionFactory"><ref local="sessionFactory"/></property></bean><bean id="dao" class="com.conserv.dao.impl.HibernateDaoImpl" init-method="init" destroy-method="destroy"><property name="transactionManager"><ref local="txManager"/></property><property name="dialect"><value>Oracle9</value></property></bean>
下面是通過JNDI獲得的DataSource的配置，只要將上面的id為"dataSource"的bean換成下面的配置就行了
Xml代碼 ?
< bean id "dataSource" class "org.springframework.jndi.JndiObjectFactoryBean" > ;property?name "jndiName" value "cs" /> </ bean >
<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean"> <property name="jndiName" value="cs" /> </bean>
配置很簡單，使用也非常方便，spring毫不挑食，不管是jdbc版的DataSource也好，是JNDI版的也好，它都能接受，那這個兼容性是怎么做到的呢？？現在從源代碼入手來一探究竟：
1. 先看看jdbc版的DataSource - org.springframework.jdbc.datasource.DriverManagerDataSource
Java代碼 ?
public ?class ?DriverManagerDataSource?extends ?AbstractDataSource??
public class DriverManagerDataSource extends AbstractDataSource
再看看這個AbstractDataSource：
Java代碼 ?
public ?abstract ?class ?AbstractDataSource?implements ?javax.sql.DataSource??
public abstract class AbstractDataSource implements javax.sql.DataSource
哈哈，原來DriverManagerDataSource是javax.sql.DataSource的實現類，那做為bean注入給sessionFactory真是無可厚非
我們再看看它內部的實現細節
Java代碼 ?
return ?DriverManager.getConnection(url,?props);??
return DriverManager.getConnection(url, props);
哈哈，這代碼是不是再熟悉也不過啦？原來DriverManagerDataSource實現了javax.sql.DataSource接口，本質是對jdbc連接數據庫的簡單封裝
2. 接下來看看JNDI版的DataSource - org.springframework.jndi.JndiObjectFactoryBean
Java代碼 ?
public ?class ?JndiObjectFactoryBean?extends ?JndiObjectLocator?implements ?FactoryBean??
public class JndiObjectFactoryBean extends JndiObjectLocator implements FactoryBean
追溯JndiObjectFactoryBean的父類和實現的接口以及父類的父類，都和javax.sql.DataSource接口八竿子打不著，沒有一點點淵源，oh，my God! 這怎么可能!?完全不相干的對象怎么能夠被注入？這完全有悖java的精神！但事實擺在眼前，測試是完全通過的！靜下心來，我注意到了JndiObjectFactoryBean實現了FactoryBean接口，一直以來腦子里對FactoryBean模式感到有點模糊，不能完全領會其本質，難道真的是這里面有文章？？好，借此機會，好好研究下FactoryBean接口，下面是org.springframework.beans.factory.FactoryBean源代碼里一段注釋：
Java代碼 ?
? ? ? ? ? ? ? ? ? ??
/*** Interface to be implemented by objects used within a BeanFactory* that are themselves factories. If a bean implements this interface,* it is used as a factory, not directly as a bean.** <p><b>NB: A bean that implements this interface cannot be used* as a normal bean.</b> A FactoryBean is defined in a bean style,* but the object exposed for bean references is always the object* that it creates.*/
翻譯過來是說：所有實現FactoryBean接口的類都被當作工廠來使用，而不是簡單的直接當作bean來使用，FactoryBean實現類里定義了要生產的對象，并且由FactoryBean實現類來造該對象的實例，看到這里聰明的你大概已經能猜出個八九不離十了吧
我們回過頭來看看JndiObjectFactoryBean的實現細節
Java代碼 ?
private ?Object?jndiObject; ??? ? ? ?? public ?void ?afterPropertiesSet()?throws ?IllegalArgumentException,?NamingException?{ ??????super .afterPropertiesSet(); ?? ?? ????if ?(this .proxyInterface?!=?null )?{ ?? ????????if ?(this .defaultObject?!=?null )?{ ?? ????????????throw ?new ?IllegalArgumentException( ?? ????????????????????"'defaultObject'?is?not?supported?in?combination?with?'proxyInterface'" ); ?? ????????} ?? ?????????? ????????this .jndiObject?=?JndiObjectProxyFactory.createJndiObjectProxy(this ); ?? ????} ?? ?? ????else ?{ ?? ????????if ?(!this .lookupOnStartup?||?!this .cache)?{ ?? ????????????throw ?new ?IllegalArgumentException( ?? ????????????????"Cannot?deactivate?'lookupOnStartup'?or?'cache'?without?specifying?a?'proxyInterface'" ); ?? ????????} ?? ????????if ?(this .defaultObject?!=?null ?&&?getExpectedType()?!=?null ?&& ?? ????????????????!getExpectedType().isInstance(this .defaultObject))?{ ?? ????????????throw ?new ?IllegalArgumentException("Default?object?[" ?+?this .defaultObject?+ ?? ????????????????????"]?of?type?[" ?+?this .defaultObject.getClass().getName()?+ ?? ????????????????????"]?is?not?of?expected?type?[" ?+?getExpectedType().getName()?+?"]" ); ?? ????????} ?? ???????? ?? ????????this .jndiObject?=?lookupWithFallback(); ?? ????} ?? } ?? ? ? ? ?? public ?Object?getObject()?{ ??????return ?this .jndiObject; ?? } ?? ?? public ?Class?getObjectType()?{ ??????if ?(this .proxyInterface?!=?null )?{ ?? ????????return ?this .proxyInterface; ?? ????} ?? ????else ?if ?(this .jndiObject?!=?null )?{ ?? ????????return ?this .jndiObject.getClass(); ?? ????} ?? ????else ?{ ?? ????????return ?getExpectedType(); ?? ????} ?? }??
private Object jndiObject;/*** Look up the JNDI object and store it.* 廣義上說是造對象的過程，就本例而言，是通過JNDI獲得DataSource對象*/public void afterPropertiesSet() throws IllegalArgumentException, NamingException {super.afterPropertiesSet();if (this.proxyInterface != null) {if (this.defaultObject != null) {throw new IllegalArgumentException("'defaultObject' is not supported in combination with 'proxyInterface'");}// We need a proxy and a JndiObjectTargetSource.this.jndiObject = JndiObjectProxyFactory.createJndiObjectProxy(this);}else {if (!this.lookupOnStartup || !this.cache) {throw new IllegalArgumentException("Cannot deactivate 'lookupOnStartup' or 'cache' without specifying a 'proxyInterface'");}if (this.defaultObject != null && getExpectedType() != null &&!getExpectedType().isInstance(this.defaultObject)) {throw new IllegalArgumentException("Default object [" + this.defaultObject +"] of type [" + this.defaultObject.getClass().getName() +"] is not of expected type [" + getExpectedType().getName() + "]");}// Locate specified JNDI object.this.jndiObject = lookupWithFallback();}}/*** Return the singleton JNDI object.* 返回JNDI對象（DataSource對象）*/public Object getObject() {return this.jndiObject;}public Class getObjectType() {if (this.proxyInterface != null) {return this.proxyInterface;}else if (this.jndiObject != null) {return this.jndiObject.getClass();}else {return getExpectedType();}}
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=========http://blog.csdn.net/turkeyzhou/article/details/3139258
在此之前，我已經接觸到了DataSource和JTA事務了，我們都應用到了JNDI技術；在Spring中提供了JNDI技術的整合支持，JNDI如何使用，我就不累贅了，具體我們來看一下整合的源代碼：
public ?Object?execute(JndiCallback?contextCallback)?throws?NamingException?{????????Context?ctx?=?createInitialContext(); ????????try ?{ ????????????return ?contextCallback.doInContext(ctx); ????????} ????????finally ?{ ????????????try ?{ ????????????????ctx.close(); ????????????} ????????????catch ?(NamingException?ex)?{ ????????????????logger.debug("Could?not?close?JNDI?InitialContext" ,?ex); ????????????} ????????} ????}
????protected ?Context?createInitialContext()?throws?NamingException?{ ????????return ?new ?InitialContext(getEnvironment()); ????}
public ?Object?lookup(final?String?name)?throws?NamingException?{????????if ?(logger.isDebugEnabled())?{ ????????????logger.debug("Looking?up?JNDI?object?with?name?[" ?+?name?+?"]" ); ????????} ????????return ?execute(new ?JndiCallback()?{ ????????????public ?Object?doInContext(Context?ctx)?throws?NamingException?{ ????????????????Object?located?=?ctx.lookup(name); ????????????????if ?(located?==?null )?{ ????????????????????throw ?new ?NameNotFoundException( ????????????????????????????"JNDI?object?with?[" ?+?name?+?"]?not?found:?JNDI?implementation? returned?null "); ????????????????} ????????????????return ?located; ????????????} ????????}); ????}
????public ?void ?bind(final?String?name,?final?Object?object )?throws?NamingException?{ ????????if ?(logger.isDebugEnabled())?{ ????????????logger.debug("Binding?JNDI?object?with?name?[" ?+?name?+?"]" ); ????????} ????????execute(new ?JndiCallback()?{ ????????????public ?Object?doInContext(Context?ctx)?throws?NamingException?{ ????????????????ctx.bind(name,?object ); ????????????????return ?null ; ????????????} ????????}); ????}
重新綁定：
public ?void ?rebind(final?String?name,?final?Object?object )?throws?NamingException?{????????if ?(logger.isDebugEnabled())?{ ????????????logger.debug("Rebinding?JNDI?object?with?name?[" ?+?name?+?"]" ); ????????} ????????execute(new ?JndiCallback()?{ ????????????public ?Object?doInContext(Context?ctx)?throws?NamingException?{ ????????????????ctx.rebind(name,?object ); ????????????????return ?null ; ????????????} ????????}); ????}
public ?void ?unbind(final?String?name)?throws?NamingException?{????????if ?(logger.isDebugEnabled())?{ ????????????logger.debug("Unbinding?JNDI?object?with?name?[" ?+?name?+?"]" ); ????????} ????????execute(new ?JndiCallback()?{ ????????????public ?Object?doInContext(Context?ctx)?throws?NamingException?{ ????????????????ctx.unbind(name); ????????????????return ?null ; ????????????} ????????}); ????} ???? }
通過JndiTemplate,我們實現了底層訪問代碼;形成了具體實現層；與上層開來；
????protected ?String?convertJndiName(String?jndiName)?{ ???????? ????????if ?(isResourceRef()?&&?!jndiName.startsWith(CONTAINER_PREFIX)?&&?jndiName.indexOf(':' )?==?-1)?{ ????????????jndiName?=?CONTAINER_PREFIX?+?jndiName; ????????} ????????return ?jndiName; ????} 最后，我們再來看一下：
public ?void ?afterPropertiesSet()?throws?IllegalArgumentException,?NamingException?{????????super.afterPropertiesSet(); ????????if ?(this .proxyInterface?!=?null )?{ ????????????if ?(this .defaultObject?!=?null )?{ ????????????????throw ?new ?IllegalArgumentException( ????????????????????????"'defaultObject'?is?not?supported?in?combination?with?'proxyInterface'" ); ????????????} ???????????? ????????????this .jndiObject?=?JndiObjectProxyFactory.createJndiObjectProxy(this ); ????????} ????????else ?{ ????????????if ?(!this .lookupOnStartup?||?!this .cache)?{ ????????????????throw ?new ?IllegalArgumentException( ????????????????????"Cannot?deactivate?'lookupOnStartup'?or?'cache'?without?specifying?a?'proxyInterface'" ); ????????????} ????????????if ?(this .defaultObject?!=?null ?&&?getExpectedType()?!=?null ?&& ????????????????????!getExpectedType().isInstance(this .defaultObject))?{ ????????????????throw ?new ?IllegalArgumentException("Default?object?[" ?+?this .defaultObject?+ ????????????????????????"]?of?type?[" ?+?this .defaultObject.getClass().getName()?+ ????????????????????????"]?is?not?of?expected?type?[" ?+?getExpectedType().getName()?+?"]" ); ????????????} ???????????? ????????????this .jndiObject?=?lookupWithFallback(); ????????} ????}
this );
private ?static ?class ?JndiObjectProxyFactory?{????????private ?static ?Object?createJndiObjectProxy(JndiObjectFactoryBean?jof)?throws?NamingException?{ ???????????? ????????????JndiObjectTargetSource?targetSource?=?new ?JndiObjectTargetSource(); ????????????targetSource.setJndiTemplate(jof.getJndiTemplate()); ????????????targetSource.setJndiName(jof.getJndiName()); ????????????targetSource.setExpectedType(jof.getExpectedType()); ????????????targetSource.setResourceRef(jof.isResourceRef()); ????????????targetSource.setLookupOnStartup(jof.lookupOnStartup); ????????????targetSource.setCache(jof.cache); ????????????targetSource.afterPropertiesSet(); ???????????? ????????????ProxyFactory?proxyFactory?=?new ?ProxyFactory(); ????????????proxyFactory.addInterface(jof.proxyInterface); ????????????proxyFactory.setTargetSource(targetSource); ????????????return ?proxyFactory.getProxy(); ????????} ????}
否則直接將從目錄服務器中得到的對象暴露出來；如果查找出現異常，將會把DefaultObject暴露出來；
總結
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