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>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>??

<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. ?

?*/??

/*** 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; ??

/** ?

?*?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(); ??

????} ??

}??

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();}}

現在揭曉謎底：很簡單，對于JndiObjectFactoryBean對象，spring IOC容器啟動時確實造了它的對象，只不過這時是工廠本身，spring會自動調用工廠里的afterPropertiesSet()方法去造真正需要的bean，然后調用getObject()和getObjectType()方法返回已造好的對象和類型，再將其準確的注入依賴它的其他bean里面，所以并沒有違背java的精神！

有興趣也可以看看org.springframework.orm.hibernate3.LocalSessionFactoryBean，它也實現了FactoryBean接口，內部實現如出一轍，只不過它擔負的重任不是造JNDI object，而是要造SessionFactory對象

?

?

?

?

?

?

?

=========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：

代碼類結構：



我們從上而下進行分析;
首先是：

JndiTemplate:

jndiTemplate提供了對JNDI服務器的vjndi對象的綁定，查詢，撤銷綁定和重新綁定，從一定意義上來說他跟JdbcTemplate等是同意概念的類，直接與資源管理器進行交互，并且同樣的是采用的回調機制，我們可以看見其依賴了JndiCallbake接口：

其對綁定，差性能，撤銷，重新綁定的實現的源代碼如下：

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());

????}

這段代碼生成了上下文，進而把上下文傳遞給了JndiCallBack,在這個接口的回調方法，我們直接使用context對資源管理器進行curd交互；

綁定對象：

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;

????????????}

????????});

????}

撤銷綁定：

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；

JndiAccessor:只是單純的對JndiTemplate進行了包裝，隔離了底層的實現細節；

JndiLocatorSupport的主要擴展的功能是，如果我們在配置JndiObjectFactoryBean的時候，配置了參數：resourceRef為true的話，那么就會如果我們查找的資源中間不包含:或者java:等前綴，我們會自動的會該路徑加上java:comp/env,主要是匹配在j2ee容器里面的jndi資源的查找；

????protected?String?convertJndiName(String?jndiName)?{

????????//?Prepend?container?prefix?if?not?already?specified?and?no?other?scheme?given.

????????if?(isResourceRef()?&&?!jndiName.startsWith(CONTAINER_PREFIX)?&&?jndiName.indexOf(':')?==?-1)?{

????????????jndiName?=?CONTAINER_PREFIX?+?jndiName;

????????}

????????return?jndiName;

????}

最后，我們再來看一下：

在JndiObjectFactoryBean我們實際上得到的是：

?? jndiObject :
初始化生成如下：

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'");

????????????}

????????????//?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();

????????}

????}

當proxyTnterface不為空的時候
this.jndiObject?=?JndiObjectProxyFactory.createJndiObjectProxy(this);
生成了一個從Jndi目錄中取得了的對象的代理類：

private?static?class?JndiObjectProxyFactory?{

????????private?static?Object?createJndiObjectProxy(JndiObjectFactoryBean?jof)?throws?NamingException?{

????????????//?Create?a?JndiObjectTargetSource?that?mirrors?the?JndiObjectFactoryBean's?configuration.

????????????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();

????????????//?Create?a?proxy?with?JndiObjectFactoryBean's?proxy?interface?and?the?JndiObjectTargetSource.

????????????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

以上是生活随笔為你收集整理的从源代码解读spring之DataSource实现和FactoryBean模式(JndiObjectFactoryBean)的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。