在tomcat中配置jndi resource资源

car.3205

• 创建JndiResourceFactory
  

　　实现javax.naming.spi.ObjectFactory接口，该工场的功能是创建resource object对象。

import java.util.Enumeration;
import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.Name;
import javax.naming.NamingException;
import javax.naming.RefAddr;
import javax.naming.Reference;
import javax.naming.spi.ObjectFactory;
public class MyBeanFactory implements ObjectFactory {
public Object getObjectInstance(Object obj, Name name, Context nameCtx,
Hashtable environment) throws NamingException {
// Acquire an instance of our specified bean class
MyBean bean = new MyBean();
// Customize the bean properties from our attributes
Reference ref = (Reference) obj;
Enumeration addrs = ref.getAll();
while (addrs.hasMoreElements()) {
RefAddr addr = (RefAddr) addrs.nextElement();
String value = (String) addr.getContent();
if (addr.getType().equals("foo")) {
bean.setFoo(value);
} else if (addr.getType().equals("bar")) {
try {
bean.setBar(Integer.parseInt(value));
} catch (NumberFormatException e) {
throw new NamingException("Invalid 'bar' value " + value);
}
}
}
// Return the customized instance
return (bean);
}
}
　　可以将jndi的资源配置到server.xml中的GlobalNamingResources 配置项中，例如：

<GlobalNamingResources>
<Resource name="bean/cmsFileObservable" auth="Container" type="java.util.Observable"
factory="com.koubei.cmsoptim.tomcat.extend.JspUpdateResourceFactory" />
</GlobalNamingResources>
　　http://tomcat.apache.org/tomcat-6.0-doc/config/globalresources.html
　　唯一的不方便的地方是在GlobalNamingResources中配置的resource资源在web应用的context中默认是不可见的，必须要使用

<Context>
<ResourceLink
name="bean/MyBeanFactory"
global="bean/MyBeanFactory"
type="com.mycompany.MyBean"
/>
</Context>

　　才能在web应用中引用到GlobalNamingResources定义的context对象，如果在每个web应用中都配置，那会比较麻烦，但是可以将ResourceLink 配置到%catalina.home%/conf/context.xml 这个配置文件中，这样所有web应用都能共享这个resource 对象了

<!-- The contents of this file will be loaded for each web application -->
<Context>
<ResourceLink    name="bean/cmsFileObservable"
global="bean/cmsFileObservable"
type="java.util.Observable"/>
<!-- Default set of monitored resources -->
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<!-- Uncomment this to disable session persistence across Tomcat restarts -->
<!--
<Manager pathname="" />
-->
<!-- Uncomment this to enable Comet connection tacking (provides events
on session expiration as well as webapp lifecycle) -->
<!--
<Valve className="org.apache.catalina.valves.CometConnectionManagerValve" />
-->
</Context>
　　使用jndi容器中的对象

<%@page import="com.koubei.resource.MyBean" %>
<%@page import="javax.naming.InitialContext" %>
<%@page import="javax.naming.Context" %>

<%
Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
MyBean bean = (MyBean) envCtx.lookup("bean/MyBeanFactory");
%>
<%="foo = " + bean.getFoo() + ", bar = " + bean.getBar()%>