在tomcat中配置jndi resource资源

1. 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()%>