从这篇文章中：http : //codelevain.wordpress.com/2010/12/18/url-as-jndi-
resource/

像这样在您的context.xml中定义您的FTP URL：

 <Resource name="url/SomeService" auth="Container"
 type="java.net.URL"
 factory="com.mycompany.common.URLFactory"
 url="ftp://ftpserver/folder" />

提供com.mycompany.common.URLFactory实现，并确保结果类可用于Tomcat：

import java.net.URL;
import java.util.Hashtable;
import javax.naming.*;
import javax.naming.spi.ObjectFactory;

public class URLFactory implements ObjectFactory {
 public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable environment) throws Exception {
 Reference ref = (Reference) obj;
 String urlString =  (String) ref.get("url").getContent();
 return new URL(urlString);
 }
}

在web.xml中创建参考

<resource-ref>
 <res-ref-name>
   url/SomeService
 </res-ref-name>
 <res-type>
   java.net.URL
 </res-type>
 <res-auth>
   Container
 </res-auth>
</resource-ref>

然后在您的代码中通过执行JNDI查找来获取FTP URL：

InitialContext context = new InitialContext();
URL url = (URL) context.lookup("java:comp/env/url/SomeService");