reffruitfactory.java~13~

来自「JNDI课件」· JAVA~13~ 代码 · 共 56 行

package jndi;
/*工厂类，曾海2003-9-13

程序要求：１带一个无参构造　２　必须实现getObjectInstance
程序功能是：检查引用内容，如果引用是引用RefFruit的，
就取得地址，而后返回一个对象，对象工厂么！这个方法是由容器调用的,当你
ctx.lookup的时候，返回的只是一个引用，我们要把引用变化成对象，此时调用它.

LDAP service provider invoked DirectoryManager.getObjectInstance() and
supplied the method the data (a reference) that
the provider read from the directory for the entry "cn=favorite".

The reference identified FruitFactory as the object factory's class name.
FruitFactory.getObjectInstance() returned an instance of Fruit.

*/
import javax.naming.*;
import javax.naming.spi.ObjectFactory;
import java.util.Hashtable;


public class RefFruitFactory  implements ObjectFactory {

  public RefFruitFactory() {
  }

  public Object getObjectInstance(Object obj, Name name, Context ctx, Hashtable env) throws Exception {
        if (obj instanceof Reference) {//如果obj是引用

          Reference ref = (Reference)obj;
         Class c = RefFruit.class;
         if (ref.getClassName().equals(RefFruit.class.getName())) {

                RefAddr addr = ref.get("reffruit");//这句话是取这个引用的地址
                //在Reffruit类里有    new StringRefAddr("reffruit", fruit)
                //"reffruit"是地址类型，fruit是构造参数，本例中是new Reffruit("xxx")里的xxx
                //addr里存的就是一个字串地址，比如"green"
                //所以你得先定义Reffruit才行


                if (addr != null) {
                    return new RefFruit(  (String)addr.getContent()  );
                }
            }
        }
        return null;
    }



}