请各位帮忙看一下这个问题:
在jndi访问File System Service Provider(FSSP)时,先是bind一个reference,然后用lookup取出后,转型时报出异常:
java.lang.ClassCastException: javax.naming.Reference
怎么解决这个问题啊?
Code:
public static void main(String[] args){
try{
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.fscontext.RefFSContextFactory ");
env.put(Context.PROVIDER_URL, "file:///D:/workspace/SampleApp ");
Context ctx = new InitialContext(env);
ctx.rebind( "tmp/myBoundObject ",new MyObject());
Object obj =ctx.lookup( "tmp/myBoundObject ");
System.out.println( "Object is : " + obj.toString());
System.out.println( "Class Name is : " + obj.getClass().getName());
// Exception from below code
MyObject myobj = (MyObject)obj;
}catch(NamingException ne){
ne.printStackTrace();
System.out.println( "Problem is : " + ne);
}
}
如下是MyObject Class
public class MyObject implements Referenceable{
String myobj = "MyObject to String ";
public Reference getReference(){
return new Reference(MyObject.class.getName());
}
public void printMessage(){
System.out.println( "This is instance of MyObject ");
}
public String toString(){
return myobj;
}
}
------解决方法--------------------------------------------------------
javax.naming.Reference
着不到这个类,你的包是否引用够了?
------解决方法--------------------------------------------------------
这个jndi server是专门为文件系统服务的,随便绑一个对象不太好吧。
有空反编译下com.sun.jndi.fscontext.FSContextFactory,看看它的getObjectInstance()方法。
如果我没猜错,所有的可解析reference对象(指类型都是com.sun.jndi.fscontext.FSContext$FSFile)都将被正确地返回确切信息,否则直接返回reference,直接转就出错了
这属于JNDI SPI的问题