https://openjdk.java.net/ 
/*
 * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package javax.naming;

import java.util.Vector;
import java.util.Enumeration;


This class represents a reference to an object that is found outside of
the naming/directory system.


Reference provides a way of recording address information about
objects which themselves are not directly bound to the naming/directory system.


A Reference consists of an ordered list of addresses and class information
about the object being referenced.
Each address in the list identifies a communications endpoint
for the same conceptual object.  The "communications endpoint"
is information that indicates how to contact the object. It could
be, for example, a network address, a location in memory on the
local machine, another process on the same machine, etc.
The order of the addresses in the list may be of significance
to object factories that interpret the reference.


Multiple addresses may arise for
various reasons, such as replication or the object offering interfaces
over more than one communication mechanism.  The addresses are indexed
starting with zero.


A Reference also contains information to assist in creating an instance
of the object to which this Reference refers.  It contains the class name
of that object, and the class name and location of the factory to be used
to create the object.
The class factory location is a space-separated list of URLs representing
the class path used to load the factory.  When the factory class (or
any class or resource upon which it depends) needs to be loaded,
each URL is used (in order) to attempt to load the class.


A Reference instance is not synchronized against concurrent access by multiple
threads. Threads that need to access a single Reference concurrently should
synchronize amongst themselves and provide the necessary locking.

Author:Rosanna Lee, Scott Seligman
See Also:
Since:1.3
/**
  * This class represents a reference to an object that is found outside of
  * the naming/directory system.
  *<p>
  * Reference provides a way of recording address information about
  * objects which themselves are not directly bound to the naming/directory system.
  *<p>
  * A Reference consists of an ordered list of addresses and class information
  * about the object being referenced.
  * Each address in the list identifies a communications endpoint
  * for the same conceptual object.  The "communications endpoint"
  * is information that indicates how to contact the object. It could
  * be, for example, a network address, a location in memory on the
  * local machine, another process on the same machine, etc.
  * The order of the addresses in the list may be of significance
  * to object factories that interpret the reference.
  *<p>
  * Multiple addresses may arise for
  * various reasons, such as replication or the object offering interfaces
  * over more than one communication mechanism.  The addresses are indexed
  * starting with zero.
  *<p>
  * A Reference also contains information to assist in creating an instance
  * of the object to which this Reference refers.  It contains the class name
  * of that object, and the class name and location of the factory to be used
  * to create the object.
  * The class factory location is a space-separated list of URLs representing
  * the class path used to load the factory.  When the factory class (or
  * any class or resource upon which it depends) needs to be loaded,
  * each URL is used (in order) to attempt to load the class.
  *<p>
  * A Reference instance is not synchronized against concurrent access by multiple
  * threads. Threads that need to access a single Reference concurrently should
  * synchronize amongst themselves and provide the necessary locking.
  *
  * @author Rosanna Lee
  * @author Scott Seligman
  *
  * @see RefAddr
  * @see StringRefAddr
  * @see BinaryRefAddr
  * @since 1.3
  */

  /*<p>
  * The serialized form of a Reference object consists of the class
  * name of the object being referenced (a String), a Vector of the
  * addresses (each a RefAddr), the name of the class factory (a
  * String), and the location of the class factory (a String).
*/


public class Reference implements Cloneable, java.io.Serializable {
    
Contains the fully-qualified name of the class of the object to which
this Reference refers.

See Also:
@serial
/**
     * Contains the fully-qualified name of the class of the object to which
     * this Reference refers.
     * @serial
     * @see java.lang.Class#getName
     */
    protected String className;
    
Contains the addresses contained in this Reference.
Initialized by constructor.

@serial
/**
     * Contains the addresses contained in this Reference.
     * Initialized by constructor.
     * @serial
     */
    protected Vector<RefAddr> addrs = null;

    
Contains the name of the factory class for creating
an instance of the object to which this Reference refers.
Initialized to null.

@serial
/**
     * Contains the name of the factory class for creating
     * an instance of the object to which this Reference refers.
     * Initialized to null.
     * @serial
     */
    protected String classFactory = null;

    
Contains the location of the factory class.
Initialized to null.

@serial
/**
     * Contains the location of the factory class.
     * Initialized to null.
     * @serial
     */
    protected String classFactoryLocation = null;

    
Constructs a new reference for an object with class name 'className'.
Class factory and class factory location are set to null.
The newly created reference contains zero addresses.

Params:
  • className – The non-null class name of the object to which
this reference refers.
/**
      * Constructs a new reference for an object with class name 'className'.
      * Class factory and class factory location are set to null.
      * The newly created reference contains zero addresses.
      *
      * @param className The non-null class name of the object to which
      * this reference refers.
      */
    public Reference(String className) {
        this.className  = className;
        addrs = new Vector<>();
    }

    
Constructs a new reference for an object with class name 'className' and
an address.
Class factory and class factory location are set to null.

Params:
  • className – The non-null class name of the object to
which this reference refers.
  • addr – The non-null address of the object.
/**
      * Constructs a new reference for an object with class name 'className' and
      * an address.
      * Class factory and class factory location are set to null.
      *
      * @param className The non-null class name of the object to
      * which this reference refers.
      * @param addr The non-null address of the object.
      */
    public Reference(String className, RefAddr addr) {
        this.className = className;
        addrs = new Vector<>();
        addrs.addElement(addr);
    }

    
Constructs a new reference for an object with class name 'className',
and the class name and location of the object's factory.

Params:
  • className – The non-null class name of the object to which
                        this reference refers.
  • factory –  The possibly null class name of the object's factory.
  • factoryLocation – 
        The possibly null location from which to load
        the factory (e.g. URL)
See Also:
/**
      * Constructs a new reference for an object with class name 'className',
      * and the class name and location of the object's factory.
      *
      * @param className The non-null class name of the object to which
      *                         this reference refers.
      * @param factory  The possibly null class name of the object's factory.
      * @param factoryLocation
      *         The possibly null location from which to load
      *         the factory (e.g. URL)
      * @see javax.naming.spi.ObjectFactory
      * @see javax.naming.spi.NamingManager#getObjectInstance
      */
    public Reference(String className, String factory, String factoryLocation) {
        this(className);
        classFactory = factory;
        classFactoryLocation = factoryLocation;
    }

    
Constructs a new reference for an object with class name 'className',
the class name and location of the object's factory, and the address for
the object.

Params:
  • className – The non-null class name of the object to
        which this reference refers.
  • factory –  The possibly null class name of the object's factory.
  • factoryLocation –  The possibly null location from which
                        to load the factory (e.g. URL)
  • addr –     The non-null address of the object.
See Also:
/**
      * Constructs a new reference for an object with class name 'className',
      * the class name and location of the object's factory, and the address for
      * the object.
      *
      * @param className The non-null class name of the object to
      *         which this reference refers.
      * @param factory  The possibly null class name of the object's factory.
      * @param factoryLocation  The possibly null location from which
      *                         to load the factory (e.g. URL)
      * @param addr     The non-null address of the object.
      * @see javax.naming.spi.ObjectFactory
      * @see javax.naming.spi.NamingManager#getObjectInstance
      */
    public Reference(String className, RefAddr addr,
                     String factory, String factoryLocation) {
        this(className, addr);
        classFactory = factory;
        classFactoryLocation = factoryLocation;
    }

    
Retrieves the class name of the object to which this reference refers.

Returns:The non-null fully-qualified class name of the object.
        (e.g. "java.lang.String")
/**
      * Retrieves the class name of the object to which this reference refers.
      *
      * @return The non-null fully-qualified class name of the object.
      *         (e.g. "java.lang.String")
      */
    public String getClassName() {
        return className;
    }

    
Retrieves the class name of the factory of the object
to which this reference refers.

Returns:The possibly null fully-qualified class name of the factory.
        (e.g. "java.lang.String")
/**
      * Retrieves the class name of the factory of the object
      * to which this reference refers.
      *
      * @return The possibly null fully-qualified class name of the factory.
      *         (e.g. "java.lang.String")
      */
    public String getFactoryClassName() {
        return classFactory;
    }

    
Retrieves the location of the factory of the object
to which this reference refers.
If it is a codebase, then it is an ordered list of URLs,
separated by spaces, listing locations from where the factory
class definition should be loaded.

Returns:The possibly null string containing the
                location for loading in the factory's class.
/**
      * Retrieves the location of the factory of the object
      * to which this reference refers.
      * If it is a codebase, then it is an ordered list of URLs,
      * separated by spaces, listing locations from where the factory
      * class definition should be loaded.
      *
      * @return The possibly null string containing the
      *                 location for loading in the factory's class.
      */
    public String getFactoryClassLocation() {
        return classFactoryLocation;
    }

    
Retrieves the first address that has the address type 'addrType'.
String.compareTo() is used to test the equality of the address types.

Params:
  • addrType – The non-null address type for which to find the address.
Returns:The address in this reference with address type 'addrType';
        null if no such address exists.
/**
      * Retrieves the first address that has the address type 'addrType'.
      * String.compareTo() is used to test the equality of the address types.
      *
      * @param addrType The non-null address type for which to find the address.
      * @return The address in this reference with address type 'addrType';
      *         null if no such address exists.
      */
    public RefAddr get(String addrType) {
        int len = addrs.size();
        RefAddr addr;
        for (int i = 0; i < len; i++) {
            addr = addrs.elementAt(i);
            if (addr.getType().compareTo(addrType) == 0)
                return addr;
        }
        return null;
    }

    
Retrieves the address at index posn.

Params:
  • posn – The index of the address to retrieve.
Throws:
Returns:The address at the 0-based index posn. It must be in the
        range [0,getAddressCount()).
/**
      * Retrieves the address at index posn.
      * @param posn The index of the address to retrieve.
      * @return The address at the 0-based index posn. It must be in the
      *         range [0,getAddressCount()).
      * @exception ArrayIndexOutOfBoundsException If posn not in the specified
      *         range.
      */
    public RefAddr get(int posn) {
        return addrs.elementAt(posn);
    }

    
Retrieves an enumeration of the addresses in this reference.
When addresses are added, changed or removed from this reference,
its effects on this enumeration are undefined.

Returns:An non-null enumeration of the addresses (RefAddr) in this reference. If this reference has zero addresses, an enumeration with zero elements is returned.
/**
      * Retrieves an enumeration of the addresses in this reference.
      * When addresses are added, changed or removed from this reference,
      * its effects on this enumeration are undefined.
      *
      * @return An non-null enumeration of the addresses
      *         ({@code RefAddr}) in this reference.
      *         If this reference has zero addresses, an enumeration with
      *         zero elements is returned.
      */
    public Enumeration<RefAddr> getAll() {
        return addrs.elements();
    }

    
Retrieves the number of addresses in this reference.

Returns:The nonnegative number of addresses in this reference.
/**
      * Retrieves the number of addresses in this reference.
      *
      * @return The nonnegative number of addresses in this reference.
      */
    public int size() {
        return addrs.size();
    }

    
Adds an address to the end of the list of addresses.

Params:
  • addr – The non-null address to add.
/**
      * Adds an address to the end of the list of addresses.
      *
      * @param addr The non-null address to add.
      */
    public void add(RefAddr addr) {
        addrs.addElement(addr);
    }

    
Adds an address to the list of addresses at index posn.
All addresses at index posn or greater are shifted up
the list by one (away from index 0).

Params:
  • posn – The 0-based index of the list to insert addr.
  • addr – The non-null address to add.
Throws:
/**
      * Adds an address to the list of addresses at index posn.
      * All addresses at index posn or greater are shifted up
      * the list by one (away from index 0).
      *
      * @param posn The 0-based index of the list to insert addr.
      * @param addr The non-null address to add.
      * @exception ArrayIndexOutOfBoundsException If posn not in the specified
      *         range.
      */
    public void add(int posn, RefAddr addr) {
        addrs.insertElementAt(addr, posn);
    }

    
Deletes the address at index posn from the list of addresses.
All addresses at index greater than posn are shifted down
the list by one (towards index 0).

Params:
  • posn – The 0-based index of in address to delete.
Throws:
Returns:The address removed.
/**
      * Deletes the address at index posn from the list of addresses.
      * All addresses at index greater than posn are shifted down
      * the list by one (towards index 0).
      *
      * @param posn The 0-based index of in address to delete.
      * @return The address removed.
      * @exception ArrayIndexOutOfBoundsException If posn not in the specified
      *         range.
      */
    public Object remove(int posn) {
        Object r = addrs.elementAt(posn);
        addrs.removeElementAt(posn);
        return r;
    }

    
Deletes all addresses from this reference.

/**
      * Deletes all addresses from this reference.
      */
    public void clear() {
        addrs.setSize(0);
    }

    
Determines whether obj is a reference with the same addresses
(in same order) as this reference.
The addresses are checked using RefAddr.equals().
In addition to having the same addresses, the Reference also needs to
have the same class name as this reference.
The class factory and class factory location are not checked.
If obj is null or not an instance of Reference, null is returned.

Params:
  • obj – The possibly null object to check.
Returns:true if obj is equal to this reference; false otherwise.
/**
      * Determines whether obj is a reference with the same addresses
      * (in same order) as this reference.
      * The addresses are checked using RefAddr.equals().
      * In addition to having the same addresses, the Reference also needs to
      * have the same class name as this reference.
      * The class factory and class factory location are not checked.
      * If obj is null or not an instance of Reference, null is returned.
      *
      * @param obj The possibly null object to check.
      * @return true if obj is equal to this reference; false otherwise.
      */
    public boolean equals(Object obj) {
        if ((obj != null) && (obj instanceof Reference)) {
            Reference target = (Reference)obj;
            // ignore factory information
            if (target.className.equals(this.className) &&
                target.size() ==  this.size()) {
                Enumeration<RefAddr> mycomps = getAll();
                Enumeration<RefAddr> comps = target.getAll();
                while (mycomps.hasMoreElements())
                    if (!(mycomps.nextElement().equals(comps.nextElement())))
                        return false;
                return true;
            }
        }
        return false;
    }

    
Computes the hash code of this reference.
The hash code is the sum of the hash code of its addresses.

Returns:A hash code of this reference as an int.
/**
      * Computes the hash code of this reference.
      * The hash code is the sum of the hash code of its addresses.
      *
      * @return A hash code of this reference as an int.
      */
    public int hashCode() {
        int hash = className.hashCode();
        for (Enumeration<RefAddr> e = getAll(); e.hasMoreElements();)
            hash += e.nextElement().hashCode();
        return hash;
    }

    
Generates the string representation of this reference.
The string consists of the class name to which this reference refers,
and the string representation of each of its addresses.
This representation is intended for display only and not to be parsed.

Returns:The non-null string representation of this reference.
/**
      * Generates the string representation of this reference.
      * The string consists of the class name to which this reference refers,
      * and the string representation of each of its addresses.
      * This representation is intended for display only and not to be parsed.
      *
      * @return The non-null string representation of this reference.
      */
    public String toString() {
        StringBuilder sb = new StringBuilder("Reference Class Name: " +
                                             className + "\n");
        int len = addrs.size();
        for (int i = 0; i < len; i++)
            sb.append(get(i).toString());

        return sb.toString();
    }

    
Makes a copy of this reference using its class name
list of addresses, class factory name and class factory location.
Changes to the newly created copy does not affect this Reference
and vice versa.

/**
     * Makes a copy of this reference using its class name
     * list of addresses, class factory name and class factory location.
     * Changes to the newly created copy does not affect this Reference
     * and vice versa.
     */
    public Object clone() {
        Reference r = new Reference(className, classFactory, classFactoryLocation);
        Enumeration<RefAddr> a = getAll();
        r.addrs = new Vector<>();

        while (a.hasMoreElements())
            r.addrs.addElement(a.nextElement());
        return r;
    }
    
Use serialVersionUID from JNDI 1.1.1 for interoperability

/**
     * Use serialVersionUID from JNDI 1.1.1 for interoperability
     */
    private static final long serialVersionUID = -1673475790065791735L;
};