enumvariant.java

java 与COM组件的连接桥

/*
 * Copyright (c) 1999-2004 Sourceforge JACOB Project.
 * All rights reserved. Originator: Dan Adler (http://danadler.com).
 * Get more information about JACOB at http://sourceforge.net/projects/jacob-project
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package com.jacob.com;

/**
 * An implementation of IEnumVariant based on code submitted by Thomas Hallgren
 * (mailto:[e-mail])
 */
public class EnumVariant extends JacobObject implements java.util.Enumeration {
    private int m_pIEnumVARIANT;

    private final Variant[] m_recBuf = new Variant[1];

    // this only gets called from JNI
    //
    protected EnumVariant(int pIEnumVARIANT) {
        m_pIEnumVARIANT = pIEnumVARIANT;
    }

    /**
     * @param disp
     */
    public EnumVariant(Dispatch disp) {
        int[] hres = new int[1];
        Variant evv = Dispatch.invokev(disp, 
                Dispatch.DISPID_NEWENUM,
                Dispatch.Get, 
                new Variant[0], hres);
        if (evv.getvt() != Variant.VariantObject)
            //
            // The DISPID_NEWENUM did not result in a valid object
            //
            throw new ComFailException("Can't obtain EnumVARIANT");

        EnumVariant tmp = evv.toEnumVariant();
        m_pIEnumVARIANT = tmp.m_pIEnumVARIANT;
        tmp.m_pIEnumVARIANT = 0;
    }

    /**
     * Implements java.util.Enumeration
     * @return boolean true if there are more elements in ths enumeration
     */
    public boolean hasMoreElements() {
        {
            if (m_recBuf[0] == null) {
                if (this.Next(m_recBuf) <= 0)
                    return false;
            }
            return true;
        }
    }

    /**
     * Implements java.util.Enumeration
     * @return next element in the enumeration
     */
    public Object nextElement() {
        Object last = m_recBuf[0];
        if (last == null) {
            if (this.Next(m_recBuf) <= 0)
                throw new java.util.NoSuchElementException();
            last = m_recBuf[0];
        }
        m_recBuf[0] = null;
        return last;
    }

    /**
     * Get next element in collection or null if at end
     * @return Variant that is next in the collection
     */
    public Variant Next() {
        if (hasMoreElements())
            return (Variant) nextElement();
        return null;
    }

    /**
     * @param receiverArray
     * @return don't know what the int is that is returned, help!
     */
    public native int Next(Variant[] receiverArray);

    /**
     * @param count
     */
    public native void Skip(int count);

    /**
     * 
     */
    public native void Reset();

    /**
     *  now private so only this object can asccess
     *  was: call this to explicitly release the com object before gc
     * 
     */
    private native void release();

    /*
     *  (non-Javadoc)
     * @see java.lang.Object#finalize()
     */
    protected void finalize() 
    {
        safeRelease();
    }
    
    /*
     *  (non-Javadoc)
     * @see com.jacob.com.JacobObject#safeRelease()
     */
    public void safeRelease()
    {
        super.safeRelease();
        if (m_pIEnumVARIANT != 0){
            this.release();
            m_pIEnumVARIANT = 0;
        } else {
            // looks like a double release
            if (isDebugEnabled()){debug(this.getClass().getName()+":"+this.hashCode()+" double release");}
        }
    }
}