dertaggedobject.java

《移动Agent技术》一书的所有章节源代码。

package org.bouncycastle.asn1;

import java.io.*;

/**
 * DER TaggedObject - in ASN.1 nottation this is any object proceeded by
 * a [n] where n is some number - these are assume to follow the construction
 * rules (as with sequences).
 */
public class DERTaggedObject
    extends DERObject
{
    int             tagNo;
    boolean         empty = false;
    boolean         explicit = true;
    DEREncodable    obj = null;

    /**
     * This creates an empty tagged object of tagNo (ie. zero length).
     *
     * @param tagNo the tag number for this object.
     */
    public DERTaggedObject(
        int     tagNo)
    {
        this.explicit = true;
        this.tagNo = tagNo;
        this.empty = true; 
    }

    /**
     * This creates an empty tagged object of tagNo (ie. zero length).
     *
     * @param tagNo the tag number for this object.
     */
    public DERTaggedObject(
        boolean explicit,
        int     tagNo)
    {
        this.explicit = explicit;
        this.tagNo = tagNo;
        this.empty = true; 
    }

    /**
     * @param tagNo the tag number for this object.
     * @param obj the tagged object.
     */
    public DERTaggedObject(
        int             tagNo,
        DEREncodable    obj)
    {
        this.explicit = true;
        this.tagNo = tagNo;
        this.obj = obj;
    }

    /**
     * @param explicit true if the object is explicitly tagged.
     * @param tagNo the tag number for this object.
     * @param obj the tagged object.
     */
    public DERTaggedObject(
        boolean         explicit,
        int             tagNo,
        DEREncodable    obj)
    {
        this.explicit = explicit;
        this.tagNo = tagNo;
        this.obj = obj;
    }

    public int getTagNo()
    {
        return tagNo;
    }

    public boolean isExplicit()
    {
        return explicit;
    }

    public boolean isEmpty()
    {
        return empty;
    }

    public DERObject getObject()
    {
        return obj.getDERObject();
    }

    void encode(
        DEROutputStream  out)
        throws IOException
    {
        if (!empty)
        {
            ByteArrayOutputStream   bOut = new ByteArrayOutputStream();
            DEROutputStream         dOut = new DEROutputStream(bOut);

            dOut.writeObject(obj);
            dOut.close();

            byte[]  bytes = bOut.toByteArray();

            if (explicit)
            {
                out.writeEncoded(CONSTRUCTED | TAGGED | tagNo, bOut.toByteArray());
            }
            else
            {
                //
                // need to mark constructed types...
                //
                if ((bytes[0] & CONSTRUCTED) != 0)
                {
                    bytes[0] = (byte)(CONSTRUCTED | TAGGED | tagNo);
                }
                else
                {
                    bytes[0] = (byte)(TAGGED | tagNo);
                }

                out.write(bytes);
            }
        }
        else
        {
            out.writeEncoded(CONSTRUCTED | TAGGED | tagNo, new byte[0]);
        }
    }
}