tag.java

SMPP（点到点短消息协议）的java实现

            if (tagTable.containsKey(this.tag)) {
                throw new TagDefinedException(tag, "Tag 0x"
                        + Integer.toHexString(tag) + " is already defined.");
            }

            tagTable.put(this.tag, this);
        }
    }

    /**
     * Get an <code>Encoder</code> for a particular Java type.
     * 
     * @param type
     *            The Java type to get an encoder for.
     * @return The encoder/decoder for Java type <code>type</code>.
     */
    private Encoder getEncoderForType(Class type) {
        Encoder encoder;
        
        // If type is null and encoder is null, this is a "no value" tlv type.
        if (type == null) {
            encoder = new NullEncoder();
        } else if (java.lang.Number.class.isAssignableFrom(type)) {
            encoder = new NumberEncoder();
        } else if (java.lang.String.class.isAssignableFrom(type)) {
            encoder = new StringEncoder();
        } else if (java.util.BitSet.class.isAssignableFrom(type)) {
            encoder = new BitmaskEncoder();
        } else if (byte[].class.isAssignableFrom(type)) {
            encoder = new OctetEncoder();
        } else {
            throw new NoEncoderException(type, "No encoder for class type "
                    + type.getName());
        }
        return encoder;
    }

    /**
     * Get the integer value of this tag.
     * 
     * @return the integer value of this tag.
     */
    public int intValue() {
        return tag.intValue();
    }

    /**
     * Get the allowed length of a value of this tag type.
     * 
     * @return The allowed length, or the maximum length if a range is set.
     */
    public int getLength() {
        return maxLength < 0 ? minLength : maxLength;
    }

    /**
     * Get the minimum length of a value of this tag type.
     * 
     * @return the minimum length of a value of this tag type.
     */
    public int getMinLength() {
        return minLength;
    }

    /**
     * Get the maximum length of a value of this tag type.
     * 
     * @return the maximum length of a value of this tag type.
     */
    public int getMaxLength() {
        return maxLength;
    }

    /**
     * Get the Java type of values of this tag type.
     * 
     * @return the Java type of values of this tag type.
     */
    public Class getType() {
        return type;
    }

    /**
     * Test for equality. Two tags are equal if their integer values are
     * equivalent.
     * 
     * @return true if <code>obj</code> is Tag and has the same tag value.
     */
    public boolean equals(Object obj) {
        if (obj instanceof Tag) {
            return ((Tag) obj).tag.equals(this.tag);
        } else {
            return false;
        }
    }

    /**
     * Test for equality against an integer.
     * 
     * @return true if this Tag's integer value is equal to <code>tag</code>.
     */
    public boolean equals(int tag) {
        return tag == this.tag.intValue();
    }

    /**
     * Get the hashCode for this Tag. The hashCode for a Tag is the same as:
     * <br>
     * <code>new Integer(tag.tagValue()).hashCode()</code>
     * 
     * @return A hash code for this tag.
     */
    public int hashCode() {
        return tag.hashCode();
    }

    /**
     * Convert this tag to a String. This returns a decimal representation of
     * the tag's integer value in a String.
     * 
     * @return This tag's string value.
     */
    public String toString() {
        return tag.toString();
    }

    /**
     * Convert this tag to a String. This returns a hex representation of the
     * tag's integer value in a String.
     * 
     * @return This tag's hexadecimal representation.
     */
    public String toHexString() {
        return Integer.toHexString(tag.intValue());
    }

    /**
     * Get the encoder used to encode values of this tag type.
     * 
     * @return the encoder used to encode values of this tag type.
     */
    public Encoder getEncoder() {
        return encoder;
    }

    /**
     * Get the Tag object that represents tag <code>tagValue</code>. If the
     * tag is known then the static Tag object representing the tag is returned.
     * If the tag is not known, a fresh instance of Tag will be returned which
     * uses an octet-string type.
     * 
     * <p><b>WARNING</b> The behaviour of this method may change to returning
     * <code>null</code> for an undefined tag. It needs to be determined
     * which behaviour is the best.</p>
     * 
     * @return The Tag object representing the tag <code>tagValue</code>.
     *         Will never return <code>null</code>.
     */
    public static Tag getTag(int tagValue) {
        Tag t = (Tag) tagTable.get(new Integer(tagValue));
        if (t == null) {
            return Tag.defineTag(tagValue, byte[].class, null, -1, -1);
        } else {
            return t;
        }
    }

    /**
     * Define a new tag type which has a fixed length.
     * @param tagValue
     *            the integer value of the tag.
     * @param type
     *            the parameter type.
     * @param enc
     *            the encoder used to serialize and deserialize. This may be
     *            null to use the API's default internally defined encoders.
     * @param fixedSize
     *            the defined size of the parameter.
     * @throws ie.omk.smpp.message.tlv.TagDefinedException
     *             if an attempt is made to define a tag with a integer value
     *             equivalent to an already defined tag.
     * @see Encoder
     */
    public static Tag defineTag(int tagValue, Class type, Encoder enc,
            int fixedSize) throws TagDefinedException {
        return new Tag(tagValue, type, enc, fixedSize);
    }

    /**
     * Define a new tag type with minimum and maximum sizes.
     * @param tagValue
     *            the integer value of the tag.
     * @param type
     *            the parameter type.
     * @param enc
     *            the encoder used to serialize and deserialize. This may be
     *            null to use the API's default internally defined encoders.
     * @param minSize
     *            the minimum size of the parameter.
     * @param maxSize
     *            the maximum size of the parameter.
     * @throws ie.omk.smpp.message.tlv.TagDefinedException
     *             if an attempt is made to define a tag with a integer value
     *             equivalent to an already defined tag.
     * @see Encoder
     */
    public static Tag defineTag(int tagValue, Class type, Encoder enc,
            int minSize, int maxSize) throws TagDefinedException {
        return new Tag(tagValue, type, enc, minSize, maxSize);
    }

    /**
     * Determine if a tag is defined for a particular tag integer value. 
     * @param tagValue The integer value of the tag.
     * @return <code>true</code> if the tag is defined, <code>false</code>
     * otherwise.
     */
    public static boolean isTagDefined(int tagValue) {
        return tagTable.containsKey(new Integer(tagValue));
    }
    
    /**
     * Undefine a tag. This removes all knoweledge of this tag type from the
     * internal tables. If there is no such tag defined already, this method
     * will do nothing.
     * 
     * @param tag
     *            The tag to undefine. null if there was no tag defined already.
     * @return The Tag object that has been undefined.
     */
    public static Tag undefineTag(Tag tag) {
        if (tag == null) {
            return null;
        }
        synchronized (tagTable) {
            return (Tag) tagTable.remove(tag.tag);
        }
    }
}