directory.java

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     * @return the tag's value as an array of Strings
     * @throws MetadataException if the tag has not been set or cannot be represented
     *         as a String[]
     */
    public String[] getStringArray(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof String[]) {
            return (String[])o;
        } else if (o instanceof String) {
            String[] strings = {(String)o};
            return strings;
        } else if (o instanceof int[]) {
            int[] ints = (int[])o;
            String[] strings = new String[ints.length];
            for (int i = 0; i<strings.length; i++) {
                strings[i] = Integer.toString(ints[i]);
            }
            return strings;
        } else if (o instanceof byte[]) {
            byte[] bytes = (byte[])o;
            String[] strings = new String[bytes.length];
            for (int i = 0; i<strings.length; i++) {
                strings[i] = Byte.toString(bytes[i]);
            }
            return strings;
        } else if (o instanceof Rational[]) {
            Rational[] rationals = (Rational[])o;
            String[] strings = new String[rationals.length];
            for (int i = 0; i<strings.length; i++) {
                strings[i] = rationals[i].toSimpleString(false);
            }
            return strings;
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to an String array.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Gets the specified tag's value as an int array, if possible.  Only supported
     * where the tag is set as String, int[], byte[] or Rational[].
     * @param tagType the tag identifier
     * @return the tag's value as an int array
     * @throws MetadataException if the tag has not been set, or cannot be converted to
     *         an int array
     */
    public int[] getIntArray(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof Rational[]) {
            Rational[] rationals = (Rational[])o;
            int[] ints = new int[rationals.length];
            for (int i = 0; i<ints.length; i++) {
                ints[i] = rationals[i].intValue();
            }
            return ints;
        } else if (o instanceof int[]) {
            return (int[])o;
        } else if (o instanceof byte[]) {
            byte[] bytes = (byte[])o;
            int[] ints = new int[bytes.length];
            for (int i = 0; i<bytes.length; i++) {
                byte b = bytes[i];
                ints[i] = b;
            }
            return ints;
        } else if (o instanceof String) {
            String str = (String)o;
            int[] ints = new int[str.length()];
            for (int i = 0; i<str.length(); i++) {
                ints[i] = str.charAt(i);
            }
            return ints;
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to an int array.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Gets the specified tag's value as an byte array, if possible.  Only supported
     * where the tag is set as String, int[], byte[] or Rational[].
     * @param tagType the tag identifier
     * @return the tag's value as a byte array
     * @throws MetadataException if the tag has not been set, or cannot be converted to
     *         a byte array
     */
    public byte[] getByteArray(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof Rational[]) {
            Rational[] rationals = (Rational[])o;
            byte[] bytes = new byte[rationals.length];
            for (int i = 0; i<bytes.length; i++) {
                bytes[i] = rationals[i].byteValue();
            }
            return bytes;
        } else if (o instanceof byte[]) {
            return (byte[])o;
        } else if (o instanceof int[]) {
            int[] ints = (int[])o;
            byte[] bytes = new byte[ints.length];
            for (int i = 0; i<ints.length; i++) {
                bytes[i] = (byte)ints[i];
            }
            return bytes;
        } else if (o instanceof String) {
            String str = (String)o;
            byte[] bytes = new byte[str.length()];
            for (int i = 0; i<str.length(); i++) {
                bytes[i] = (byte)str.charAt(i);
            }
            return bytes;
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a byte array.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Returns the specified tag's value as a double, if possible.
     */
    public double getDouble(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof String) {
            try {
                return Double.parseDouble((String)o);
            } catch (NumberFormatException nfe) {
                throw new MetadataException("unable to parse string " + o + " as a double", nfe);
            }
        } else if (o instanceof Number) {
            return ((Number)o).doubleValue();
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a double.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Returns the specified tag's value as a float, if possible.
     */
    public float getFloat(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof String) {
            try {
                return Float.parseFloat((String)o);
            } catch (NumberFormatException nfe) {
                throw new MetadataException("unable to parse string " + o + " as a float", nfe);
            }
        } else if (o instanceof Number) {
            return ((Number)o).floatValue();
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a float.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Returns the specified tag's value as a long, if possible.
     */
    public long getLong(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof String) {
            try {
                return Long.parseLong((String)o);
            } catch (NumberFormatException nfe) {
                throw new MetadataException("unable to parse string " + o + " as a long", nfe);
            }
        } else if (o instanceof Number) {
            return ((Number)o).longValue();
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a long.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Returns the specified tag's value as a boolean, if possible.
     */
    public boolean getBoolean(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof Boolean) {
            return ((Boolean)o).booleanValue();
        } else if (o instanceof String) {
            try {
                return Boolean.getBoolean((String)o);
            } catch (NumberFormatException nfe) {
                throw new MetadataException("unable to parse string " + o + " as a boolean", nfe);
            }
        } else if (o instanceof Number) {
            return (((Number)o).doubleValue()!=0);
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a boolean.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Returns the specified tag's value as a java.util.Date, if possible.
     */
    public java.util.Date getDate(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof java.util.Date) {
            return (java.util.Date)o;
        } else if (o instanceof String) {
            // add new dateformat strings to make this method even smarter
            // so far, this seems to cover all known date strings
            // (for example, AM and PM strings are not supported...)
            String datePatterns[] = {
                "yyyy:MM:dd HH:mm:ss",
                "yyyy:MM:dd HH:mm",
                "yyyy-MM-dd HH:mm:ss",
                "yyyy-MM-dd HH:mm"};
            String dateString = (String)o;
            for (int i = 0; i<datePatterns.length; i++) {
                try {
                    DateFormat parser = new java.text.SimpleDateFormat(datePatterns[i]);
                    return parser.parse(dateString);
                } catch (java.text.ParseException ex) {
                    // simply try the next pattern
                }
            }
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a java.util.Date.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Returns the specified tag's value as a Rational, if possible.
     */
    public Rational getRational(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof Rational) {
            return (Rational)o;
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a Rational.  It is of type '" + o.getClass() + "'.");
    }

    public Rational[] getRationalArray(int tagType) throws MetadataException
    {
        Object o = getObject(tagType);
        if (o==null) {
            throw new MetadataException("Tag " + getTagName(tagType) + " has not been set -- check using containsTag() first");
        } else if (o instanceof Rational[]) {
            return (Rational[])o;
        }
        throw new MetadataException("Tag '" + tagType + "' cannot be cast to a Rational array.  It is of type '" + o.getClass() + "'.");
    }

    /**
     * Returns the specified tag's value as a String.  This value is the 'raw' value.  A more presentable decoding
     * of this value may be obtained from the corresponding Descriptor.
     * @return the String reprensentation of the tag's value, or
     *         <code>null</code> if the tag hasn't been defined.
     */
    public String getString(int tagType)
    {
        Object o = getObject(tagType);
        if (o==null)
            return null;

        if (o instanceof Rational)
            return ((Rational)o).toSimpleString(true);

        if (o.getClass().isArray())
        {
            // handle arrays of objects and primitives
            int arrayLength = Array.getLength(o);
            // determine if this is an array of objects i.e. [Lcom.drew.blah
            boolean isObjectArray = o.getClass().toString().startsWith("class [L");
            StringBuffer sbuffer = new StringBuffer();
            for (int i = 0; i<arrayLength; i++)
            {
                if (i!=0)
                    sbuffer.append(' ');
                if (isObjectArray)
                    sbuffer.append(Array.get(o, i).toString());
                else
                    sbuffer.append(Array.getInt(o, i));
            }
            return sbuffer.toString();
        }

        return o.toString();
    }

    /**
     * Returns the object hashed for the particular tag type specified, if available.
     * @param tagType the tag type identifier
     * @return the tag's value as an Object if available, else null
     */
    public Object getObject(int tagType)
    {
        return _tagMap.get(new Integer(tagType));
    }

// OTHER METHODS

    /**
     * Returns the name of a specified tag as a String.
     * @param tagType the tag type identifier
     * @return the tag's name as a String
     */
    public String getTagName(int tagType)
    {
        Integer key = new Integer(tagType);
        HashMap nameMap = getTagNameMap();
        if (!nameMap.containsKey(key)) {
            String hex = Integer.toHexString(tagType);
            while (hex.length()<4) {
                hex = "0" + hex;
            }
            return "Unknown tag (0x" + hex + ")";
        }
        return (String)nameMap.get(key);
    }

    /**
     * Provides a description of a tag's value using the descriptor set by
     * <code>setDescriptor(Descriptor)</code>.
     * @param tagType the tag type identifier
     * @return the tag value's description as a String
     * @throws MetadataException if a descriptor hasn't been set, or if an error
     * occurs during calculation of the description within the Descriptor
     */
    public String getDescription(int tagType) throws MetadataException
    {
        if (_descriptor==null) {
            throw new MetadataException("a descriptor must be set using setDescriptor(...) before descriptions can be provided");
        }

        return _descriptor.getDescription(tagType);
    }
}