dcwcolumninfo.java

openmap java写的开源数字地图程序. 用applet实现,可以像google map 那样放大缩小地图.

        case VPF_COLUMN_TEXT:
        case VPF_COLUMN_TEXTL1:
        case VPF_COLUMN_TEXTL3:
        case VPF_COLUMN_TEXTL2: //various text string types
            return numberOfElements;
        case VPF_COLUMN_FLOAT: //floats
            return 4;
        case VPF_COLUMN_DOUBLE: //doubles
            return 8;
        case VPF_COLUMN_SHORT: //shorts
            return 2;
        case VPF_COLUMN_INT: //ints
            return 4;
        case VPF_COLUMN_FLOAT_2COORD: //2-coord floats
            return numberOfElements * 8;
        case VPF_COLUMN_DOUBLE_2COORD: //2-coord doubles
            return numberOfElements * 16;
        case VPF_COLUMN_FLOAT_3COORD: //3-coord floats
            return numberOfElements * 12;
        case VPF_COLUMN_DOUBLE_3COORD: //3-coord doubles
            return numberOfElements * 24;
        case VPF_COLUMN_DATE: //dates
            return 20;
        case VPF_COLUMN_NULL: //nulls
            return 0;
        case VPF_COLUMN_TRIPLET: //cross-tile identifiers
            return -1; //variable length
        default: {
            throw new FormatException("Unknown field type: " + fieldType);
        }
        }
        //unreached
    }

    /**
     * get the name of the column
     * 
     * @return the name of the column
     */
    public String getColumnName() {
        return columnName;
    }

    /**
     * get the VPF datatype of the column
     * 
     * @return the VPF datatype
     */
    public char getFieldType() {
        return fieldType;
    }

    /**
     * get the number of elements
     * 
     * @return the number of elements
     */
    public int getNumberOfElements() {
        return numberOfElements;
    }

    /**
     * get the VPF key type (one of VPF_COLUMN_PRIMARY_KEY,
     * VPF_COLUMN_FOREIGN_KEY, or VPF_COLUMN_NON_KEY)
     * 
     * @return the vpf key type
     */
    public char getKeyType() {
        return keyType;
    }

    /**
     * Return <code>true</code> if this column is a primary key. For
     * any valid column, exactly one of isPrimaryKey, isForeignKey and
     * isNonKey will be <code>true</code>.
     * 
     * @return true for a primary key, false otherwise.
     * @see #isForeignKey()
     * @see #isNonKey()
     */
    public boolean isPrimaryKey() {
        return (keyType == VPF_COLUMN_PRIMARY_KEY);
    }

    /**
     * Return <code>true</code> if this column is a foreign key. For
     * any valid column, exactly one of isPrimaryKey, isForeignKey and
     * isNonKey will be <code>true</code>.
     * 
     * @return true for a foreign key, false otherwise.
     * @see #isPrimaryKey()
     * @see #isNonKey()
     */
    public boolean isForeignKey() {
        return (keyType == VPF_COLUMN_FOREIGN_KEY);
    }

    /**
     * Return <code>true</code> if this column is not a key column.
     * For any valid column, exactly one of isPrimaryKey, isForeignKey
     * and isNonKey will be <code>true</code>.
     * 
     * @return false for a primary or foreign key, true otherwise.
     * @see #isForeignKey()
     * @see #isPrimaryKey()
     */
    public boolean isNonKey() {
        return (keyType == VPF_COLUMN_NON_KEY);
    }

    /**
     * Get the column description
     * 
     * @return the column description (possibly <code>null</code>)
     */
    public String getColumnDescription() {
        return columnDescription;
    }

    /**
     * Get the name of the value description table
     * 
     * @return the name of the value description table (possibly
     *         <code>null</code>). The same as getVDT()
     * @see #getVDT()
     */
    public String getValueDescriptionTable() {
        return valueDescriptionTable;
    }

    /**
     * Get the name of the value description table
     * 
     * @return the name of the value description table (possibly
     *         <code>null</code>). The same as
     *         getValueDescriptionTable
     * @see #getValueDescriptionTable()
     */
    public String getVDT() {
        return valueDescriptionTable;
    }

    /**
     * get the name of the thematic index
     * 
     * @return the thematic index name (possibly <code>null</code>)
     */
    public String getThematicIndexName() {
        return thematicIndexName;
    }

    /**
     * get the name of the narrative table
     * 
     * @return the name of the narrative table (possibly
     *         <code>null</code>)
     */
    public String getNarrativeTable() {
        return narrativeTable;
    }

    /**
     * Read an element of the type specified by the column
     * 
     * @return the value read from the input file
     * @exception EOFException an end-of-file was encountered before
     *            reading any of the field
     * @exception FormatException some data-consistency check failed
     *            while reading the data, or an end-of-file condition
     *            popped up in the middle of reading a field (partial
     *            read)
     */
    public Object parseField(BinaryFile inputFile) throws EOFException,
            FormatException {
        // See table 56, p 79 of MIL-STD-600006 (1992 VPF Standard)
        // See table 10, p 51 of MIL-STD-2407 (1996 VPF Standard
        // supercedes 600006)
        boolean haveElements = (numberOfElements != -1);
        int numels = numberOfElements;

        switch (fieldType) {
        case VPF_COLUMN_TEXT: {
            if (!haveElements) {//Variable length string
                numels = inputFile.readInteger();
            }
            if (numels == 0) {
                return "";
            }
            String s = inputFile.readFixedLengthString(numels);
            if (haveElements) {//Fixed Length Strings loose trailing
                               // whitespace
                s = s.trim();
            }
            return s;
        }
        case VPF_COLUMN_TEXTL1: {
            if (!haveElements) {//Variable length string
                numels = inputFile.readInteger();
            }
            if (numels == 0) {
                return "";
            }
            byte[] str = inputFile.readBytes(numels, false);
            try {
                String s = new String(str, "ISO8859_1");
                if (haveElements) {//Fixed Length Strings loose
                                   // trailing whitespace
                    s = s.trim();
                }
                return s;
            } catch (java.io.UnsupportedEncodingException uee) {
                return str;
            }
        }
        case VPF_COLUMN_TEXTL2:
        case VPF_COLUMN_TEXTL3: {
            if (!haveElements) {//Variable length string
                numels = inputFile.readInteger();
            }
            if (numels == 0) {
                return new byte[0];
            }
            return inputFile.readBytes(numels, false);
        }
        case VPF_COLUMN_FLOAT: {
            return new Float(inputFile.readFloat());
        }
        case VPF_COLUMN_DOUBLE: {
            return new Double(inputFile.readDouble());
        }
        case VPF_COLUMN_SHORT: {
            return new Short(inputFile.readShort());
        }
        case VPF_COLUMN_INT: {
            return new Integer(inputFile.readInteger());
        }
        case VPF_COLUMN_FLOAT_2COORD: { //2-coord floats
            if (!haveElements) {
                numels = inputFile.readInteger();
            }
            return new CoordFloatString(numels, 2, inputFile);
        }
        case VPF_COLUMN_DOUBLE_2COORD: { //2-coord doubles
            if (!haveElements) {
                numels = inputFile.readInteger();
            }
            return new CoordDoubleString(numels, 2, inputFile);
        }
        case VPF_COLUMN_FLOAT_3COORD: { //3-coord floats
            if (!haveElements) {
                numels = inputFile.readInteger();
            }
            return new CoordFloatString(numels, 3, inputFile);
        }
        case VPF_COLUMN_DOUBLE_3COORD: { //3-coord doubles
            if (!haveElements) {
                numels = inputFile.readInteger();
            }
            return new CoordDoubleString(numels, 3, inputFile);
        }
        case VPF_COLUMN_DATE: {
            inputFile.readBytes(20, false);
            return "[skipped date]";
        }
        case VPF_COLUMN_NULL: {
            return "[Null Field Type]";
        }
        case VPF_COLUMN_TRIPLET: {
            return new DcwCrossTileID(inputFile);
        }
        default: {
            throw new FormatException("Unknown field type: " + fieldType);
        }
        }
        //unreached
    }

    /**
     * produce a nice printed version of all our contained information
     * 
     * @return a nice little string
     */
    public String toString() {
        StringBuffer output = new StringBuffer();
        output.append(columnName + " " + fieldType + " ");
        output.append(numberOfElements).append(" ");
        output.append(keyType).append(" ");
        output.append(columnDescription + " " + valueDescriptionTable + " ");
        output.append(thematicIndexName + " " + narrativeTable);
        return output.toString();
    }
}