geometry.java

postGIS是一个能够使用postSQL数据库来管理GIS数据的小程序,充分发挥了该数据库的空间管理功能,非常有用哦

/*
 * Geometry.java
 * 
 * PostGIS extension for PostgreSQL JDBC driver - geometry model
 * 
 * (C) 2004 Paul Ramsey, [e-mail]
 * 
 * (C) 2005 Markus Schaber, [e-mail]
 * 
 * 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.
 * 
 * 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.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA or visit the web at
 * http://www.gnu.org.
 * 
 * $Id: Geometry.java 2495 2006-10-02 15:58:43Z mschaber $
 */

package org.postgis;

import java.io.Serializable;

/** The base class of all geometries */
public abstract class Geometry implements Serializable {
    /* JDK 1.5 Serialization */
    private static final long serialVersionUID = 0x100;

    // OpenGIS Geometry types as defined in the OGC WKB Spec
    // (May we replace this with an ENUM as soon as JDK 1.5
    // has gained widespread usage?)

    /** Fake type for linear ring */
    public static final int LINEARRING = 0;
    /**
     * The OGIS geometry type number for points.
     */
    public static final int POINT = 1;

    /**
     * The OGIS geometry type number for lines.
     */
    public static final int LINESTRING = 2;

    /**
     * The OGIS geometry type number for polygons.
     */
    public static final int POLYGON = 3;

    /**
     * The OGIS geometry type number for aggregate points.
     */
    public static final int MULTIPOINT = 4;

    /**
     * The OGIS geometry type number for aggregate lines.
     */
    public static final int MULTILINESTRING = 5;

    /**
     * The OGIS geometry type number for aggregate polygons.
     */
    public static final int MULTIPOLYGON = 6;

    /**
     * The OGIS geometry type number for feature collections.
     */
    public static final int GEOMETRYCOLLECTION = 7;

    public static final String[] ALLTYPES = new String[]{
        "", // internally used LinearRing does not have any text in front of it
        "POINT",
        "LINESTRING",
        "POLYGON",
        "MULTIPOINT",
        "MULTILINESTRING",
        "MULTIPOLYGON",
        "GEOMETRYCOLLECTION"};

    /**
     * The Text representations of the geometry types
     */
    public static String getTypeString(int type) {
        if (type >= 0 && type <= 7) {
            return ALLTYPES[type];
        } else {
            throw new IllegalArgumentException("Unknown Geometry type" + type);
        }
    }

    // Properties common to all geometries
    /**
     * The dimensionality of this feature (2,3)
     */
    public int dimension;

    /**
     * Do we have a measure (4th dimension)
     */
    public boolean haveMeasure = false;

    /**
     * The OGIS geometry type of this feature. this is final as it never
     * changes, it is bound to the subclass of the instance.
     */
    public final int type;

    /**
     * The spacial reference system id of this geometry, default (no srid) is -1
     */
    public int srid = -1;

    /**
     * Constructor for subclasses
     * 
     * @param type has to be given by all subclasses.
     */
    protected Geometry(int type) {
        this.type = type;
    }

    /**
     * java.lang.Object hashCode implementation
     */
    public int hashCode() {
        return dimension | (type * 4) | (srid * 32);
    }

    /**
     * java.lang.Object equals implementation
     */
    public boolean equals(Object other) {
        return (other != null) && (other instanceof Geometry) && equals((Geometry) other);
    }

    /**
     * geometry specific equals implementation - only defined for non-null
     * values
     */
    public boolean equals(Geometry other) {
        return (other != null) 
                && (this.dimension == other.dimension)
                && (this.type == other.type)
                && (this.srid == other.srid) 
                && (this.haveMeasure == other.haveMeasure) 
                && other.getClass().equals(this.getClass()) 
                && this.equalsintern(other);
    }

    /**
     * Whether test coordinates for geometry - subclass specific code
     * 
     * Implementors can assume that dimensin, type, srid and haveMeasure are
     * equal, other != null and other is the same subclass.
     */
    protected abstract boolean equalsintern(Geometry other);

    /**
     * Return the number of Points of the geometry
     */
    public abstract int numPoints();

    /**
     * Get the nth Point of the geometry
     * 
     * @param n the index of the point, from 0 to numPoints()-1;
     * @throws ArrayIndexOutOfBoundsException in case of an emtpy geometry or
     *             bad index.
     */
    public abstract Point getPoint(int n);

    /**
     * Same as getPoint(0);
     */
    public abstract Point getFirstPoint();

    /**
     * Same as getPoint(numPoints()-1);
     */
    public abstract Point getLastPoint();

    /**
     * The OGIS geometry type number of this geometry.
     */
    public int getType() {
        return this.type;
    }

    /**
     * Return the Type as String
     */
    public String getTypeString() {
        return getTypeString(this.type);
    }

    /** Returns whether we have a measure */
    public boolean isMeasured() {
        return haveMeasure;
    }

    /**
     * Queries the number of geometric dimensions of this geometry. This does
     * not include measures, as opposed to the server.
     * 
     * @return The dimensionality (eg, 2D or 3D) of this geometry.
     */
    public int getDimension() {
        return this.dimension;
    }

    /**
     * The OGIS geometry type number of this geometry.
     */
    public int getSrid() {
        return this.srid;
    }

    /**
     * Recursively sets the srid on this geometry and all contained
     * subgeometries
     */
    public void setSrid(int srid) {
        this.srid = srid;
    }

    public String toString() {
        StringBuffer sb = new StringBuffer();
        if (srid != -1) {
            sb.append("SRID=");
            sb.append(srid);
            sb.append(';');
        }
        outerWKT(sb, true);
        return sb.toString();
    }

    /**
     * Render the WKT version of this Geometry (without SRID) into the given
     * StringBuffer.
     */
    public void outerWKT(StringBuffer sb, boolean putM) {
        sb.append(getTypeString());
        if (putM && haveMeasure && dimension == 2) {
            sb.append('M');
        }
        mediumWKT(sb);
    }

    public final void outerWKT(StringBuffer sb) {
        outerWKT(sb, true);
    }

    /**
     * Render the WKT without the type name, but including the brackets into the
     * StringBuffer
     */
    protected void mediumWKT(StringBuffer sb) {
        sb.append('(');
        innerWKT(sb);
        sb.append(')');
    }

    /**
     * Render the "inner" part of the WKT (inside the brackets) into the
     * StringBuffer.
     */
    protected abstract void innerWKT(StringBuffer SB);

    /**
     * backwards compatibility method
     */
    public String getValue() {
        StringBuffer sb = new StringBuffer();
        mediumWKT(sb);
        return sb.toString();
    }

    /**
     * Do some internal consistency checks on the geometry.
     * 
     * Currently, all Geometries must have a valid dimension (2 or 3) and a
     * valid type. 2-dimensional Points must have Z=0.0, as well as non-measured
     * Points must have m=0.0. Composed geometries must have all equal SRID,
     * dimensionality and measures, as well as that they do not contain NULL or
     * inconsistent subgeometries.
     * 
     * BinaryParser and WKTParser should only generate consistent geometries.
     * BinaryWriter may produce invalid results on inconsistent geometries.
     * 
     * @return true if all checks are passed.
     */
    public boolean checkConsistency() {
        return (dimension >= 2 && dimension <= 3) && (type >= 0 && type <= 7);
    }

    /**
     * Splits the SRID=4711; part of a EWKT rep if present and sets the srid.
     * 
     * @returns value without the SRID=4711; part
     */
    protected String initSRID(String value) {
        value = value.trim();
        if (value.startsWith("SRID=")) {
            int index = value.indexOf(';', 5); // sridprefix length is 5
            if (index == -1) {
                throw new IllegalArgumentException(
                        "Error parsing Geometry - SRID not delimited with ';' ");
            } else {
                this.srid = Integer.parseInt(value.substring(5, index));
                return value.substring(index + 1).trim();
            }
        } else {
            return value;
        }
    }
}