imageserviceelevationcalculator.java

esri的ArcGIS Server超级学习模板程序（for java）

package com.esri.solutions.jitk.services.elevation;

import com.esri.arcgisws.EnvelopeN;
import com.esri.arcgisws.GeoImageDescription;
import com.esri.arcgisws.ImageServerBindingStub;
import com.esri.arcgisws.ImageServiceInfo;

import com.esri.solutions.jitk.services.common.ServicesException;
import com.esri.solutions.jitk.services.elevation.Elevation;
import com.esri.solutions.jitk.services.elevation.ElevationCalculator;
import com.esri.solutions.jitk.services.elevation.Point;

import org.apache.axis.AxisFault;

import org.apache.log4j.Logger;

import java.net.MalformedURLException;
import java.net.URL;

import java.rmi.RemoteException;


public class ImageServiceElevationCalculator implements ElevationCalculator {
    private static final Logger _logger = Logger.getLogger(ImageServiceElevationCalculator.class);
    private String _endpoint = null;
    private ImageServerBindingStub _imageServer = null;

    public Elevation calculateElevation(Point pt)
        throws RemoteException, ServicesException {
        GeoImageDescription desc = new GeoImageDescription();
        ImageServiceInfo serviceInfo = null;
        EnvelopeN envelope = null;
        double deltax;
        double deltay;
        int pixelLocation;
        int littleEndianValue;
        double elevationMeters;
        Elevation elevation = null;
        byte[] image = null;

        _logger.debug("Requesting imager service information");
        serviceInfo = _imageServer.getServiceInfo();

        deltax = 2.5 * serviceInfo.getPixelSizeX();
        deltay = 2.5 * serviceInfo.getPixelSizeY();

        envelope = new EnvelopeN();

        envelope.setXMin(pt.getX() - deltax);
        envelope.setYMin(pt.getY() - deltay);
        envelope.setXMax(pt.getX() + deltax);
        envelope.setYMax(pt.getY() + deltay);

        desc.setExtent(envelope);
        desc.setWidth(5);
        desc.setHeight(5);

        _logger.debug("Invoking Image Service GetImage");
        image = _imageServer.getImage(desc);
        _logger.debug("Successfully invoked Image Service GetImage");

        // get the center pixel location of the 5x5 image
        // The location of the pixel at band b, row I, and column j can be 
        // calculated using the following formula.
        // pixel location = ((i*nCols+j)*nBands+b)*pixelsize(in bytes)
        pixelLocation = ((((2 * 5) + 2) * 1) + 1) * 4;

        byte[] pixelBytes = new byte[] {
                image[pixelLocation], image[pixelLocation + 1],
                image[pixelLocation + 2], image[pixelLocation + 3]
            };

        littleEndianValue = this.convertLittleEndianToInt(pixelBytes);
        _logger.debug("Little Endian value of pixel data: " +
            littleEndianValue);

        if (littleEndianValue != -1) {
            elevationMeters = littleEndianValue / 16384;

            elevation = new Elevation(elevationMeters, 2);

            _logger.debug("Successfully calculated elevation for point(" +
                pt.getX() + ", " + pt.getY() + "): " + elevationMeters);
        } else {
            // create empty elevation
            elevation = new Elevation();
        }

        return elevation;
    }

    public void setEndpoint(String endpoint) {
        if ((_endpoint == null) || !_endpoint.equalsIgnoreCase(endpoint)) {
            _endpoint = endpoint;

            _imageServer = this.createStub();
        }
    }

    private int convertLittleEndianToInt(byte[] littleEndian) {
        int value = 0;

        if (littleEndian == null) {
            throw new NullPointerException("Little Endian value cannot be null");
        }

        if (littleEndian.length != 4) {
            throw new IllegalArgumentException(
                "Invalid value - cannot convert Little Endian bytes to integer value");
        }

        value = ((littleEndian[3] << 24) + (littleEndian[2] << 16) +
            (littleEndian[1] << 8) + (littleEndian[0] << 0));

        return value;
    }

    private ImageServerBindingStub createStub() {
        ImageServerBindingStub stub = null;

        try {
            stub = new ImageServerBindingStub(new URL(_endpoint), null);
        } catch (AxisFault af) {
            _logger.warn(af);
        } catch (MalformedURLException ex) {
            _logger.warn(ex);
        }

        return stub;
    }
}