propertiesfilehorizonlookup.java

esri的ArcGIS Server超级学习模板程序（for java）

package com.esri.solutions.jitk.web.projection.horizon;

import java.io.IOException;
import java.util.Properties;

import org.apache.log4j.Logger;

import com.esri.adf.web.data.geometry.WebExtent;


/**
 * Concrete implementation of the {@link IHorizonLookup} interface.  This class will
 * go to a properties file containing horizon extent information.
 *
 * <p>
 * If no properties file is specified via the {@link #setPropertiesFile(String)} method,
 * the default properties file located on the classpath at "res/horizons.properties" will
 * be used.
 * </p>
 */
public class PropertiesFileHorizonLookup implements IHorizonLookup {
    /**
     * {@link Logger} used to log message for this class.
     */
    private static final Logger _logger = Logger.getLogger(PropertiesFileHorizonLookup.class);

    /**
     * Path to the properties file containing horizon extent information on the classpath.
     */
    private String _propertiesFile = "res/horizons.properties";

    /**
     * Spatial Reference horizon extents {@link Properties}.
     */
    private Properties _horizonProperties = null;

    /*
     * (non-Javadoc)
     * @see com.esri.solutions.jitk.common.projection.IHorizonLookup#lookup(int)
     */
    public WebExtent lookup(int spatialReferenceId) {
        
    	WebExtent horizon = null;

        try {
            if (_horizonProperties == null) {
                loadHorizons();
            }

            String horizonInfo = _horizonProperties.getProperty(String.valueOf(spatialReferenceId));

            if (horizonInfo == null) {
                _logger.warn("Horizon information not found for spatial reference ID: " + spatialReferenceId);
            
            } else {
            	String[] coords = horizonInfo.split(",");
            	horizon = new WebExtent(Double.valueOf(coords[0]), Double.valueOf(coords[1]), Double.valueOf(coords[2]), Double.valueOf(coords[3]));
            }
        
        } catch (IOException ex) {
            _logger.warn("An IOException occurred loading horizon properties file.", ex);
        }
        
        return horizon;
    }

    /**
     * Gets the classpath location of the properties file containing
     * the horizon extent information.
     *
     * @return {@link String} location of the properties file on the classpath.
     */
    public String getPropertiesFile() {
        return _propertiesFile;
    }

    /**
     * Sets the classpath location of the properties file containing
     * the horizon extent information.
     *
     * @param path {@link String} location of the properteis file on the classpath.
     */
    public void setPropertiesFile(String path) {
        _propertiesFile = path;

        // set to null so that it will be initialized with the new
        // properties file
        _horizonProperties = null;
    }

    /**
     * Loads the properties file stored in {@link #_propertiesFile} into a
     * {@link Properties} object.
     *
     * @throws IOException if an error occurs loading the properties file via
     *                         {@link Properties#load(java.io.InputStream)}.
     */
    private void loadHorizons() throws IOException {
        _horizonProperties = new Properties();
        _logger.debug("Loading horizon properties file: " + _propertiesFile);
        _horizonProperties.load(getClass().getClassLoader().getResourceAsStream(_propertiesFile));
    }
}