configuration.java

esri的ArcGIS Server超级学习模板程序（for java）

package com.esri.solutions.jitk.common.config;

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

import javax.faces.context.FacesContext;
import javax.servlet.ServletContext;

import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;

/**
 * Extends the Java Properties object in order to set the path to the properties resource so that
 * in can be used within a JSF bean management environment.  After the resource path is set, then
 * the properties object is loaded with the property values.
 */
public class Configuration extends Properties {

	private static final String ERROR_IOEXCEPTION = "Failed to initialize Configuration: cannot read configuration file.";
	private static final String ERROR_NULL_INPUT_STREAM = "Failed to initialize Configuration: cannot retrieve handle to configuration file";
	private static final String ERROR_NULL_SERVLET_CONTEXT = "Failed to initialize Configuration: cannot retrieve handle to ServletContext";
	private static final String ERROR_NULL_FACES_CONTEXT = "Failed to initialize Configuration: cannot retrieve handle to FacesContext";

	private static final Logger LOG = LogManager.getLogger(Configuration.class);
	
	private static final long serialVersionUID = 4817240692631653041L;
	
	
	private String m_resourcePath;
	
	/**
	 * Sets the ServletContext-relative path to the configuration property file.  The path is
	 * required and cannot be <code>null</code>.  This object will be initialized with the
	 * property values within the property file.  Other beans will call into this bean to get
	 * property values.  The property file must be resolvable via a call to 
	 * {@link ServletContext#getResourceAsStream(String)}.
	 * 
	 * @param path	ServletContext-relative path to configuration property file, cannot be <code>null</code>
	 * @throws NullPointerException		Thrown if the <code>path</code> argument is <code>null</code>.  
	 */
	public void setResourcePath (String path) {
		if (path == null) {
			throw new NullPointerException ();
		}
		
		m_resourcePath = path;
		init();
	}

	private void init() {
		
		if (m_resourcePath == null) {
			return;
		}
		
		FacesContext fCtx = FacesContext.getCurrentInstance();
		
		if (fCtx == null) {
			LOG.error(ERROR_NULL_FACES_CONTEXT);
			return;
		}
		
		if (!(fCtx.getExternalContext().getContext() instanceof ServletContext)) {
			LOG.error(ERROR_NULL_SERVLET_CONTEXT);
			return;
		}
		
		ServletContext sCtx = (ServletContext) fCtx.getExternalContext().getContext();
		
		InputStream in = sCtx.getResourceAsStream(m_resourcePath);
		if (in == null) {
			LOG.error(ERROR_NULL_INPUT_STREAM);
			return;
		}
		
		try {
			load(in);
		} catch (IOException e) {
			LOG.error(ERROR_IOEXCEPTION, e);
			return;
		}
	}

	
}