xmlproperties.java

java与模式 一书的源码

package com.javapatterns.xmlproperties;

import org.xml.sax.DocumentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.Locator;
import org.xml.sax.AttributeList;
import org.xml.sax.Parser;
import org.xml.sax.InputSource;

import java.io.IOException;
import java.io.OutputStream;
import java.io.InputStream;
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.File;
import java.io.PrintWriter;
import java.util.Properties;
import java.util.Enumeration;


/**
 * The <code>Properties</code> class represents a persistent set of 
 * properties. The <code>Properties</code> can be saved to a stream or 
 * loaded from a stream. Each key and its corresponding value in the 
 * property list is a string.
 * <p>
 * A property list can contain another property list as its "defaults"; this 
 * second property list is searched if the property key is not found in the
 * original property list. Because Properties inherits from Hashtable, the 
 * put and putAll methods can be applied to a Properties object. Their use
 *  is strongly discouraged as they allow the caller to insert entries whose
 * keys or values are not Strings. The setProperty method should be used 
 * instead. If the store or save method is called on a "compromised" 
 * Properties object that contains a non-String key or value, the call will 
 * fail.
 * <p>
 * This is a special implementation for XML :
 * <pre>
 *   &lt;properties>
 *      &lt;key name="My_key1">My_Value1&lt;/key>
 *      &lt;key name="My_key2">My_Value2&lt;/key>
 *   &lt;/properties>
 * </pre>
 */
public class XMLProperties extends Properties
{
	XMLParser p = null;

    /**
     * Reads a property list from an input stream.
     * @param      in   the input stream.
     * @exception  IOException  if an error occurred when reading from the
     * input stream.
     * @since   JDK1.0
     */
    public synchronized void load(InputStream in) throws IOException
    {
		try
        {
		    p = new XMLParser(in, this);
		}
        catch (SAXException e)
        {
		    throw new IOException(e.getMessage());
		}
    }

    /**
     * Reads a property list from an input stream. This method try to load
     * properties with super.load() if the XMLParser failed. Use this method
     * to translate an Property set to an XML Property set.
     * @param      file the properties file.
     * @exception  IOException  if an error occurred when reading from the
     * input stream.
     * @since   JDK1.0
     */
    public synchronized void load(File file) throws SAXException, IOException
    {
//        System.out.println("File: " + file);
//        System.out.println("File exists " + file.exists());

		InputStream in = new BufferedInputStream(new FileInputStream(file));
		XMLParser p = null;
		try
        {
		    p = new XMLParser(in, this);
		}
        catch (SAXException e)
        {
            System.out.println(e);
            throw e;
		}
    }

    /**
     * Calls the <code>store(OutputStream out, String header)</code> method
     * and suppresses IOExceptions that were thrown.
     *
     * @deprecated This method does not throw an IOException if an I/O error
     * occurs while saving the property list.  As of JDK 1.2, the preferred
     * way to save a properties list is via the <code>store(OutputStream out,
     * String header)</code> method.
     *
     * @param   out      an output stream.
     * @param   header   a description of the property list.
     * @exception  ClassCastException  if this <code>Properties</code> object
     * contains any keys or values that are not <code>Strings</code>.
     */
    public synchronized void save(OutputStream out, String header)
    {
		try
        {
		    store(out, header);
		}
        catch (IOException ex)
        {
		    ex.printStackTrace();
		}
    }

    /**
     * Writes this property list (key and element pairs) in this
     * <code>Properties</code> table to the output stream in a format suitable
     * for loading into a <code>Properties</code> table using the
     * <code>load</code> method.
     * <p>
     * After the entries have been written, the output stream is flushed.  The
     * output stream remains open after this method returns.
     *
     * @param   out      an output stream.
     * @param   header   a description of the property list.
     * @exception  ClassCastException  if this <code>Properties</code> object
     * contains any keys or values that are not <code>Strings</code>.
     */
    public synchronized void store(OutputStream out, String header) 
	throws IOException
    {
		PrintWriter wout = new PrintWriter(out);
		    wout.println("<?xml version='1.0'?>");
		if (header != null)
        {
		    wout.println("<!--" + header + "-->");
		}
		
		wout.print("<properties>");
		for (Enumeration e = keys() ; e.hasMoreElements() ;)
        {
		    String key = (String)e.nextElement();
		    String val = (String)get(key);
		    wout.print("\n <key name=\"" + key + "\">");
		    wout.print(encode(val));
		    wout.print("</key>");
		}
		wout.print("\n</properties>");
		wout.flush();
    }

    protected StringBuffer encode(String string)
    {
		int          len    = string.length();
		StringBuffer buffer = new StringBuffer(len);
		char         c;
	
		for (int i = 0 ; i < len ; i++)
        {
		    switch (c = string.charAt(i)) 
			{
			case '&':
			    buffer.append("&amp;");
			    break;
			case '<':
			    buffer.append("&lt;");
			    break;
			case '>':
			    buffer.append("&gt;");
			    break;
			default:
			    buffer.append(c);
			}
		}
	
		return buffer;
    }

    /**
     * Creates an empty property list with no default values.
     */
    public XMLProperties()
    {
		super();
    }

    /**
     * Creates an empty property list with the specified defaults.
     *
     * @param   defaults   the defaults.
     */
    public XMLProperties(Properties defaults)
    {
		super(defaults);
    }
}