/*
** Released into the public domain.
** PROVIDED AS-IS.  NO WARRANTY.  USE AT YOUR OWN RISK.
*/

import java.applet.*;
import java.awt.*;

/**
** Identify platform using system properties, displayed in Labels.
*/
public class SimpleID
  extends Applet
{
	/**
	** As an Applet, only do minimal amount in constructor,
	** since no AppletStub assigned yet, hence no parameters are available.
	*/
	public 
	SimpleID() 
	{  super();  }


	/** 
	** Applet life-cycle method. 
	** Builds its own content.
	*/
	public void
	init()
	{
		// Get identifiers for JVM and OS, with overrides given by applet's params.
		String jvm = getProp( "java.version", "?" );
		jvm = getProp( "java.runtime.version", jvm );
		String os = getProp( "os.name", "OS" );
		String osv = getProp( "os.version", "?" );
		String arch = getProp( "os.arch", "?" );

		// Arrange content within applet.
		setBackground( getColor( "bgcolor", 0xFFFFFF ) );
		setLayout( new FlowLayout() );  // default is CENTER, 5x5 gaps
		add( platform( jvm, os, osv, arch ) );

		// Minor voodoo mentioned in Sun's Applet Tutorial (plain-AWT, not Swing)
		this.validate();
	}

	/** Returns a Component with platform-identifying info. */
	protected Component
	platform( String jvm, String os, String osv, String arch )
	{
		Panel holder = new Panel( new GridLayout( 0, 1, 0, 0 ) ); // rows, cols, hgap, vgap

		holder.add( new Label( "Java: " + jvm, Label.CENTER ) );
		holder.add( new Label( os + ": " + osv + " " + arch, Label.CENTER ) );

		return ( holder );
	}



	/** Get a value from Applet param, or from System properties. */
	public Color
	getColor( String propName, int fallbackRGB )
	{  return ( new Color( getInteger( propName, fallbackRGB ).intValue() ) );  }


	/** Get a value from Applet param, or from System properties. */
	public Integer
	getInteger( String propName, int fallback )
	{
		String value = getProp( propName );
		if ( value != null )
		{
			try
			{  return Integer.decode( value.trim() );  }
			catch ( NumberFormatException fallsThru )
			{  ;  }
		}
		return ( new Integer( fallback ) );
	}

	/** Get a value, or use fallback. */
	public String
	getProp( String propName, String fallback )
	{
		String value = getProp( propName );
		if ( value != null )
			return ( value );

		return ( fallback );
	}

	/**
	** Get a value from applet parameters, or from System properties, or null.
	** Protected with try/catch, so a properties security-exception returns null.
	*/
	public String
	getProp( String propName )
	{
		String value = getParameter( propName );
		if ( value != null )
			return ( value );

		try
		{  return ( System.getProperty( propName ) );  }
		catch ( SecurityException fallsThru )
		{  ;  }

		return ( null );
	}

}