filesystemmodel.java

java jtable功能的实现

package view;

/*
 * %W% %E%
 *
 * Copyright 1997, 1998 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 * 
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer. 
 *   
 * - Redistribution in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution. 
 *   
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.  
 * 
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY
 * DAMAGES OR LIABILITIES SUFFERED BY LICENSEE AS A RESULT OF OR
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 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF 
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 * 
 * You acknowledge that this software is not designed, licensed or
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 */

import java.io.File;
import java.util.Date;

/**
 * FileSystemModel is a TreeTableModel representing a hierarchical file system.
 * Nodes in the FileSystemModel are FileNodes which, when they are directory
 * nodes, cache their children to avoid repeatedly querying the real file
 * system.
 * 
 * @version %I% %G%
 * 
 * @author Philip Milne
 * @author Scott Violet
 */

public class FileSystemModel extends AbstractTreeTableModel implements
		TreeTableModel {

	// Names of the columns.
	static protected String[] cNames = { "Name", "Size", "Type", "Modified" };

	// Types of the columns.
	static protected Class[] cTypes = { TreeTableModel.class, Integer.class,
			String.class, Date.class };

	// The the returned file length for directories.
	public static final Integer ZERO = new Integer(0);

	public FileSystemModel() {
		super(new FileNode(new File(File.separator)));
	}

	//
	// Some convenience methods.
	//

	protected File getFile(Object node) {
		FileNode fileNode = ((FileNode) node);
		return fileNode.getFile();
	}

	protected Object[] getChildren(Object node) {
		FileNode fileNode = ((FileNode) node);
		return fileNode.getChildren();
	}

	//
	// The TreeModel interface
	//

	public int getChildCount(Object node) {
		Object[] children = getChildren(node);
		return (children == null) ? 0 : children.length;
	}

	public Object getChild(Object node, int i) {
		return getChildren(node)[i];
	}

	// The superclass's implementation would work, but this is more efficient.
	public boolean isLeaf(Object node) {
		return getFile(node).isFile();
	}

	//
	// The TreeTableNode interface.
	//

	public int getColumnCount() {
		return cNames.length;
	}

	public String getColumnName(int column) {
		return cNames[column];
	}

	public Class getColumnClass(int column) {
		return cTypes[column];
	}

	public Object getValueAt(Object node, int column) {
		File file = getFile(node);
		try {
			switch (column) {
			case 0:
				return file.getName();
			case 1:
				return file.isFile() ? new Integer((int) file.length()) : ZERO;
			case 2:
				return file.isFile() ? "File" : "Directory";
			case 3:
				return new Date(file.lastModified());
			}
		} catch (SecurityException se) {
		}

		return null;
	}
}

/*
 * A FileNode is a derivative of the File class - though we delegate to the File
 * object rather than subclassing it. It is used to maintain a cache of a
 * directory's children and therefore avoid repeated access to the underlying
 * file system during rendering.
 */
class FileNode {
	File file;

	Object[] children;

	public FileNode(File file) {
		this.file = file;
	}

	// Used to sort the file names.
	static private MergeSort fileMS = new MergeSort() {
		public int compareElementsAt(int a, int b) {
			return ((String) toSort[a]).compareTo((String) toSort[b]);
		}
	};

	/**
	 * Returns the the string to be used to display this leaf in the JTree.
	 */
	public String toString() {
		return file.getName();
	}

	public File getFile() {
		return file;
	}

	/**
	 * Loads the children, caching the results in the children ivar.
	 */
	protected Object[] getChildren() {
		if (children != null) {
			return children;
		}
		try {
			String[] files = file.list();
			if (files != null) {
				fileMS.sort(files);
				children = new FileNode[files.length];
				String path = file.getPath();
				for (int i = 0; i < files.length; i++) {
					File childFile = new File(path, files[i]);
					children[i] = new FileNode(childFile);
				}
			}
		} catch (SecurityException se) {
		}
		return children;
	}
}