Bonjour je cheche a afficher une vue de mon systéme de fichier dans un JTree,
j'ai trouvée ce code qui fonctionne : http://www.pushing-pixels.org/wp-con...etreepanel.txt


seulement je ne comprend pas du tout comment il fonctionne si quelqu’un peut m'aider ce serait vraiment cool merci

Code : Sélectionner tout - Visualiser dans une fenêtre à part
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import java.awt.BorderLayout;
import java.awt.Component;
import java.io.File;
import java.util.*;
 
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import javax.swing.filechooser.FileSystemView;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreeNode;
 
/**
 * @author Kirill Grouchnikov
 */
public class FileTreePanel extends JPanel {
	/**
         * File system view.
         */
	protected static FileSystemView fsv = FileSystemView.getFileSystemView();
 
	/**
         * Renderer for the file tree.
         * 
         * @author Kirill Grouchnikov
         */
	private static class FileTreeCellRenderer extends DefaultTreeCellRenderer {
		/**
                 * Icon cache to speed the rendering.
                 */
		private Map<String, Icon> iconCache = new HashMap<String, Icon>();
 
		/**
                 * Root name cache to speed the rendering.
                 */
		private Map<File, String> rootNameCache = new HashMap<File, String>();
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.DefaultTreeCellRenderer#getTreeCellRendererComponent(javax.swing.JTree,
		 *      java.lang.Object, boolean, boolean, boolean, int, boolean)
		 */
		@Override
		public Component getTreeCellRendererComponent(JTree tree, Object value,
				boolean sel, boolean expanded, boolean leaf, int row,
				boolean hasFocus) {
			FileTreeNode ftn = (FileTreeNode) value;
			File file = ftn.file;
			String filename = "";
			if (file != null) {
				if (ftn.isFileSystemRoot) {
					// long start = System.currentTimeMillis();
					filename = this.rootNameCache.get(file);
					if (filename == null) {
						filename = fsv.getSystemDisplayName(file);
						this.rootNameCache.put(file, filename);
					}
					// long end = System.currentTimeMillis();
					// System.out.println(filename + ":" + (end - start));
				} else {
					filename = file.getName();
				}
			}
			JLabel result = (JLabel) super.getTreeCellRendererComponent(tree,
					filename, sel, expanded, leaf, row, hasFocus);
			if (file != null) {
				Icon icon = this.iconCache.get(filename);
				if (icon == null) {
					// System.out.println("Getting icon of " + filename);
					icon = fsv.getSystemIcon(file);
					this.iconCache.put(filename, icon);
				}
				result.setIcon(icon);
			}
			return result;
		}
	}
 
	/**
         * A node in the file tree.
         * 
         * @author Kirill Grouchnikov
         */
	private static class FileTreeNode implements TreeNode {
		/**
                 * Node file.
                 */
		private File file;
 
		/**
                 * Children of the node file.
                 */
		private File[] children;
 
		/**
                 * Parent node.
                 */
		private TreeNode parent;
 
		/**
                 * Indication whether this node corresponds to a file system root.
                 */
		private boolean isFileSystemRoot;
 
		/**
                 * Creates a new file tree node.
                 * 
                 * @param file
                 *            Node file
                 * @param isFileSystemRoot
                 *            Indicates whether the file is a file system root.
                 * @param parent
                 *            Parent node.
                 */
		public FileTreeNode(File file, boolean isFileSystemRoot, TreeNode parent) {
			this.file = file;
			this.isFileSystemRoot = isFileSystemRoot;
			this.parent = parent;
			this.children = this.file.listFiles();
			if (this.children == null)
				this.children = new File[0];
		}
 
		/**
                 * Creates a new file tree node.
                 * 
                 * @param children
                 *            Children files.
                 */
		public FileTreeNode(File[] children) {
			this.file = null;
			this.parent = null;
			this.children = children;
		}
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.TreeNode#children()
		 */
		public Enumeration<?> children() {
			final int elementCount = this.children.length;
			return new Enumeration<File>() {
				int count = 0;
 
				/*
				 * (non-Javadoc)
				 * 
				 * @see java.util.Enumeration#hasMoreElements()
				 */
				public boolean hasMoreElements() {
					return this.count < elementCount;
				}
 
				/*
				 * (non-Javadoc)
				 * 
				 * @see java.util.Enumeration#nextElement()
				 */
				public File nextElement() {
					if (this.count < elementCount) {
						return FileTreeNode.this.children[this.count++];
					}
					throw new NoSuchElementException("Vector Enumeration");
				}
			};
 
		}
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.TreeNode#getAllowsChildren()
		 */
		public boolean getAllowsChildren() {
			return true;
		}
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.TreeNode#getChildAt(int)
		 */
		public TreeNode getChildAt(int childIndex) {
			return new FileTreeNode(this.children[childIndex],
					this.parent == null, this);
		}
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.TreeNode#getChildCount()
		 */
		public int getChildCount() {
			return this.children.length;
		}
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.TreeNode#getIndex(javax.swing.tree.TreeNode)
		 */
		public int getIndex(TreeNode node) {
			FileTreeNode ftn = (FileTreeNode) node;
			for (int i = 0; i < this.children.length; i++) {
				if (ftn.file.equals(this.children[i]))
					return i;
			}
			return -1;
		}
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.TreeNode#getParent()
		 */
		public TreeNode getParent() {
			return this.parent;
		}
 
		/*
		 * (non-Javadoc)
		 * 
		 * @see javax.swing.tree.TreeNode#isLeaf()
		 */
		public boolean isLeaf() {
			return (this.getChildCount() == 0);
		}
	}
 
	/**
         * The file tree.
         */
	private JTree tree;
 
	/**
         * Creates the file tree panel.
         */
	public FileTreePanel() {
		this.setLayout(new BorderLayout());
 
		File[] roots = File.listRoots();
		FileTreeNode rootTreeNode = new FileTreeNode(roots);
		this.tree = new JTree(rootTreeNode);
		this.tree.setCellRenderer(new FileTreeCellRenderer());
		this.tree.setRootVisible(false);
		final JScrollPane jsp = new JScrollPane(this.tree);
		jsp.setBorder(new EmptyBorder(0, 0, 0, 0));
		this.add(jsp, BorderLayout.CENTER);
	}
 
	public static void main(String[] args) {
		SwingUtilities.invokeLater(new Runnable() {
			public void run() {
				JFrame frame = new JFrame("File tree");
				frame.setSize(500, 400);
				frame.setLocationRelativeTo(null);
				frame.add(new FileTreePanel());
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
			}
		});
	}
}