任何人都可以在下面的Treeviewer代码中解释控制流程如何？

Question

该程序运行正常，但我无法看到它们是如何连接在一起的。我的意思是，我不会调用由Icontent提供程序或Ilabel Provider扩展的类中的方法;怎么叫它？

我从http://java2s.com/复制了代码。

package com.test;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.jface.viewers.ILabelProvider;
import org.eclipse.jface.viewers.ILabelProviderListener;
import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.LabelProviderChangedEvent;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.window.ApplicationWindow;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;


/**
 * This class demonstrates TreeViewer. It shows the drives, directories, and
 * files on the system.
 */
public class FileTree extends ApplicationWindow {
  /**
   * FileTree constructor
   */
  public FileTree() {
    super(null);
  }

  /**
   * Runs the application
   */
  public void run() {
    // Don't return from open() until window closes
    setBlockOnOpen(true);

    // Open the main window
    open();

    // Dispose the display
    Display.getCurrent().dispose();
  }

  /**
   * Configures the shell
   * 
   * @param shell
   *            the shell
   */
  protected void configureShell(Shell shell) {
    super.configureShell(shell);

    // Set the title bar text and the size
    shell.setText("File Tree");
    shell.setSize(400, 400);
  }

  /**
   * Creates the main window's contents
   * 
   * @param parent
   *            the main window
   * @return Control
   */
  protected Control createContents(Composite parent) {
    Composite composite = new Composite(parent, SWT.NONE);
    composite.setLayout(new GridLayout(1, false));

    // Add a checkbox to toggle whether the labels preserve case
    Button preserveCase = new Button(composite, SWT.CHECK);
    preserveCase.setText("&Preserve case");

    // Create the tree viewer to display the file tree
    final TreeViewer tv = new TreeViewer(composite);
    tv.getTree().setLayoutData(new GridData(GridData.FILL_BOTH));
    tv.setContentProvider(new FileTreeContentProvider());
    tv.setLabelProvider(new FileTreeLabelProvider());
    tv.setInput("root"); // pass a non-null that will be ignored

    // When user checks the checkbox, toggle the preserve case attribute
    // of the label provider
    preserveCase.addSelectionListener(new SelectionAdapter() {
      public void widgetSelected(SelectionEvent event) {
        boolean preserveCase = ((Button) event.widget).getSelection();
        FileTreeLabelProvider ftlp = (FileTreeLabelProvider) tv
            .getLabelProvider();
        ftlp.setPreserveCase(preserveCase);
      }
    });
    return composite;
  }

  /**
   * The application entry point
   * 
   * @param args
   *            the command line arguments
   */
  public static void main(String[] args) {
    new FileTree().run();
  }
}

/**
 * This class provides the content for the tree in FileTree
 */

class FileTreeContentProvider implements ITreeContentProvider {
  /**
   * Gets the children of the specified object
   * 
   * @param arg0
   *            the parent object
   * @return Object[]
   */
  public Object[] getChildren(Object arg0) {
    // Return the files and subdirectories in this directory
    return ((File) arg0).listFiles();
  }

  /**
   * Gets the parent of the specified object
   * 
   * @param arg0
   *            the object
   * @return Object
   */
  public Object getParent(Object arg0) {
    // Return this file's parent file
    return ((File) arg0).getParentFile();
  }

  /**
   * Returns whether the passed object has children
   * 
   * @param arg0
   *            the parent object
   * @return boolean
   */
  public boolean hasChildren(Object arg0) {
    // Get the children
    Object[] obj = getChildren(arg0);

    // Return whether the parent has children
    return obj == null ? false : obj.length > 0;
  }

  /**
   * Gets the root element(s) of the tree
   * 
   * @param arg0
   *            the input data
   * @return Object[]
   */
  public Object[] getElements(Object arg0) {
    // These are the root elements of the tree
    // We don't care what arg0 is, because we just want all
    // the root nodes in the file system
    return File.listRoots();
  }

  /**
   * Disposes any created resources
   */
  public void dispose() {
    // Nothing to dispose
  }

  /**
   * Called when the input changes
   * 
   * @param arg0
   *            the viewer
   * @param arg1
   *            the old input
   * @param arg2
   *            the new input
   */
  public void inputChanged(Viewer arg0, Object arg1, Object arg2) {
    // Nothing to change
  }
}

/**
 * This class provides the labels for the file tree
 */

class FileTreeLabelProvider implements ILabelProvider {
  // The listeners
  private List listeners;

  // Images for tree nodes
  private Image file;

  private Image dir;

  // Label provider state: preserve case of file names/directories
  boolean preserveCase;

  /**
   * Constructs a FileTreeLabelProvider
   */
  public FileTreeLabelProvider() {
    // Create the list to hold the listeners
    listeners = new ArrayList();

    // Create the images
    try {
      file = new Image(null, new FileInputStream("images/file.gif"));
      dir = new Image(null, new FileInputStream("images/directory.gif"));
    } catch (FileNotFoundException e) {
      // Swallow it; we'll do without images
    }
  }

  /**
   * Sets the preserve case attribute
   * 
   * @param preserveCase
   *            the preserve case attribute
   */
  public void setPreserveCase(boolean preserveCase) {
    this.preserveCase = preserveCase;

    // Since this attribute affects how the labels are computed,
    // notify all the listeners of the change.
    LabelProviderChangedEvent event = new LabelProviderChangedEvent(this);
    for (int i = 0, n = listeners.size(); i < n; i++) {
      ILabelProviderListener ilpl = (ILabelProviderListener) listeners
          .get(i);
      ilpl.labelProviderChanged(event);
    }
  }

  /**
   * Gets the image to display for a node in the tree
   * 
   * @param arg0
   *            the node
   * @return Image
   */
  public Image getImage(Object arg0) {
    // If the node represents a directory, return the directory image.
    // Otherwise, return the file image.
    return ((File) arg0).isDirectory() ? dir : file;
  }

  /**
   * Gets the text to display for a node in the tree
   * 
   * @param arg0
   *            the node
   * @return String
   */
  public String getText(Object arg0) {
    // Get the name of the file
    String text = ((File) arg0).getName();

    // If name is blank, get the path
    if (text.length() == 0) {
      text = ((File) arg0).getPath();
    }

    // Check the case settings before returning the text
    return preserveCase ? text : text.toUpperCase();
  }

  /**
   * Adds a listener to this label provider
   * 
   * @param arg0
   *            the listener
   */
  public void addListener(ILabelProviderListener arg0) {
    listeners.add(arg0);
  }

  /**
   * Called when this LabelProvider is being disposed
   */
  public void dispose() {
    // Dispose the images
    if (dir != null)
      dir.dispose();
    if (file != null)
      file.dispose();
  }

  /**
   * Returns whether changes to the specified property on the specified
   * element would affect the label for the element
   * 
   * @param arg0
   *            the element
   * @param arg1
   *            the property
   * @return boolean
   */
  public boolean isLabelProperty(Object arg0, String arg1) {
    return false;
  }

  /**
   * Removes the listener
   * 
   * @param arg0
   *            the listener to remove
   */
  public void removeListener(ILabelProviderListener arg0) {
    listeners.remove(arg0);
  }
}

Answer 1

这些行......

tv.setContentProvider(new FileTreeContentProvider());
tv.setLabelProvider(new FileTreeLabelProvider());

...正在TreeViewer组件上设置代码中的类。

TreeViewer将调用您提供的方法来创建树内容和标签。

如果要查看确切的流，则应在其中一个方法上设置断点并在调试器下运行。然后，当调用方法时，您将能够看到调用堆栈。