Use SWT to create browser application

本文提供了一个使用SWT创建浏览器应用的示例,包括窗口布局、资源加载、导航按钮实现及状态显示。

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error.CouldNotLoadResources = Unable to load resources
window.title = SWT Browser

Back				= Back
BrowserNotCreated	= Error - The Browser widget could not be instantiated. Please check the Browser widget is supported on this platform. Supported platforms and software requirements for the Browser widget are listed on the SWT FAQ web page.
Forward				= Forward
Stop				= Stop
Refresh				= Refresh
Go					= Go
Startup				= http://www.eclipse.org
package org.eclipse.swt.examples.browserexample;

import org.eclipse.swt.*;
import org.eclipse.swt.browser.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

import java.io.*;
import java.util.*;

public class BrowserExample {
	static ResourceBundle resourceBundle = ResourceBundle.getBundle("examples_browser");
	int index;
	boolean busy;
	Image images[];
	Image icon = null;
	boolean title = false;
	Composite parent;
	Text locationBar;
	Browser browser;
	ToolBar toolbar;
	Canvas canvas;
	ToolItem itemBack, itemForward;
	Label status;
	ProgressBar progressBar;
	SWTError error = null;

	static final String[] imageLocations = {
			"eclipse01.bmp", "eclipse02.bmp", "eclipse03.bmp", "eclipse04.bmp", "eclipse05.bmp",
			"eclipse06.bmp", "eclipse07.bmp", "eclipse08.bmp", "eclipse09.bmp", "eclipse10.bmp",
			"eclipse11.bmp", "eclipse12.bmp",};
	static final String iconLocation = "document.gif";
		
	public BrowserExample(Composite parent, boolean top) {
		this.parent = parent;
		try {
			browser = new Browser(parent, SWT.BORDER);
		} catch (SWTError e) {
			error = e;
			/* Browser widget could not be instantiated */
			parent.setLayout(new FillLayout());
			Label label = new Label(parent, SWT.CENTER | SWT.WRAP);
			label.setText(getResourceString("BrowserNotCreated"));
			parent.layout(true);
			return;
		}
		initResources();
		final Display display = parent.getDisplay();
		browser.setData("org.eclipse.swt.examples.browserexample.BrowserApplication", this);
		browser.addOpenWindowListener(new OpenWindowListener() {
			public void open(WindowEvent event) {
				Shell shell = new Shell(display);
				if (icon != null) shell.setImage(icon);
				shell.setLayout(new FillLayout());
				BrowserExample app = new BrowserExample(shell, false);
				app.setShellDecoration(icon, true);
				event.browser = app.getBrowser();
			}
		});
		if (top) {
			browser.setUrl(getResourceString("Startup"));
			show(false, null, null, true, true, true, true);
		} else {
			browser.addVisibilityWindowListener(new VisibilityWindowListener() {
				public void hide(WindowEvent e) {
				}
				public void show(WindowEvent e) {
					Browser browser = (Browser)e.widget;
					BrowserExample app = (BrowserExample)browser.getData("org.eclipse.swt.examples.browserexample.BrowserApplication");
					app.show(true, e.location, e.size, e.addressBar, e.menuBar, e.statusBar, e.toolBar);
				}
			});
			browser.addCloseWindowListener(new CloseWindowListener() {
				public void close(WindowEvent event) {
					Browser browser = (Browser)event.widget;
					Shell shell = browser.getShell();
					shell.close();
				}
			});
		}
	}

	/**
	 * Disposes of all resources associated with a particular
	 * instance of the BrowserApplication.
	 */	
	public void dispose() {
		freeResources();
	}
	
	/**
	 * Gets a string from the resource bundle.
	 * We don't want to crash because of a missing String.
	 * Returns the key if not found.
	 */
	static String getResourceString(String key) {
		try {
			return resourceBundle.getString(key);
		} catch (MissingResourceException e) {
			return key;
		} catch (NullPointerException e) {
			return "!" + key + "!";
		}			
	}
	
	public SWTError getError() { return error; }
	
	public Browser getBrowser() { return browser; }
	
	public void setShellDecoration(Image icon, boolean title) {
		this.icon = icon;
		this.title = title;
	}
	
	void show(boolean owned, Point location, Point size, boolean addressBar, boolean menuBar, boolean statusBar, boolean toolBar) {
		final Shell shell = browser.getShell();
		if (owned) {
			if (location != null) shell.setLocation(location);
			if (size != null) shell.setSize(shell.computeSize(size.x, size.y));
		}
		FormData data = null;
		if (toolBar) {
			toolbar = new ToolBar(parent, SWT.NONE);
			data = new FormData();
			data.top = new FormAttachment(0, 5);
			toolbar.setLayoutData(data);
			itemBack = new ToolItem(toolbar, SWT.PUSH);
			itemBack.setText(getResourceString("Back"));
			itemForward = new ToolItem(toolbar, SWT.PUSH);
			itemForward.setText(getResourceString("Forward"));
			final ToolItem itemStop = new ToolItem(toolbar, SWT.PUSH);
			itemStop.setText(getResourceString("Stop"));
			final ToolItem itemRefresh = new ToolItem(toolbar, SWT.PUSH);
			itemRefresh.setText(getResourceString("Refresh"));
			final ToolItem itemGo = new ToolItem(toolbar, SWT.PUSH);
			itemGo.setText(getResourceString("Go"));
			
			itemBack.setEnabled(browser.isBackEnabled());
			itemForward.setEnabled(browser.isForwardEnabled());
			Listener listener = new Listener() {
				public void handleEvent(Event event) {
					ToolItem item = (ToolItem)event.widget;
					if (item == itemBack) browser.back(); 
					else if (item == itemForward) browser.forward();
					else if (item == itemStop) browser.stop();
					else if (item == itemRefresh) browser.refresh();
					else if (item == itemGo) browser.setUrl(locationBar.getText());
				}
			};
			itemBack.addListener(SWT.Selection, listener);
			itemForward.addListener(SWT.Selection, listener);
			itemStop.addListener(SWT.Selection, listener);
			itemRefresh.addListener(SWT.Selection, listener);
			itemGo.addListener(SWT.Selection, listener);

			canvas = new Canvas(parent, SWT.NO_BACKGROUND);
			data = new FormData();
			data.width = 24;
			data.height = 24;
			data.top = new FormAttachment(0, 5);
			data.right = new FormAttachment(100, -5);
			canvas.setLayoutData(data);
			
			final Rectangle rect = images[0].getBounds();
			canvas.addListener(SWT.Paint, new Listener() {
				public void handleEvent(Event e) {
					Point pt = ((Canvas)e.widget).getSize();
					e.gc.drawImage(images[index], 0, 0, rect.width, rect.height, 0, 0, pt.x, pt.y);			
				}
			});
			canvas.addListener(SWT.MouseDown, new Listener() {
				public void handleEvent(Event e) {
					browser.setUrl(getResourceString("Startup"));
				}
			});
			
			final Display display = parent.getDisplay();
			display.asyncExec(new Runnable() {
				public void run() {
					if (canvas.isDisposed()) return;
					if (busy) {
						index++;
						if (index == images.length) index = 0;
						canvas.redraw();
					}
					display.timerExec(150, this);
				}
			});
		}
		if (addressBar) {
			locationBar = new Text(parent, SWT.BORDER);
			data = new FormData();
			if (toolbar != null) {
				data.top = new FormAttachment(toolbar, 0, SWT.TOP);
				data.left = new FormAttachment(toolbar, 5, SWT.RIGHT);
				data.right = new FormAttachment(canvas, -5, SWT.DEFAULT);			
			} else {
				data.top = new FormAttachment(0, 0);
				data.left = new FormAttachment(0, 0);
				data.right = new FormAttachment(100, 0);			
			}
			locationBar.setLayoutData(data);
			locationBar.addListener(SWT.DefaultSelection, new Listener() {
				public void handleEvent(Event e) {
					browser.setUrl(locationBar.getText());
				}
			});
		}
		if (statusBar) {
			status = new Label(parent, SWT.NONE);
			progressBar = new ProgressBar(parent, SWT.NONE);
			
			data = new FormData();
			data.left = new FormAttachment(0, 5);
			data.right = new FormAttachment(progressBar, 0, SWT.DEFAULT);
			data.bottom = new FormAttachment(100, -5);
			status.setLayoutData(data);
			
			data = new FormData();
			data.right = new FormAttachment(100, -5);
			data.bottom = new FormAttachment(100, -5);
			progressBar.setLayoutData(data);
			
			browser.addStatusTextListener(new StatusTextListener() {
				public void changed(StatusTextEvent event) {
					status.setText(event.text);	
				}
			});
		}
		parent.setLayout(new FormLayout());

		Control aboveBrowser = toolBar ? (Control)canvas : (addressBar ? (Control)locationBar : null);
		data = new FormData();
		data.left = new FormAttachment(0, 0);
		data.top = aboveBrowser != null ? new FormAttachment(aboveBrowser, 5, SWT.DEFAULT) : new FormAttachment(0, 0);
		data.right = new FormAttachment(100, 0);
		data.bottom = status != null ? new FormAttachment(status, -5, SWT.DEFAULT) : new FormAttachment(100, 0);
		browser.setLayoutData(data);
			
		if (statusBar || toolBar) {
			browser.addProgressListener(new ProgressListener() {
				public void changed(ProgressEvent event) {
					if (event.total == 0) return;                            
					int ratio = event.current * 100 / event.total;
					if (progressBar != null) progressBar.setSelection(ratio);
					busy = event.current != event.total;
					if (!busy) {
						index = 0;
						if (canvas != null) canvas.redraw();
					}
				}
				public void completed(ProgressEvent event) {
					if (progressBar != null) progressBar.setSelection(0);
					busy = false;
					index = 0;
					if (canvas != null) {
						itemBack.setEnabled(browser.isBackEnabled());
						itemForward.setEnabled(browser.isForwardEnabled());
						canvas.redraw();
					}
				}
			});
		}
		if (addressBar || statusBar || toolBar) {
			browser.addLocationListener(new LocationListener() {
				public void changed(LocationEvent event) {
					busy = true;
					if (event.top && locationBar != null) locationBar.setText(event.location);
				}
				public void changing(LocationEvent event) {
				}
			});
		}
		if (title) {
			browser.addTitleListener(new TitleListener() {
				public void changed(TitleEvent event) {
					shell.setText(event.title+" - "+getResourceString("window.title"));
				}
			});
		}
		parent.layout(true);
		if (owned) shell.open();
	}

	/**
	 * Grabs input focus
	 */
	public void focus() {
		if (locationBar != null) locationBar.setFocus();
		else if (browser != null) browser.setFocus();
		else parent.setFocus();
	}
	
	/**
	 * Frees the resources
	 */
	void freeResources() {
		if (images != null) {
			for (int i = 0; i < images.length; ++i) {
				final Image image = images[i];
				if (image != null) image.dispose();
			}
			images = null;
		}
	}
	
	/**
	 * Loads the resources
	 */
	void initResources() {
		final Class clazz = this.getClass();
		if (resourceBundle != null) {
			try {
				if (images == null) {
					images = new Image[imageLocations.length];
					for (int i = 0; i < imageLocations.length; ++i) {
						InputStream sourceStream = clazz.getResourceAsStream(imageLocations[i]);
						ImageData source = new ImageData(sourceStream);
						ImageData mask = source.getTransparencyMask();
						images[i] = new Image(null, source, mask);
						try {
							sourceStream.close();
						} catch (IOException e) {
							e.printStackTrace ();
						}
					}
				}
				return;
			} catch (Throwable t) {
			}
		}
		String error = (resourceBundle != null) ? getResourceString("error.CouldNotLoadResources") : "Unable to load resources";
		freeResources();
		throw new RuntimeException(error);
	}
	
	public static void main(String [] args) {
		Display display = new Display();
		Shell shell = new Shell(display);
		shell.setLayout(new FillLayout());
		shell.setText(getResourceString("window.title"));
		InputStream stream = BrowserExample.class.getResourceAsStream(iconLocation);
		Image icon = new Image(display, stream);
		shell.setImage(icon);
		try {
			stream.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		BrowserExample app = new BrowserExample(shell, true);
		app.setShellDecoration(icon, true);
		shell.open();
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch())
				display.sleep();
		}
		icon.dispose();
		app.dispose();
		display.dispose();
	}
}


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