Eclipse开发经典教程：展现组件

/**
* 为了节省篇幅，所有的import类已经被注释
* 读者可以通过ctrl+shift+o快捷键，自动引入所依赖的类
* 如果有问题可发邮件到ganshm@gmail.com
* */
publicclass MenuExample {
Display display;
Shell shell;
Menu menuBar, fileMenu, editMenu;
MenuItem fileMenuHeader, editMenuHeader;
MenuItem fileExitItem, fileSaveItem, fileEnglishItem, fileGermanItem,
editCopyItem;
Text text;
public MenuExample() {
display =new Display();
shell =new Shell(display);
shell.setText("Menu Example");
shell.setSize(300, 200);
text =new Text(shell, SWT.BORDER);
text.setBounds(80, 50, 150, 25);
//添加主菜单项 
menuBar =new Menu(shell, SWT.BAR);
//添加一级子菜单 
fileMenuHeader =new MenuItem(menuBar, SWT.CASCADE);
fileMenuHeader.setText("&File");
//添加一级子菜单的菜单项 
fileMenu =new Menu(shell, SWT.DROP_DOWN);
fileMenuHeader.setMenu(fileMenu);
fileSaveItem =new MenuItem(fileMenu, SWT.PUSH);
fileSaveItem.setText("&Save");
fileEnglishItem =new MenuItem(fileMenu, SWT.RADIO);
fileEnglishItem.setText("English");
fileGermanItem =new MenuItem(fileMenu, SWT.RADIO);
fileGermanItem.setText("German");
fileExitItem =new MenuItem(fileMenu, SWT.PUSH);
fileExitItem.setText("E&xit");
editMenuHeader =new MenuItem(menuBar, SWT.CASCADE);
editMenuHeader.setText("&Edit");
editMenu =new Menu(shell, SWT.DROP_DOWN);
editMenuHeader.setMenu(editMenu);
editCopyItem =new MenuItem(editMenu, SWT.PUSH);
editCopyItem.setText("&Copy");
//添加菜单项的事件监听器 
fileExitItem.addSelectionListener(new MenuItemListener());
fileSaveItem.addSelectionListener(new MenuItemListener());
editCopyItem.addSelectionListener(new MenuItemListener());
fileEnglishItem.addSelectionListener(new RadioItemListener());
fileGermanItem.addSelectionListener(new RadioItemListener());
shell.setMenuBar(menuBar);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
class MenuItemListener extends SelectionAdapter {
publicvoid widgetSelected(SelectionEvent event) {
text.setText("You selected "+ ((MenuItem) event.widget).getText());
if (((MenuItem) event.widget).getText().equals("E&xit")) {
shell.close();
}
}
}
class RadioItemListener extends SelectionAdapter {
publicvoid widgetSelected(SelectionEvent event) {
MenuItem item = (MenuItem) event.widget;
text.setText(item.getText() +" is on.");
}
}
publicstaticvoid main(String[] args) {
MenuExample menuExample =new MenuExample();
}
} 

publicclass ToolBarExample {
Display display =new Display();
Shell shell =new Shell(display);
ToolBar toolBar;
public ToolBarExample() {
//添加工具栏 
toolBar =new ToolBar(shell, SWT.FLAT | SWT.WRAP | SWT.RIGHT);
//添加工具项 
ToolItem itemPush =new ToolItem(toolBar, SWT.PUSH);
itemPush.setText("PUSH item");
//设置工具项的显示图标
//Image icon = new Image(shell.getDisplay(), "icons/new.gif");
//itemPush.setImage(icon); 
ToolItem itemCheck =new ToolItem(toolBar, SWT.CHECK);
itemCheck.setText("CHECK item");
ToolItem itemRadio1 =new ToolItem(toolBar, SWT.RADIO);
itemRadio1.setText("RADIO item 1");
ToolItem itemRadio2 =new ToolItem(toolBar, SWT.RADIO);
itemRadio2.setText("RADIO item 2");
ToolItem itemSeparator =new ToolItem(toolBar, SWT.SEPARATOR);
final ToolItem itemDropDown =new ToolItem(toolBar, SWT.DROP_DOWN);
itemDropDown.setText("DROP_DOWN item");
itemDropDown.setToolTipText("Click here to see a drop down menu ...");
final Menu menu =new Menu(shell, SWT.POP_UP);
new MenuItem(menu, SWT.PUSH).setText("Menu item 1");
new MenuItem(menu, SWT.PUSH).setText("Menu item 2");
new MenuItem(menu, SWT.SEPARATOR);
new MenuItem(menu, SWT.PUSH).setText("Menu item 3");
//设置工具项的事件监听器 
itemDropDown.addListener(SWT.Selection, new Listener() {
publicvoid handleEvent(Event event) {
if (event.detail == SWT.ARROW) {
Rectangle bounds = itemDropDown.getBounds();
Point point = toolBar.toDisplay(bounds.x, bounds.y
+ bounds.height);
//设置菜单的显示位置 
menu.setLocation(point);
menu.setVisible(true);
}
}
});
//设置工具项的事件监听器 
Listener selectionListener =new Listener() {
publicvoid handleEvent(Event event) {
ToolItem item = (ToolItem) event.widget;
System.out.println(item.getText() +" is selected");
if ((item.getStyle() & SWT.RADIO) !=0
|| (item.getStyle() & SWT.CHECK) !=0)
System.out.println("Selection status: "
+ item.getSelection());
}
};
itemPush.addListener(SWT.Selection, selectionListener);
itemCheck.addListener(SWT.Selection, selectionListener);
itemRadio1.addListener(SWT.Selection, selectionListener);
itemRadio2.addListener(SWT.Selection, selectionListener);
itemDropDown.addListener(SWT.Selection, selectionListener);
toolBar.pack();
shell.addListener(SWT.Resize, new Listener() {
publicvoid handleEvent(Event event) {
Rectangle clientArea = shell.getClientArea();
toolBar.setSize(toolBar.computeSize(clientArea.width,
SWT.DEFAULT));
}
});
shell.setSize(400, 100);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
publicstaticvoid main(String[] args) {
new ToolBarExample();
}
} 

publicclass CoolBarExample extends ApplicationWindow {
public CoolBarExample() {
super(null);
}
protected Control createContents(Composite parent) {
getShell().setText("CoolBar Test");
String asCoolItemSection[] = { "File", "Formatting", "Search" };
//添加CoolBar 
CoolBar composite =new CoolBar(parent, SWT.NONE);
for (int idxCoolItem =0; idxCoolItem <3; ++idxCoolItem) {
CoolItem item =new CoolItem(composite, SWT.NONE);
//添加子组件 
ToolBar tb =new ToolBar(composite, SWT.FLAT);
for (int idxItem =0; idxItem <3; ++idxItem) {
ToolItem ti =new ToolItem(tb, SWT.NONE);
ti
.setText(asCoolItemSection[idxCoolItem] +" Item #"
+ idxItem);
}
Point p = tb.computeSize(SWT.DEFAULT, SWT.DEFAULT);
tb.setSize(p);
Point p2 = item.computeSize(p.x, p.y);
//设置为一个CoolItem的控制类 
item.setControl(tb);
item.setSize(p2);
}
return composite;
}
publicstaticvoid main(String[] args) {
CoolBarExample app =new CoolBarExample();
app.setBlockOnOpen(true);
app.open();
Display.getCurrent().dispose();
}
} 

publicclass SliderExample {
Display dispaly;
Shell shell;
SliderExample() {
dispaly =new Display();
shell =new Shell(dispaly);
shell.setSize(300, 250);
shell.setText("A Slider Example");
//添加Slider对象 
final Slider slide =new Slider(shell, SWT.V_SCROLL);
//设置Slider的位置和大小 
slide.setBounds(170, 25, 25, 20);
//设置Slider的最小值 
slide.setMinimum(0);
//设置Slider的最大值 
slide.setMaximum(100);
//设置Slider单击左右箭头的增加或递减值 
slide.setIncrement(1);
final Text t =new Text(shell, SWT.BORDER);
t.setBounds(115, 25, 55, 20);
t.setText("0");
t.setFocus();
//添加Slider的事件监听器 
slide.addSelectionListener(new SelectionAdapter() {
publicvoid widgetSelected(SelectionEvent e) {
t.setText(new Integer(slide.getSelection()).toString());
}
});
shell.open();
while (!shell.isDisposed()) {
if (!dispaly.readAndDispatch())
dispaly.sleep();
}
dispaly.dispose();
}
publicstaticvoid main(String[] args) {
new SliderExample();
}
} 

publicclass ScaleExample {
Display display =new Display();
Shell shell =new Shell(display);
Scale scale;
Text value;
public ScaleExample() {
shell.setLayout(new GridLayout(1, true));
Label label =new Label(shell, SWT.NULL);
label.setText("Volume:");
//添加Scale组件 
scale =new Scale(shell, SWT.VERTICAL);
scale.setBounds(0, 0, 40, 200);
//设置Scale的最大值 
scale.setMaximum(20);
//设置Scale的最小值 
scale.setMinimum(0);
//设置Scale的增量值 
scale.setPageIncrement(5);
//添加Scale的事件监听器 
scale.addListener(SWT.Selection, new Listener() {
publicvoid handleEvent(Event event) {
int perspectiveValue = scale.getMaximum() - scale.getSelection() +
scale.getMinimum();
value.setText("Vol: "+ perspectiveValue);
}
});
value =new Text(shell, SWT.BORDER | SWT.SINGLE);
value.setEditable(false);
scale.setLayoutData(new GridData(GridData.HORIZONTAL_ALIGN_CENTER));
value.setLayoutData(new GridData(GridData.HORIZONTAL_ALIGN_CENTER));
shell.pack();
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
privatevoid init() {
}
publicstaticvoid main(String[] args) {
new ScaleExample();
}
} 

上例中，通过事件监听器监听当前选择的刻度，并用Text组件显示出来，程序运行效果如图5所示。

图5 Scale组件

Scale组件能够精确的显示刻度，用户可以设制好刻度的范围，这是非常有用的。

进度条组件ProgressBar ProgressBar是SWT中的进度条组件。进度条提供了比较长时间操作的进度信息。添加ProgressBar组件的步骤如下： 1. 创建ProgressBar对象，并指定创建的样式，例如“ProgressBar pb1 = new ProgressBar (shell, SWT.HORIZONTAL | SWT.SMOOTH);”。 2. 设置ProgressBar的最大值和最小值，例如“pb1.setMaximum(30);”。 3. 在长时间的任务中设置当前进度条的进度，例如“progressBar.setSelection (progressBar.getSelection() + 1);”。 进度条能反映当前的工作进度，为了配合处理长时间的任务，进度条经常配合线程使用，以免产生阻塞影响界面的操作。为了更好地掌握ProgressBar组件，下面通过一个实例演示如何创建ProgressBar组件，代码如例程6所示。例程6 ProgressBarExample.java

publicclass ProgressBarExample {
publicstaticvoid main(String[] args) {
Display display =new Display();
Shell shell =new Shell(display);
shell.setLayout(new GridLayout());
//添加平滑的进度条 
ProgressBar pb1 =new ProgressBar(shell, SWT.HORIZONTAL | SWT.SMOOTH);
pb1.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
//设置进度条的最小值 
pb1.setMinimum(0);
//设置进度条的最大值 
pb1.setMaximum(30);
//添加自动递增的进度条 
ProgressBar pb2 =new ProgressBar(shell, SWT.HORIZONTAL |
SWT.INDETERMINATE);
pb2.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
//添加线程，在线程中处理长时间的任务，并最终反映在平滑进度条上 
new LongRunningOperation(display, pb1).start();
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
}
}
class LongRunningOperation extends Thread {
private Display display;
private ProgressBar progressBar;
public LongRunningOperation(Display display, ProgressBar progressBar) {
this.display = display;
this.progressBar = progressBar;
}
publicvoid run() {
//模仿长时间的任务 
for (int i =0; i <30; i++) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
display.asyncExec(new Runnable() {
publicvoid run() {
if (progressBar.isDisposed()) return;
//进度条递增 
progressBar.setSelection(progressBar.getSelection() +1);
}
});
}
}
} 

以上代码添加了两个进度条，一个进度条为自动显示增加进度的信息（SWT.INDETERMINAT样式），另外一个进度条通过线程处理长时间的任务，并设定进度条的信息。程序运行效果如图6所示。

图6 ProgressBar组件

进度条有不同的样式，在程序中，开发人员可以控制进度条的进度，执行某些长时间的操作。