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基于Eclipse 3.0的SWT编程

摘要: 基于Eclipse 3.0的SWT编程
<table cellSpacing=0 cellPadding=0 border=0 class="zh114" align="right"> <tr> <td > </td> </tr> </table>   一、SWT简介

  Java语言的声望和它在桌面应用程序(GUI程序)所取得的成就显然极不相符,至今仍然很少能看到非常成功Java桌面程序。虽然有JBuilder,Netbean,JProbe等大型软件作为代表,但这仍不能证明Java的GUI程序是成功的:它们的外观总是和同一操作系统平台下的其它软件显得格格不入。对机器配置的需求也似乎永无止境,这使得它们只能被一些总是拥有当前最高性能PC的程序员们所容忍,或是那些不在乎金钱和时间的专业用户所接受。对绝大多数计算机使用者来说,AWT或SWING代表着怪异的界面和无法接受的速度。Standard Widget Toolkit(SWT)或许是Java这一噩梦的终结者,广大Java程序员终于可以开发出高效率的GUI程序,它们拥有标准的外观,几乎没有人能看出你的程序是用Java写出来的,更为重要的是,这些程序是跨平台的。

  SWT本身仅仅是Eclipse组织为了开发Eclipse IDE环境所编写的一组底层图形界面 API。或许是无心插柳,或是有意为之,至今为止,SWT无论是在性能和外观上,都超越了SUN公司提供的AWT和SWING。目前Eclipse IDE已经开发到了2.1版本,SWT已经十分稳定。这里指的稳定应该包含两层意思:

  一是指性能上的稳定,其中的关键是源于SWT的设计理念。SWT最大化了操作系统的图形构件API,就是说只要操作系统提供了相应图形的构件,那么SWT只是简单应用JNI技术调用它们,只有那些操作系统中不提供的构件,SWT才自己去做一个模拟的实现。可以看出SWT的性能上的稳定大多时候取决于相应操作系统图形构件的稳定性。

  另一个稳定是指SWT API包中的类、方法的名称和结构已经少有改变,程序员不用担心由于Eclipse组织开发进度很快(Eclipse IDE每天都会有一个Nightly版本的发布),而导致自己的程序代码变化过大。从一个版本的SWT更新至另一版本,通常只需要简单将SWT包换掉就可以了。

  二、Eclipse3.0的SWT编程

  1.SWT比AWT和Swing要快多,因为它是利用操作系统的界面组件生成UI的,在java桌面设计领域掀起一场革命

  2.环境配置:

  windows系统+eclipse3.0

  3.具体操作:

  (1).新建一java项目,命名SWT,文件结构如下:

  +swt
  +bin(编译输出)
  +src(原文件)
  +AddressBookUI.java
  +swt-awt-win32-3062.dll(以下均从eclipse\plugins\org.eclipse.swt.win32_3.0.1\os\win32\x86下导入)
  +swt-win32-3062.dll
  +javaw.exe.manifest

  (2).到项目的properties里,在java build path | libraries里将swt.jar导入

  (3).AddressBookUI.java原代码如下:

<table borderColor=#ffcc66 width="90%" align=center bgColor=#e3e3e3 border=1> <tr> <td>import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Group;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
public class AddressBookUI {
 private Shell shell;
 private Text miscText;
 private Text addrText;
 private Text emailText;
 private Text phoneText;
 private Text lnameText;
 private Text fnameText;
 private Button cancelButton;
 private Button saveButton;
 private Button nextButton;
 private Button prevButton;
 private Button editButton;
 private Button deleteButton;
 private Button newButton;
 public static void main(String[] args) {
  AddressBookUI window = new AddressBookUI();
  window.open();
 }
 public void open() {
  final Display display = new Display();
  shell = new Shell();
  shell.setSize(610, 477);
  shell.setText("Address Book");
 {
  newButton = new Button(shell, SWT.NONE);
  newButton.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    clearText();
    setTextEditable(true);
    enableEditButtons(false);
    enableSaveButtons(true);

    System.out.println("New button selected.");
   }
  });
  newButton.setBounds(10, 380, 75, 35);
  newButton.setText("New");
 }
 {
  deleteButton = new Button(shell, SWT.NONE);
  deleteButton.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    clearText();

    System.out.println("Delete button selected.");
   }
  });
  deleteButton.setBounds(85, 380, 75, 35);
  deleteButton.setText("Delete");
 }
 {
  editButton = new Button(shell, SWT.NONE);
  editButton.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    setTextEditable(true);
    enableEditButtons(false);
    enableSaveButtons(true);
  
    System.out.println("Edit button selected.");
   }
  });
  editButton.setBounds(160, 380, 75, 35);
  editButton.setText("Edit");
 }
 {
  prevButton = new Button(shell, SWT.NONE);
  prevButton.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    System.out.println("Previous button selected.");
   }
  });
  prevButton.setBounds(265, 380, 75, 35);
  prevButton.setText("Previous");
 }
 {
  nextButton = new Button(shell, SWT.NONE);
  nextButton.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    System.out.println("Next button selected.");
   }
  });
  nextButton.setBounds(340, 380, 75, 35);
  nextButton.setText("Next");
 }
 {
  saveButton = new Button(shell, SWT.NONE);
  saveButton.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    setTextEditable(false);
    enableEditButtons(true);
    enableSaveButtons(false);
 
    System.out.println("Save button selected.");
   }
  });
  saveButton.setBounds(445, 380, 75, 35);
  saveButton.setText("Save");
  saveButton.setEnabled(false);
 }
 {
  cancelButton = new Button(shell, SWT.NONE);
  cancelButton.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    setTextEditable(false);
    enableEditButtons(true);
    enableSaveButtons(false);

    System.out.println("Cancel button selected.");
   }
  });
  cancelButton.setBounds(520, 380, 75, 35);
  cancelButton.setText("Cancel");
  cancelButton.setEnabled(false);
 }
 {
  final Group group = new Group(shell, SWT.NONE);
  group.setText("Details");
  group.setBounds(10, 10, 585, 355);
  {
   final Label label = new Label(group, SWT.NONE);
   label.setBounds(10, 20, 135, 25);
   label.setText("First Name:");
  }
  {
   final Label label = new Label(group, SWT.NONE);
   label.setBounds(10, 60, 135, 25);
   label.setText("Last Name:");
  }
  {
   final Label label = new Label(group, SWT.NONE);
   label.setBounds(10, 100, 135, 25);
   label.setText("Phone:");
  }
  {
   final Label label = new Label(group, SWT.NONE);
   label.setBounds(10, 140, 135, 25);
   label.setText("Email:");
  }
  {
   final Label label = new Label(group, SWT.NONE);
   label.setBounds(10, 180, 135, 25);
   label.setText("Address:");
  }
  {
   final Label label = new Label(group, SWT.NONE);
   label.setBounds(10, 255, 135, 25);
   label.setText("Miscellaneous Information:");
  }
  {
   fnameText = new Text(group, SWT.BORDER | SWT.READ_ONLY);
   fnameText.setBounds(150, 15, 420, 25);
  }
  {
   lnameText = new Text(group, SWT.BORDER | SWT.READ_ONLY);
   lnameText.setBounds(150, 55, 420, 25);
  }
  {
   phoneText = new Text(group, SWT.BORDER | SWT.READ_ONLY);
   phoneText.setBounds(150, 95, 420, 25);
  }
  {
   emailText = new Text(group, SWT.BORDER | SWT.READ_ONLY);
   emailText.setBounds(150, 135, 420, 25);
  }
  {
   addrText = new Text(group, SWT.BORDER | SWT.READ_ONLY | SWT.V_SCROLL);
   addrText.setBounds(150, 175, 420, 60);
  }
  {
   miscText = new Text(group, SWT.BORDER | SWT.READ_ONLY | SWT.V_SCROLL);
   miscText.setBounds(150, 250, 420, 65);
  }
 }

 setupMenu();

 shell.open();
 while (!shell.isDisposed()) {
  if (!display.readAndDispatch())
   display.sleep();
 }
}

private void setupMenu() {
 //create the menu bar
 Menu menu = new Menu(shell, SWT.BAR);
 shell.setMenuBar(menu);
 //add the File option to it
 MenuItem file = new MenuItem(menu, SWT.CASCADE);
 file.setText("File");
 //create a menu for the File option
 file.setMenu(new Menu(file));
 //add MenuItems to the File menu
 MenuItem prevItem = new MenuItem(new Menu(file), SWT.NONE);
 prevItem.setText("Previous");

 MenuItem nextItem = new MenuItem(new Menu(file), SWT.PUSH);
 nextItem.setText("Next");

 MenuItem seperator = new MenuItem(new Menu(file), SWT.SEPARATOR);
 MenuItem quitItem = new MenuItem(new Menu(file), SWT.PUSH);
 quitItem.setText("Quit");
 //add listeners for the actions
 prevItem.addListener(SWT.Selection, new Listener() {
  public void handleEvent(Event e) {
   System.out.println("Previous menu item selected.");
  }
 });
 nextItem.addListener(SWT.Selection, new Listener() {
  public void handleEvent(Event e) {
   System.out.println("Next menu item selected.");
  }
 });
 quitItem.addListener(SWT.Selection, new Listener() {
  public void handleEvent(Event e) {
   shell.dispose();
  }
 });
}

private void clearText() {
 fnameText.setText("");
 lnameText.setText("");
 phoneText.setText("");
 emailText.setText("");
 addrText.setText("");
 miscText.setText("");
}

private void setTextEditable(boolean editable) {
 fnameText.setEditable(editable);
 lnameText.setEditable(editable);
 phoneText.setEditable(editable);
 emailText.setEditable(editable);
 addrText.setEditable(editable);
 miscText.setEditable(editable);
}

private void enableEditButtons(boolean enable) {
 newButton.setEnabled(enable);
 deleteButton.setEnabled(enable);
 editButton.setEnabled(enable);
}

private void enableSaveButtons(boolean enable) {
 saveButton.setEnabled(enable);
 cancelButton.setEnabled(enable);
}
}</td></tr></table>
  (4).测试运行,run就可以啦

<table width="96%"> <tr> <td background="http:///images/dian.gif" height="3"></td> </tr> </table>

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