其它常用的GUI构件设计

1、其它常用的GUI构件设计1：JtextArea:：用于多行文本的操作类层次结构：javax.swing Class JTextArea | +- | +- | +- | +- | +-主要构造函数：Constructor SummaryJTextArea()           Constructs a new TextArea.JTextArea(Document doc)          &

2、#160;Constructs a new JTextArea with the given document model, and defaults for all of the other arguments (null, 0, 0).JTextArea(Document doc, String text, int rows, int columns)           Constructs a new JTextArea with the spec

3、ified number of rows and columns, and the given model.JTextArea(int rows, int columns)           Constructs a new empty TextArea with the specified number of rows and columns.JTextArea(String text)       &

4、#160;   Constructs a new TextArea with the specified text displayed.JTextArea(String text, int rows, int columns)           Constructs a new TextArea with the specified text and number of rows and columns.常用方法成员分析：1：得到(g

5、et)或设置（set）区域内的文本信息。这些成员方法是从其父类继承而来。包括全部或部分（通过selected）。2：得到(get)或设置（set）区域内其它（如行数、列数）等。本类自身所有。3：其它等。事件：一般本身不发生事件，而由外部事件而触发（如save, 等）。与TextArea的区别：TextArea自身带有滚动杠，而JtextArea必须人工设置。例： class TextAreaDemo extends JFrame private JTextArea t1, t2; private JButton copy,cut,append;private JPanel jp1; publi

6、c TextAreaDemo() super( "TextArea Demo" ); Box b = Box.createHorizontalBox();Container c = getContentPane();jp1=new JPanel(); c.add( b ); / Box placed in BorderLayout.CENTER c.add(jp1,"North"); String s = "This is a demo string ton" + "illustrate copying textn"

7、; + "from one TextArea to n" + "another TextArea using ann"+ "external eventn" t1 = new JTextArea( s, 30, 20 ); b.add( new JScrollPane( t1 ) ); cut=new JButton( "cut" ); append=new JButton( "append" ); copy = new JButton( "Copy >>>"

8、; ); buttonhandle h1=new buttonhandle(); copy.addActionListener(h1); cut.addActionListener(h1); append.addActionListener(h1); jp1.add( copy );jp1.add( cut );jp1.add( append); t2 = new JTextArea( 10, 20 ); /t2.setEditable( false ); b.add( new JScrollPane( t2 ) ); / Container c = getContentPane(); / c

9、.add( b ); / Box placed in BorderLayout.CENTER setSize( 425, 200 ); show(); private class buttonhandle implements ActionListener public void actionPerformed( ActionEvent e )if(e.getSource()=copy)t2.setText( t1.getSelectedText() );else if(e.getSource()=cut)t1.cut();t2.cut();else if(e.getSource()=appe

10、nd)t2.append(t1.getSelectedText() );public class wcbtext public static void main( String args ) TextAreaDemo app = new TextAreaDemo(); /增加：全部copy, clear等功能。2：对话框：系统提供：消息框，文件对话框、选择颜色对话框等。用户设计。custom dialog1: 消息框: JOptionPane类：用于较简单的对话框，如：显示程序运行信息，提示用户简单输入等。它有四个static方法（分别用于设计四种最简单的对话框设计）。the static s

11、howXxxDialog methods shown below: showConfirmDialog Asks a confirming question, like yes/no/cancel. showInputDialog Prompt for some input. showMessageDialog Tell the user about something that has happened. showOptionDialog The Grand Unification of the above three. 例：JOptionPane.showMessageDialog(nul

12、l, "Eggs aren't supposed to be green.");The code for simple dialogs can be minimal. For example, here's an informational dialog: 当然：可以在字符串中显示程序运行的数据。如：int a=4,b=6,c;c=a*b;JOptionPane.showMessageDialog(null, "c=”+c );String inputValue = JOptionPane.showInputDialog("Please

13、input a value"); int number=Integer.parseInt(inputValue);Object possibleValues = "First", "Second", "Third" ;Object selectedValue = JOptionPane.showInputDialog(null, "Choose one", "Input",JOptionPane.INFORMATION_MESSAGE, null,possibleValues, pos

14、sibleValues0);if(selectedValue=possibleValues1)JOptionPane.showMessageDialog(null,"alert","alert",JOptionPane.ERROR_MESSAGE); 文件对话框: Two other classes, JColorChooser and JFileChooser, also supply standard dialogsJFileChooser: +- |+-主要方法：1：open文件,save文件intshowOpenDialog(Component&

15、#160;parent)           Pops up an "Open File" file chooser dialog. intshowSaveDialog(Component parent)           Pops up a "Save File" file chooser dialog注：parent:对话框的拥有类

16、：决定显示的位置。2：构造函数：Constructor SummaryJFileChooser()           Constructs a JFileChooser pointing to the user's default directory.JFileChooser(File currentDirectory)           Constructs a JFile

17、Chooser using the given File as the path.3：文件的操作方面，如：显示文件的方式，单选、多选文件等。例1：JFileChooser chooser = new JFileChooser();int returnVal = chooser.showOpenDialog(parent); if(returnVal = JFileChooser.APPROVE_OPTION) chooser.getSelectedFile().getName(); Parameters: parent - the parent component of the dialog;

18、 can be null Returns: the return state of the file chooser on popdown: · JFileChooser.CANCEL_OPTION · JFileChooser.APPROVE_OPTION · JFileCHooser.ERROR_OPTION if an error occurs or the dialog is dismissed The following code pops up a file chooser for the user's home directory that

19、sees only .jpg and .gif images: JFileChooser chooser = new JFileChooser(); / Note: source for ExampleFileFilter can be found in FileChooserDemo, / under the demo/jfc directory in the Java 2 SDK, Standard Edition. ExampleFileFilter filter = new ExampleFileFilter(); filter.addExtension("jpg"

20、); filter.addExtension("gif"); filter.setDescription("JPG & GIF Images"); chooser.setFileFilter(filter); int returnVal = chooser.showOpenDialog(parent); if(returnVal = JFileChooser.APPROVE_OPTION) chooser.getSelectedFile().getName(); Class JDialog | +- | +- | +- | +- | The re

21、st of this section covers the following topics: · An Overview of Dialogs · The DialogDemo Example · JOptionPane Features · Creating and Showing Simple Dialogs · Customizing Button Text · Getting the User's Input from a Dialog · Stopping Automatic Dialog Closing

22、 · The Dialog API · Examples that Use Dialogs An Overview of Dialogs Every dialog is dependent on a frame. When that frame is destroyed, so are its dependent dialogs. When the frame is iconified, its dependent dialogs disappear from the screen. When the frame is deiconified, its dependent

23、dialogs return to the screen. The AWT automatically provides this behavior. A dialog can be modal. When a modal dialog is visible, it blocks user input to all other windows in the program. The dialogs that JOptionPane provides are modal. To create a non-modal dialog, you must use the JDialog class directly. T