Swing布局管理器介绍.doc

当选择使用JPanel和顶层容器的content pane时，需要考虑布局管理。JPanel缺省是初始化一个FlowLayout，而content pane缺省是初始化一个BorderLayout。下面将分别介绍几种最常用的布局管理器：FlowLayout、BorderLayout、BoxLayout、CardLayout、GridLayout和GridBagLayout。代码演示每一个布局管理器都会有一个代码演示，xxxLayoutDemo.java（见附件）。这些文件主要有三个方法组成：addComponentsToPane()提供布局逻辑（依据不同的布局管理器和UI内容）。publicstaticvoidaddComponentsToPane(Container pane) 。createAndShowGUI()实例化一个JFrame，通过它的ContentPane加载布局逻辑内容。privatestaticvoidcreateAndShowGUI() / Create and set up the window.JFrame frame =newJFrame(FlowLayoutDemo);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);/ Set up the content pane.addComponentsToPane(frame.getContentPane();/ Display the window.frame.pack();frame.setVisible(true);main()程序入口，单独起一个线程，实例化UI。publicstaticvoidmain(String args) javax.swing.SwingUtilities.invokeLater(newRunnable() publicvoidrun() createAndShowGUI(););FlowLayoutFlowLayout类是最简单的布局管理器。它按照和页面上排列单词的类似方式来安排组件-从左到右，直至没有多余的空间，然后转到下一行。效果：内容面板代码：publicstaticvoidaddComponentsToPane(Container pane) pane.setLayout(newFlowLayout();pane.add(newJButton(Button 1);pane.add(newJButton(Button 2);pane.add(newJButton(Button 3);pane.add(newJButton(Long-Named Button 4);pane.add(newJButton(5);BorderLayout一个BorderLayout对象将界面分成五大区域，分别用BorderLayout类的静态常量指定：-PAGE_START-PAGE_END-LINE_START-LINE_END-CENTER效果：内容面板代码：publicstaticvoidaddComponentsToPane(Container pane) JButton button =newJButton(Button 1 (PAGE_START);pane.add(button, BorderLayout.PAGE_START);button =newJButton(Button 2 (CENTER);button.setPreferredSize(newDimension(200, 100);pane.add(button, BorderLayout.CENTER);button =newJButton(Button 3 (LINE_START);pane.add(button, BorderLayout.LINE_START);button =newJButton(Long-Named Button 4 (PAGE_END);pane.add(button, BorderLayout.PAGE_END);button =newJButton(5 (LINE_END);pane.add(button, BorderLayout.LINE_END);BoxLayoutBoxLayout可以将组件由上至下或由左至右依次加入当前面板。效果：内容面板代码：publicstaticvoidaddComponentsToPane(Container pane) JPanel xPanel =newJPanel();xPanel.setLayout(newBoxLayout(xPanel, BoxLayout.X_AXIS);addButtons(xPanel);JPanel yPanel =newJPanel();yPanel.setLayout(newBoxLayout(yPanel, BoxLayout.Y_AXIS);addButtons(yPanel);pane.add(yPanel, BorderLayout.PAGE_START);pane.add(xPanel, BorderLayout.PAGE_END);privatestaticvoidaddAButton(String text, Container container) JButton button =newJButton(text);button.setAlignmentX(Component.CENTER_ALIGNMENT);container.add(button);privatestaticvoidaddButtons(Container container) addAButton(Button 1, container);addAButton(Button 2, container);addAButton(Button 3, container);addAButton(Long-Named Button 4, container);addAButton(5, container);CardLayout卡片布局和其他布局不同，因为它隐藏了一些组件。卡片布局就是一组容器或者组件，它们一次仅仅显是一个，组中的每个容器称为卡片。效果：内容面板代码：publicvoidaddComponentToPane(Container pane) finalJPanel contentPanel =newJPanel();JPanel controlPanel =newJPanel();finalCardLayout cardLayout=newCardLayout();pane.setLayout(newBorderLayout();pane.add(contentPanel, BorderLayout.CENTER);pane.add(controlPanel, BorderLayout.PAGE_END);controlPanel.setLayout(newFlowLayout();JButton b =newJButton10;for(inti = 0; i 10; i+) bi =newJButton(No.+ i);contentPanel.add(bi);contentPanel.setLayout(cardLayout);JButton nextButton =newJButton(next);nextButton.addActionListener(newActionListener()publicvoidactionPerformed(ActionEvent e) cardLayout.next(contentPanel););controlPanel.add(nextButton);GridLayoutGridLayout让你建立一个组件表格，并且当组件加入时，会依序又左至右，由上至下填充到每个格子，它不能由你指定想放那个格子就放那个格子效果：内容面板代码：publicstaticvoidaddComponentsToPane(Container pane) JButton buttons =newJButton9;pane.setLayout(newGridLayout(3, 3);for(inti = 0; i buttons.length; i+) buttonsi =newJButton(i +);pane.add(buttonsi);GridBagLayoutGridBagLayout是所有AWT布局管理器当中最复杂的，同时他的功能也是最强大的。GridBagLayout同GridLayout一样，在容器中以网格形式来管理组件。但GridBagLayout功能要来得强大得多。1、GridBagLayout管理的所有行和列都可以是大小不同的；2、GridLayout把每个组件限制到一个单元格，而GridBagLayout并不这样：组件在容器中可以占据任意大小的矩形区域。GridBagLayout通常由一个专用类来对他布局行为进行约束，该类叫GridBagConstraints。其中有11个公有成员变量，GridBagConstraints可以从这11个方面来进行控制和操纵。这些内容是：1、gridx组件的横向坐标；2、girdy组件的纵向坐标；3、gridwidth组件的横向宽度，也就是指组件占用的列数；4、gridheight组件的纵向长度，也就是指组件占用的行数；5、weightx指行的权重，告诉布局管理器如何分配额外的水平空间；6、weighty指列的权重，告诉布局管理器如何分配额外的垂直空间；7、anchor当组件小于其显示区域时使用此字段；8、fill如果显示区域比组件的区域大的时候，可以用来控制组件的行为。控制组件是垂直填充，还是水平填充，或者两个方向一起填充；9、insets指组件与表格空间四周边缘的空白区域的大小；10、ipadx组件间的横向间距，组件的宽度就是这个组件的最小宽度加上ipadx值；11、ipady组件间的纵向间距，组件的高度就是这个组件的最小高度加上ipady值。说明：1、gridx，gridy：其实就是组件行列的设置，注意都是从0开始的，比如gridx=0，gridy=1时放在0行1列；2、gridwidth，gridheight：默认值为1；GridBagConstraints.REMAINDER常量，代表此组件为此行或此列的最后一个组件，会占据所有剩余的空间；3、weightx，weighty：当窗口变大时，设置各组件跟着变大的比例。比如组件A的weightx=0.5，组件B的weightx=1，那么窗口X轴变大时剩余的空间就会以1：2的比例分配给组件A和B；4、anchor：当组件空间大于组件本身时，要将组件置于何处。有CENTER（默认值）、NORTH、NORTHEAST、EAST、SOUTHEAST、WEST、NORTHWEST选择。5、insets：设置组件之间彼此的间距。它有四个参数，分别是上，左，下，右，默认为（0，0，0，0）。效果：内容面板代码：publicstaticvoidaddComponentsToPane(Container pane) JButton button;pane.setLayout(newGridBagLayout();GridBagConstraints c =newGridBagConstraints();button =newJButton(Button 1);c.fill= GridBagConstraints.HORIZONTAL;c.gridx= 0;c.gridy= 0;pane.add(button, c);button =newJButton(Button 2);c.fill= GridBagConstraints.HORIZONTAL;c.weightx= 0.5;c.gridx= 1;c.gridy= 0;pane.add(button, c);button =newJButton(Button 3);c.fill= GridBagConstraints.HORIZONTAL;c.weightx= 0.5;c.gridx= 2;c.gridy= 0;pane.add(button, c);button =newJButton(Long-Named Button 4);c.fill= GridBagConstraints.HORIZONTAL;c.ipady= 40;/ make this component tallc.weightx= 0.0;c.gridwidth= 3;c.gridx= 0;c.gridy= 1;pane.add(button, c);button =newJButton(5);c.fill= GridBagConstraints.HORIZONTAL;c.ipady= 0;/ reset to defaultc.weighty= 1.0;/ request any extra vertical spacec.anchor= GridBagConstraints.PAGE_END;/ bottom of spacec.insets=newInsets(10, 0, 0, 0);/ top paddingc.gridx= 1;/ aligned with button 2c.gridwidth= 2;/ 2 columns widec.gridy= 2;/ third rowpane.add(button, c);一个GardBagLayout布局的左右选择框，代码GridBagLayoutFrame.java见附件，效果：GridBagLayoutFrame.java附件源码import java.awt.Dimension;import java.awt.GridBagConstraints;import java.awt.GridBagLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.BorderFactory;import javax.swing.DefaultListModel;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JList;import javax.swing.JPanel;import javax.swing.JTextField;public class GridBagLayoutFrame extends JFrame private static final long serialVersionUID = 6819222900970457455L;private JPanel mainPanel = new JPanel();private JButton addButton = new JButton();private JButton leftButton = new JButton();private JButton rightButton = new JButton();private JLabel label = new JLabel();private JTextField field = new JTextField();private DefaultListModel leftModel = new DefaultListModel();private DefaultListModel rightMOdel = new DefaultListModel();private JList leftList = new JList(leftModel);private JList rightList = new JList(rightMOdel);public GridBagLayoutFrame(String title) setTitle(GridBagLayoutFrameDemo);setPreferredSize(new Dimension(600, 400);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);initComponent();addData();pack();setVisible(true);private static void createAndShowGUI() new GridBagLayoutFrame(GridBagLayoutFrameDemo);private void initComponent() label.setText(添加选项：);addButton.setText(添加);leftList.setPreferredSize(new Dimension(150, 150);rightList.setPreferredSize(leftList.getPreferredSize();leftButton.setText(左);rightButton.setText(右);mainPanel.setBorder(BorderFactory.createTitledBorder(左右选择框);mainPanel.setLayout(new GridBagLayout();GridBagConstraints c = new GridBagConstraints();c.gridx = 0; / 0行0列c.gridy = 0;c.gridwidth = 1;c.gridheight = 1;c.fill = GridBagConstraints.HORIZONTAL;c.weightx = 0;c.weighty = 0;mainPanel.add(label, c);c.gridx+;c.weightx = 1;mainPanel.add(field, c);c.gridx+;c.weightx = 0;c.gridwidth = 1;c.gridheight = 1;/ c.fill = GridBagConstraints.HORIZONTAL;mainPanel.add(addButton, c);c.gridx = 0;c.gridy = 1;c.weightx = 1;c.weighty = 1;c.gridwidth = 2;c.gridheight = 2;c.fill = GridBagConstraints.BOTH;mainPanel.add(leftList, c);c.gridx = 2;c.gridy = 1;c.gridwidth = 1;c.gridheight = 1;c.weightx = 0;c.weighty = 0.5;c.anchor = GridBagConstraints.SOUTH;c.fill = GridBagConstraints.HORIZONTAL;mainPanel.add(leftButton, c);c.gridx = 2;c.gridy = 2;c.anchor = GridBagConstraints.NORTH;c.fill = GridBagConstraints.HORIZONTAL;mainPanel.add(rightButton, c);c.gridx = 3;c.gridy = 1;c.gridwidth = 1;c.gridheight = 2;c.weightx = 1;c.weighty = 1;c.fill = GridBagConstraints.BOTH;mainPanel.add(rightList, c);this.getContentPane().add(mainPanel);private void addData() addButton.addActionListener(new ActionListener() public void actionPerformed(ActionEvent e) addItem(););leftButton.addActionListener(new ActionListener() public void actionPerfo