Java布局管理器使用方法探讨

1、Java布局管理器使用方法探讨文/毛永恒很多初学者在用Java布局器自动布局画界面时,经常遇见不知道如何定义区域大小或按钮之间的距离等问题。我写过一篇实现JAVA手动布局中各个组件能随窗口变化的方法的文章,有读者反映算坐标不好算,问能不能用布局器实现文章中的界面。其实自动布局也可以解决定义区域大小或按钮之间的距离等问题,只是没有手动布局那么灵活。下面我就举一个例子。首先,建一个frame文件(Application应用程序,在Design中将this中的layout设置为BorderLayout。第二,在组件盘内点选Swing Container页签,选取Jpanel图标,在this中上方拖拽

2、一块区域,布局器会自动调整位置与大小;同样的方法在中下方也拖拽一块区域;在Swing Container页签,选取jScrollPane图标,将jScrollPane在中间拖拽一块区域。拖拽的顺序一定要先上后下再中间。为了方便区分,在Properties的background中,将上方的Jpanel1区域设置为红色,下方的Jpanel2区域设置为橙色,中间的jScrollPane1为粉红色。将Jpanel1和Jpanel2的layout 设置为flowLayout(必须要手动设置,不要采用默认值。第三,在Jpanel中放入一个Jlable标题栏,JTextField1文本框和Jbutton按钮

3、,在组件盘内点选Swing 页签,选取JLable图标在Jpanel1的中画一个标题栏,将text改为“请输入查询条件”,再选取JtextField在Jpanel1中画一个文本框,将text 改为空,最后选取Jbutton在Jpanel1中再画一个按钮将text改为“查询”。画完后他们都是在中间,而且大小固定,这时点选Jpanel的flowLayout1将右边Properties 中的alignment设置为LEFT,这时Jpanel1中的组键就会向左排列。选中其中一个组键,在Properties中的preferredSize可以设置组键的宽和高。同样的方法在Jpanel2中画三个Jbutto

4、n按钮,将text分别设为“增加”、“删除”、“修改”。点选Jpane2的flowLayout2将右边Properties中的hgap设置为30(按钮的间距,可根据自己的需要调整数值大小, 这样就调整了三个按钮之间的距离,设置vgap还可以改变Jpane2区域的高度。第四,在jScrollPane1中建一个表格用来显示数据库数据的内容,在组件盘内点选Swing 页签,选取JTable图标,将Jtable加入到jScrollPane1中。最后,将this中的defaultCloseOperation改为EXIT_ON_CLOSE,这样在关闭窗口时程序会自动退出。程序源代码如下(除中文注释部分的两

5、句是自己加上去,其余是自动生成:import javax.swing.*;import java.awt.*;import java.awt.event.*;import java.util.Vector;import javax.swing.table.DefaultTableModel;public class Frame1 extends JFrameBorderLayout borderLayout1 = new BorderLayout(;JPanel jPanel1 = new JPanel(;JPanel jPanel2 = new JPanel(;JPanel jPanel3

6、= new JPanel(;JLabel jLabel1 = new JLabel(;JTextField jTextField1 = new JTextField(;JButton jButton1 = new JButton(;FlowLayout flowLayout1 = new FlowLayout(;FlowLayout flowLayout2 = new FlowLayout(;JButton jButton2 = new JButton(;JButton jButton3 = new JButton(;JButton jButton4 = new JButton(;GridLa

7、yout gridLayout1 = new GridLayout(;JScrollPane jScrollPane1 = new JScrollPane(;JTable jTable1 = new JTable(;public Frame1(try jbInit(; catch (Exception ee.printStackTrace(;public static void main(String argsFrame1 frame1 = new Frame1(;frame1.setSize(new Dimension(400, 350;frame1.show(;private void j

8、bInit( throws Exceptionthis.getContentPane(.setLayout(borderLayout1;jPanel1.setBackground(Color.red;jPanel1.setLayout(flowLayout1;jPanel2.setBackground(Color.red;jPanel2.setLayout(flowLayout2;jPanel3.setBackground(Color.pink;jPanel3.setLayout(gridLayout1;jLabel1.setPreferredSize(new Dimension(100, 1

9、6;jLabel1.setText("请输入查询条件"jTextField1.setPreferredSize(new Dimension(140, 22;jTextField1.setText(""jButton1.setText("查询"jButton1.addActionListener(new Frame1_jButton1_actionAdapter(this;flowLayout1.setAlignment(FlowLayout.LEFT;flowLayout1.setHgap(5;flowLayout1.setVgap(

10、10;jButton2.setText("增加"jButton3.setText("删除"jButton4.setText("修改"flowLayout2.setHgap(30;flowLayout2.setVgap(5;this.setDefaultCloseOperation(EXIT_ON_CLOSE;this.getContentPane(.add(jPanel1, BorderLayout.NORTH;jPanel1.add(jLabel1, null;jPanel1.add(jTextField1, null;jPanel

11、1.add(jButton1, null;this.getContentPane(.add(jPanel2, BorderLayout.SOUTH;jPanel2.add(jButton2, null;jPanel2.add(jButton3, null;jPanel2.add(jButton4, null;this.getContentPane(.add(jPanel3, BorderLayout.CENTER;jPanel3.add(jScrollPane1, null;jScrollPane1.getViewport(.add(jTable1, null;/模拟查询数据库void jBu

12、tton1_actionPerformed(ActionEvent etry /制作表Vector vcol = new Vector(; /列名Vector vrow = new Vector(; /内容for (int col = 1; col < 31; col+vcol.addElement("列" + col;for (int row = 1; row < 101; row+Vector vr1 = new Vector(;for (int col = 1; col < 31; col+vr1.addElement(row + "/&q

13、uot; + col;vrow.addElement(vr1;DefaultTableModel dtm = new DefaultTableModel(vrow, vcol;jTable1 = new JTable(vrow, vcol;jTable1.setAutoResizeMode(JTable.AUTO_RESIZE_OFF; /滚动条设置左右滚this.jScrollPane1.getViewport(.add(jTable1, null; /在滚动条中放入表 catch (Exception ex JOptionPane.showMessageDialog(null, ex; class Frame1_jButton1_actionAdapte