/**系统的界面布局实现*/
GridBagConstraints gridBag = new GridBagConstraints();
gridBag.fill = GridBagConstraints.HORIZONTAL;  //以水平填充方式布局
    gridBag.weightx = 0;  //行长不变
    gridBag.weighty = 0;  //列高不变
    fromLabel.setForeground(Color.blue);
    fromLabel.setFont(new Font("Alias", Font.BOLD, 16));
    this.add(fromLabel, gridBag, 0, 1, 1, 1);  //指定发信人标签位置
    receiveLabel.setForeground(Color.blue);
    receiveLabel.setFont(new Font("Alias", Font.BOLD, 16));
    this.add(receiveLabel, gridBag, 0, 2, 1, 1); //指定收信人标签位置及大小
    ccLabel.setForeground(Color.blue);
    ccLabel.setFont(new Font("Alias", Font.BOLD, 16));
    this.add(ccLabel, gridBag, 0, 3, 1, 1); //指定抄送人标签位置及大小
    subjectLabel.setForeground(Color.blue);
    subjectLabel.setFont(new Font("Alias", Font.BOLD, 16));
    his.add(subjectLabel, gridBag, 0, 4, 1, 1); //指定主题标签位置及大小
    accessoryLabel.setForeground(Color.blue);
    accessoryLabel.setFont(new Font("Alias", Font.BOLD, 16));
    this.add(accessoryLabel, gridBag, 0, 5, 1, 1); //指定附件标签位置及大小

    gridBag.weightx = 100; //行自适应缩放
    gridBag.weighty = 0;//列高不变
    fromField.setText("admin@watermelon.com");
   	this.add(fromField, gridBag, 1, 1, 2, 1); //指定发信人文本域（JTextField）位置及大小
    this.add(receiveField, gridBag, 1, 2, 2, 1); //指定收信人文本域（JTextField）位置及大小
    this.add(ccField, gridBag, 1, 3, 2, 1); //指定抄送人文本域（JTextField）位置及大小
    this.add(subjectField, gridBag, 1, 4, 2, 1); //指定主题文本域（JTextField）位置及大小
    accessoryArea.setEditable(false); 
//设置不显示水平滚动条（该JTextArea置于JScrollPane中）
accessoryScroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
    this.add(accessoryScroll, gridBag, 1, 5, 2, 1); //指定附件文本区（JTextArea）位置及大小

    gridBag.fill = GridBagConstraints.BOTH;//采用全填充方式布局
    gridBag.weightx = 100;//行自适应缩放
    gridBag.weighty = 100;//列自适应缩放
    mailArea.setBackground(Color.blue);
    mailArea.setForeground(Color.yellow);
    mailArea.setTabSize(4);
    //指定信件主体区（JTextArea）的位置及大小。（该JTextArea也置于JScrollPane中）
	this.add(scroll, gridBag, 0, 6, 3, 1);

	在上面用到一个方法add()，这个方法是自己定义的：
private void add(Component c, GridBagConstraints gbc, int x, int y, int w, int h)
    {
        gbc.gridx = x;
        gbc.gridy = y;
        gbc.gridheight = h;
        gbc.gridwidth = w;
        this.getContentPane().add(c, gbc);
    }

JTabbedPane dbTabPane = new JTabbedPane();
…… //下面需要用到的JButton等组件变量定义（或声明）
private void initLayout()
{
initDBTabPane();//初始化JTabbedPane:DBTabPane组件
    this.getContentPane().add(BorderLayout.CENTER, dbTabPane);
	//将JTabbedPane组件：dbTabPane布局于JDialog对话框的中间
        initButtonPanel();//初始化JPanel:ButtonPanel组件
        this.getContentPane().add(BorderLayout.SOUTH, buttonPanel);
	//将JPanel组件：buttonPanel布局于JDialog对话框的底部（南面）
    }

private void initDBTabPane()
{
        JPanel loginPanel = new JPanel(new GridLayout(10, 1));
//为保证两个JCheckBox组件位于顶端，设置为共10行，每行一个组件的布局，但只
//放置界面要求的两个组件，这样就保持了界面的美观，否则如定义为
//Gridlayout(2,1)则会使两个组件居中，而且中间会隔开较长的距离。
pwdBox.setMnemonic('P');
        loginPanel.add(pwdBox);
        dspBox.setMnemonic('D');
        loginPanel.add(dspBox);
        dbTabPane.add("Login", loginPanel); //设置"Login"JPanel（图3.4-1）的布局
        needRadio.setMnemonic('N');
        allRadio.setMnemonic('A');
        cacheRadio.setMnemonic('U');
        radioPanel.setBorder(new TitledBorder("Load Option"));//加上边界标题
        radioPanel.add(needRadio);
        radioPanel.add(allRadio);
        radioPanel.add(cacheRadio);
//以上为加入需要的JRadioButton组件到指定的JPanel: radioPanel
        queryPanel.add(radioPanel);//加入含JRadioButton组的JPanel到queryPanel
        reqBox.setMnemonic('R');
        boxPanel.add(reqBox);
        saveBox.setMnemonic('S');
        boxPanel.add(saveBox);
        autoBox.setMnemonic('t');
        boxPanel.add(autoBox);
//以上为加入需要的JCheckBox组到指定的JPanel：boxPanel
        queryPanel.add(boxPanel); //加入含JCheckBox组的JPanel到queryPanel
        dbTabPane.add("Query", queryPanel);//设置"Query"JPanel（图3.4-2）的布局
        initDrvPanel();
    }

/**设置"Drivers"JPanel（图3.4-3）的布局*/
private void initDrvPanel()
{
        gridBag.fill = GridBagConstraints.HORIZONTAL;
        gridBag.weightx = 100;
        gridBag.weighty = 0;
        tipLabel.setForeground(Color.black);
        this.add(drvPanel, tipLabel, gridBag, 0, 0, 4, 1);
        urlLabel.setForeground(Color.black);
        this.add(drvPanel, urlLabel, gridBag, 0, 5, 4, 1);
        urlField.setEditable(false);
        this.add(drvPanel, urlField, gridBag, 0, 6, 4, 1);
        gridBag.weightx = 0;
        gridBag.weighty = 0;
        addButton.setMnemonic('A');
        this.add(drvPanel, addButton, gridBag, 3, 1, 1, 1);
        editButton.setMnemonic('E');
        this.add(drvPanel, editButton, gridBag, 3, 2, 1, 1);
        removeButton.setMnemonic('R');
        this.add(drvPanel, removeButton, gridBag, 3, 3, 1, 1);
        gridBag.fill = GridBagConstraints.BOTH;
        gridBag.weightx = 100;
        gridBag.weighty = 100;
       	//设置JTable组件：drvTable的从0到7行第0列的值
for (int i = 0; i < 8; i++)
       		drvTable.setValueAt(drvStrs[i],i,0); 
//设置JTable的列头
drvTable.getColumn(drvTable.getColumnName(0)).setHeaderValue("All Drivers");
        drvTable.setShowGrid(false);//设置不显示网格线
        this.add(drvPanel, drvScroll, gridBag, 0, 1, 3, 4);
        dbTabPane.add("Drivers", drvPanel);
   }

/**初始化底部JButton组的布局*/
private void initButtonPanel()
    {
        JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
//从右边开始进行FlowLayout布局
okButton.setMnemonic('O');
        buttonPanel.add(okButton);
        cancelButton.setMnemonic('C');
        buttonPanel.add(cancelButton);
        helpButton.setMnemonic('H');
        buttonPanel.add(helpButton);
    }

/**给指定的容器cn在指定的（x,y）位置放置指定大小（宽度=w,高度=h）的组件c*/
private void add(Container cn, Component c, GridBagConstraints gbc, int x, int y, int w, int h)
{
        gbc.gridx = x;
        gbc.gridy = y;
        gbc.gridwidth = w;
        gbc.gridheight = h;
        cn.add(c, gbc);
    }