Java_GUI_2

import java.awt.Container;
import java.awt.Font;
import java.awt.GraphicsEnvironment;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

//主类
public class ComboBox
{

    public static void main(String[] args)
    {
        //      实例化框架类
        GUIFrame frame = new GUIFrame();
        //      设置默认关闭方式
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //      显示框架
        frame.setVisible(true);//推荐使用等同frame.show();
    }
}

//框架类

class GUIFrame extends JFrame
{
    public GUIFrame()
    {
        setTitle("J组件介绍");//设置框架标题
        setSize(640, 480);//设置大小

        Container con = getContentPane();//取得内容窗格
        GUIPanel panel = new GUIPanel();//实例化面板
        con.add(panel);//将面板类添加到内容窗格
    }
}

//面板类

class GUIPanel extends JPanel
{
    private JLabel label;//声明全局变量

    private JComboBox cfont, cstyle, csize;//声明全局变量

    public GUIPanel()
    {
        label = new JLabel("欢迎来到JAVA世界!!!");//标签

        //组合框
        String[] fonts = GraphicsEnvironment.getLocalGraphicsEnvironment()
                .getAvailableFontFamilyNames();//取得当前操作系统的所有字体
        String[] style =
        { "常规", "加粗", "倾斜", "粗斜" };

        cfont = new JComboBox(fonts);
        cstyle = new JComboBox(style);
        csize = new JComboBox(new String[]
        { "12", "16", "18", "22", "26", "32", "48" });

        cfont.addActionListener(new ActionListener()//动作监听
        {
            public void actionPerformed(ActionEvent e)
            {
                String fontName = cfont.getSelectedItem().toString();
                Font oldFont = label.getFont();
                label.setFont(new Font(fontName, oldFont.getStyle(), oldFont
                        .getSize()));
            }
        });
        cstyle.addActionListener(new ActionListener()//动作监听
        {
            public void actionPerformed(ActionEvent e)
            {
                String fontStyle = cstyle.getSelectedItem().toString();
                Font oldFont = label.getFont();
                Font f = null;
                if ("常规".equals(fontStyle))
                {
                    f = new Font(oldFont.getFontName(), Font.PLAIN, oldFont
                            .getSize());
                }
                if ("加粗".equals(fontStyle))
                {
                    f = new Font(oldFont.getFontName(), Font.BOLD, oldFont
                            .getSize());
                }
                if ("倾斜".equals(fontStyle))
                {
                    f = new Font(oldFont.getFontName(), Font.ITALIC, oldFont
                            .getSize());
                }
                if ("粗斜".equals(fontStyle))
                {
                    f = new Font(oldFont.getFontName(),
                            Font.BOLD + Font.ITALIC, oldFont.getSize());
                }
                label.setFont(f);
            }
        });
        csize.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                String size = csize.getSelectedItem().toString();
                Font oldFont = label.getFont();
                int fontSize = Integer.parseInt(size);
                label.setFont(new Font(oldFont.getFontName(), oldFont
                        .getStyle(), fontSize));
            }
        });
        add(label);
        add(cfont);
        add(cstyle);
        add(csize);
    }
}