etext.java

Java 2实用编程百例,一些比较实用的J2SE小程序,可以通过这些程序熟悉JAVA基础知识

package ch06.section04;

import java.util.*;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class EText
    extends JApplet
    implements ItemListener {
  JLabel fontLabel, sizeLabel, styleLabel;
  FontPanel fontC;
  JComboBox fonts, sizes, styles;
  int index = 0;
  String fontchoice = "fontchoice";
  int stChoice = 0;
  String siChoice = "10";

  public void init() {

    getContentPane().setLayout(new BorderLayout());

    JPanel topPanel = new JPanel();
    JPanel fontPanel = new JPanel();
    JPanel sizePanel = new JPanel();
    JPanel stylePanel = new JPanel();
    JPanel sizeAndStylePanel = new JPanel();

    topPanel.setLayout(new BorderLayout());
    fontPanel.setLayout(new GridLayout(2, 1));
    sizePanel.setLayout(new GridLayout(2, 1));
    stylePanel.setLayout(new GridLayout(2, 1));
    sizeAndStylePanel.setLayout(new BorderLayout());

    topPanel.add(BorderLayout.WEST, fontPanel);
    sizeAndStylePanel.add(BorderLayout.WEST, sizePanel);
    sizeAndStylePanel.add(BorderLayout.CENTER, stylePanel);
    topPanel.add(BorderLayout.CENTER, sizeAndStylePanel);

    getContentPane().add(BorderLayout.NORTH, topPanel);

    fontLabel = new JLabel();
    fontLabel.setText("字体");
    Font newFont = getFont().deriveFont(1);
    fontLabel.setFont(newFont);
    fontLabel.setHorizontalAlignment(JLabel.CENTER);
    fontPanel.add(fontLabel);

    sizeLabel = new JLabel();
    sizeLabel.setText("字体大小");
    sizeLabel.setFont(newFont);
    sizeLabel.setHorizontalAlignment(JLabel.CENTER);
    sizePanel.add(sizeLabel);

    styleLabel = new JLabel();
    styleLabel.setText("字型");
    styleLabel.setFont(newFont);
    styleLabel.setHorizontalAlignment(JLabel.CENTER);
    stylePanel.add(styleLabel);

    //得到系统字体生成选择字体的ComboBox
    GraphicsEnvironment gEnv = GraphicsEnvironment.getLocalGraphicsEnvironment();
    String envfonts[] = gEnv.getAvailableFontFamilyNames();
    Vector vector = new Vector();
    for (int i = 1; i < envfonts.length; i++) {
      vector.addElement(envfonts[i]);
    }
    fonts = new JComboBox(vector);
    fonts.setMaximumRowCount(9);
    fonts.addItemListener(this);
    fontchoice = envfonts[0];
    fontPanel.add(fonts);

    //生成选择文字大小的ComboBox
    sizes = new JComboBox(new Object[] {"10", "12", "14", "16", "18", "20",
                          "24", "30"});
    sizes.setMaximumRowCount(9);
    sizes.addItemListener(this);
    sizePanel.add(sizes);
    //生成选择字型的ComboBox
    styles = new JComboBox(new Object[] {
                           "常规",
                           "粗体",
                           "倾斜",
                           "粗体 倾斜"});
    styles.setMaximumRowCount(9);
    styles.addItemListener(this);
    sizes.setMaximumRowCount(9);
    stylePanel.add(styles);

    fontC = new FontPanel();
    fontC.setBackground(Color.white);
    getContentPane().add(BorderLayout.CENTER, fontC);
  }

//获取用户对字体的选择
  public void itemStateChanged(ItemEvent e) {
    if (e.getStateChange() != ItemEvent.SELECTED) {
      return;
    }

    Object list = e.getSource();

    if (list == fonts) {
      fontchoice = (String) fonts.getSelectedItem();
    }
    else if (list == styles) {
      index = styles.getSelectedIndex();
      stChoice = index;
    }
    else {
      siChoice = (String) sizes.getSelectedItem();
    }
    fontC.changeFont(fontchoice, stChoice, siChoice);
  }

  public static void main(String s[]) {
    JFrame f = new JFrame("文字格式控制");
    f.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    JApplet fontSelection = new EText();
    f.getContentPane().add(fontSelection, BorderLayout.CENTER);
    fontSelection.init();
    f.setSize(new Dimension(550, 250));
    f.setVisible(true);
  }

}

class FontPanel
    extends JPanel {

  Font thisFont;

  public FontPanel() {
    thisFont = new Font("Arial", Font.PLAIN, 10);
  }

  //改变文字字体
  public void changeFont(String f, int st, String si) {
    Integer newSize = new Integer(si);
    int size = newSize.intValue();
    thisFont = new Font(f, st, size);
    repaint();
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;
    int w = getWidth();
    int h = getHeight();

    g2.setColor(Color.darkGray);
    g2.setFont(thisFont);
    String change = "Pick a font, size, and style to change me.";
    FontMetrics metrics = g2.getFontMetrics();
    int width = metrics.stringWidth(change);
    int height = metrics.getHeight();
    g2.drawString(change, w / 2 - width / 2, h / 2 - height / 2);

  }
}