Java多媒体编程应用

1. 声音文件的播放

1.1 在Applet中播放声音

在Applet中，可以使用AudioClip来播放声音，它非常简单，只有三个方法：play()、loop()和stop()。

例1.1 利用AudioClip播放声音文件。

package duomeiti;

import java.applet.Applet;
import java.applet.AudioClip;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;

public class playMusic extends Applet implements ActionListener {
    AudioClip clip = null;
    JButton playBtn,loopBtn,stopBtn;
    public void init(){
        playBtn = new JButton("播放");
        loopBtn = new JButton("循环");
        stopBtn = new JButton("停止");
        playBtn.addActionListener(this);
        loopBtn.addActionListener(this);
        stopBtn.addActionListener(this);
        add(playBtn);
        add(loopBtn);
        add(stopBtn);
        clip = getAudioClip(getCodeBase(),"test.wav");
    }

    public void actionPerformed(ActionEvent e) {
        if(e.getSource()==playBtn)
            clip.play();
        else if(e.getSource()==loopBtn)
            clip.loop();
        else
            clip.stop();
    }
}

1.2 在Application中播放声音

它的一般用法是，先用AudioStream创建一个音频流对象，而后将此对象作为参数传递给AudioPlayer.player.start()方法以便播放。虽然AudioPlayer.player中只有start()和stop()两个方法，但是start()方法会从音频流对象上次停止播放的位置开始播放，而不是从头开始播放。所以用stop()暂停一个音频流的播放后，可以使用start()继续播放。

例1.2 在Application中播放声音文件。

package duomeiti;

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import javax.swing.*;

import sun.audio.AudioPlayer;
import sun.audio.AudioStream;
public class playAudio implements ActionListener {
    protected JTextField fileField;
    protected JButton openBtn,startBtn,pauseBtn,resumBtn,stopBtn;
    protected Container con;
    protected JFrame jf;
    protected AudioStream as;
    protected FileInputStream fis;

    public playAudio(){
        jf = new JFrame("播放声音");
        con = jf.getContentPane();
        con.setLayout(new FlowLayout());
        fileField = new JTextField();
        fileField.setColumns(30);
        openBtn = new JButton("选择文件");
        startBtn = new JButton("开始播放");
        pauseBtn = new JButton("暂停播放");
        resumBtn = new JButton("继续播放");
        stopBtn = new JButton("停止播放");
        openBtn.addActionListener(this);
        startBtn.addActionListener(this);
        pauseBtn.addActionListener(this);
        resumBtn.addActionListener(this);
        stopBtn.addActionListener(this);
        con.add(fileField);
        con.add(openBtn);
        con.add(startBtn);
        con.add(pauseBtn);
        con.add(resumBtn);
        con.add(stopBtn);
        jf.setSize(500, 400);
        jf.setLocation(300, 200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    
    public void actionPerformed(ActionEvent e) {
        Object obj;
        obj = e.getSource();
        try {
            if(obj==openBtn)
                openfile();
            else if(obj==startBtn){
                if(fis!=null) fis.close();
                fis = new FileInputStream(fileField.getText());
                as = new AudioStream(fis);
                AudioPlayer.player.start(as);
            }else if(obj==pauseBtn)
                AudioPlayer.player.stop(as);
            else if(obj==resumBtn)
                AudioPlayer.player.start(as);
            else if(obj==stopBtn){
                AudioPlayer.player.stop(as);
                as.close();
                fis.close();
                fis = null;
            }
        } catch (FileNotFoundException e1) {
            JOptionPane.showMessageDialog(jf, "文件没有找到！");
        } catch (IOException e1) {
            JOptionPane.showMessageDialog(jf, "无法播放文件！");
        }
    }

    private void openfile() {
        try {
            JFileChooser chooser = new JFileChooser();
            if(chooser.showOpenDialog(jf)==JFileChooser.APPROVE_OPTION)
                fileField.setText(chooser.getSelectedFile().toString());
        } catch (Exception e) {
            JOptionPane.showMessageDialog(jf, "无法加载文件！");
        }        
    }

    public static void main(String[] args) {
        new playAudio();
    }
}

 2. 基本图形处理

2.1 图形的缩放

例2.1 缩放图形示例

package duomeiti;
import java.awt.Color;
import java.awt.Graphics;

import javax.swing.*;
public class ResizeOval {
    JFrame jf;
    MyCanvas palette;
    public class MyCanvas extends JPanel{
        protected void paintComponent(Graphics g) {
            int height,width;
            height = getHeight();
            width = getWidth();
            g.setColor(Color.RED);
            g.fillOval(0, 0, width, height);
        }    
    }
    
    public ResizeOval(){
        jf = new JFrame("图形缩放示例");
        palette = new MyCanvas();
        jf.getContentPane().add(palette);
        jf.setSize(500, 400);
        jf.setLocation(300,200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public static void main(String[] args) {
        new ResizeOval();
    }
}

2.2 淡入淡出效果

要实现淡入淡出效果方法非常简单，只要采用HSB（色调-饱和度-亮度）模式设置色彩，其中的色调和亮度不必变化，只要调整饱和度的值即可。如果是淡入，则让饱和度逐步增加；如果是淡出，则让饱和度逐步减少。

例2.2 淡入淡出效果示例。

package duomeiti;
import java.awt.Color;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;
public class fadeInOut {
    JFrame jf;
    JPanel jp;
    Container con;
    dealPushBtn handleBtn;
    JButton btn;
    
    public class dealPushBtn implements ActionListener{
        public void actionPerformed(ActionEvent e) {
            Graphics g = jp.getGraphics();
            float h = 0.0f;
            float s = 0.0f;
            float b = 1.0f;
            for(int i=0;i<100;i++){
                g.setColor(Color.getHSBColor(h, s, b));
                g.fillRect(0, 50, 300, 300);
                try {
                    Thread.sleep(50);
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                }
                s+=0.01;
            }
            for(int i=0;i<100;i++){
                g.setColor(Color.getHSBColor(h, s, b));
                g.fillRect(0, 50, 300, 300);
                try {
                    Thread.sleep(50);
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                }
                s-=0.01;
            }            
        }
    }
    
    public fadeInOut(){
        jf = new JFrame("色彩淡入淡出示例");
        jp = new JPanel();
        jp.setLayout(new FlowLayout());
        handleBtn = new dealPushBtn();
        btn= new JButton("开始");
        btn.addActionListener(handleBtn);
        con = jf.getContentPane();
        jp.add(btn);
        con.add(jp);
        jf.setSize(300, 300);
        jf.setLocation(300, 200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public static void main(String[] args) {
        new fadeInOut();

    }

}

2.3  透明效果

设置前景色的透明度，可以使得前景色和后景色能够混合起来，这需要使用Graphics2D类。

例2.3 色彩混合效果示例。

package duomeiti;
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Composite;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;

import javax.swing.*;
public class TransparencyExample extends JPanel {
    private static int gap=10, width=40, offset=10,deltax=gap+width+offset;
    private Rectangle blueSquare = new Rectangle(gap+offset,gap+offset,width,width),
            redSquare = new Rectangle(gap,gap,width,width);
    //创建一个指定alpha值的AlphaComposite对象
    private AlphaComposite makeComposite(float alpha){
        int type = AlphaComposite.SRC_OVER;
        return (AlphaComposite.getInstance(type, alpha));
    }
    //用指定的alpha值来绘制前景色
    private void drawSquares(Graphics2D g2d,float alpha){
        Composite originalComposite = g2d.getComposite();
        //用默认透明度绘制背景蓝色
        g2d.setPaint(Color.blue);
        g2d.fill(blueSquare);
        //设置透明度，准备绘制前景红色
        g2d.setComposite(makeComposite(alpha));
        g2d.setPaint(Color.red);
        g2d.fill(redSquare);
        //将透明度设置回默认的模式
        g2d.setComposite(originalComposite);
    }
    //分别用不同的透明度来绘制颜色
    public void paintComponent(Graphics g){
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D)g;
        for(int i=0;i<11;i++){
            //alpha值逐步增大，透明度逐步减小
            drawSquares(g2d,i*0.1F);
            g2d.translate(deltax, 0);
        }
    }
}

package duomeiti;
import javax.swing.*;
import java.awt.*;
public class mixing {
    JFrame jf;
    TransparencyExample palette;
    public mixing(){
        jf = new JFrame("色彩混合示例");
        palette = new TransparencyExample();
        jf.getContentPane().add(palette);
        jf.setSize(700, 400);
        jf.setLocation(300, 200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public static void main(String[] args) {
        new mixing();
    }
}

3. 字体的处理

3.1 确定可用字体

例3.1 获取系统中安装的字体示例。

package duomeiti;
import java.awt.GraphicsEnvironment;

import javax.swing.*;
public class GetFonts {
    private JFrame jf;
    private JList nameList;
    private JScrollPane nameSPane;
    public GetFonts(){
        jf = new JFrame("获取系统字体");
        //获得GraphicsEnvironment类型的对象引用
        GraphicsEnvironment eq = GraphicsEnvironment.getLocalGraphicsEnvironment();
        //获取所有的字体家族名
        String[] availableFonts = eq.getAvailableFontFamilyNames();
        //存放到列表框中
        nameList = new JList(availableFonts);
        nameSPane = new JScrollPane(nameList);
        jf.add(nameSPane);
        jf.setSize(500, 400);
        jf.setLocation(300, 200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public static void main(String[] args) {
        new GetFonts();
    }
}

3.2 创建字体对象

例3.2 创建和使用字体示例。

package duomeiti;
import javax.swing.*;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class ShowFonts implements ActionListener {
    private JFrame jf;
    private JComboBox nameBox,styleBox;
    private JTextField sizeText;
    private JLabel fontLabel;
    private JButton showBtn;
    private JPanel panel;
    
    public ShowFonts(){
        jf = new JFrame("显示指定字体");
        //显示系统可用字体
        GraphicsEnvironment eq = GraphicsEnvironment.getLocalGraphicsEnvironment();
        String[] availableFonts = eq.getAvailableFontFamilyNames();
        nameBox = new JComboBox(availableFonts);
        nameBox.setEditable(true);
        nameBox.setSelectedItem("宋体");
        //显示字体风格由用户选择
        String[] style = {"正常","粗体","斜体","粗斜体"};
        styleBox = new JComboBox(style);
        styleBox.setEditable(false);
        //由用户输入想要的字体尺寸
        sizeText = new JTextField("12");
        sizeText.setColumns(4);
        //标签用于显示用户选择的字体
        fontLabel = new JLabel("字体示例");
        //创建按钮并安装监听器
        showBtn = new JButton("显示字体");
        showBtn.addActionListener(this);
        //在窗口中排列组件
        panel = new JPanel();
        panel.setLayout(new FlowLayout());
        panel.add(nameBox);
        panel.add(styleBox);
        panel.add(sizeText);
        jf.add(panel, BorderLayout.NORTH);
        jf.add(fontLabel, BorderLayout.CENTER);
        jf.add(showBtn, BorderLayout.SOUTH);
        jf.setSize(500, 400);
        jf.setLocation(300, 200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void actionPerformed(ActionEvent e) {
        //分别获取用户选择输入的字体信息
        int styleIndex = styleBox.getSelectedIndex();
        String fontStr = (String)nameBox.getSelectedItem();
        int fontSize = Integer.parseInt(sizeText.getText());
        //组合字体对象
        Font userFont = new Font(fontStr,styleIndex,fontSize);
        //为标签设置新的字体并显示
        fontLabel.setFont(userFont);
        
    }

    public static void main(String[] args) {
        new ShowFonts();
    }
}

4. 字体的展示处理

例4.1 自行管理字体示例。

package duomeiti;
import javax.swing.*;
import java.awt.*;
public class FontsCanvas extends JPanel {
    private String msg;
    public FontsCanvas(String s){
        msg = s;
        setBackground(Color.white);
    }
    
    public FontsCanvas(){
        this("自行管理字体示例");
    }
    
    public void paintComponent(Graphics g){
        int maxWidth = getWidth(); //获取画布的宽度
        int showX; //文字输出的横坐标位置
        int showY = 0; //文字输出的纵坐标位置
        int descent = 0; //文字下半部所占位置
        int ascent = 0; //文字上半部所占位置
        int leading = 0; //行间距
        int totalWidth; //字符串所占宽度
        FontMetrics fm; //用于自行管理字体
        Font myFonts [] = new Font[4];
        //创建不同的字体准备显示
        myFonts[0] = new Font("宋体",Font.PLAIN,12);
        myFonts[1] = new Font("仿宋",Font.BOLD,24);
        myFonts[2] = new Font("黑体",Font.ITALIC,48);
        myFonts[3] = new Font("楷体_GB2312",Font.ITALIC|Font.BOLD,60);
        //用上述4种不同的字体显示同一个字符串，右对齐
        for(int i=0;i<myFonts.length;i++){
            g.setFont(myFonts[i]);
            fm = g.getFontMetrics();
            totalWidth = fm.stringWidth(msg);
            showX = maxWidth - totalWidth;
            ascent = fm.getMaxAscent();
            showY = showY + descent + ascent + leading;
            descent = fm.getMaxDescent();
            leading = fm.getLeading();
            g.drawString(msg, showX, showY);
        }
    }
}

package duomeiti;
import javax.swing.*;
import java.awt.*;
public class ManageFonts {
    private JFrame jf;
    private FontsCanvas palette; //可以显示多种文字的画布
    public ManageFonts(){
        jf = new JFrame("自行管理字体示例");
        palette = new FontsCanvas();
        jf.add(palette);
        jf.setSize(500, 400);
        jf.setLocation(300, 200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    
    public static void main(String[] args) {
        new ManageFonts();
    }
}

5. 字体的特效显示

例5.1 字体特效显示示例。

package duomeiti;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.*;
public class LightingLiteral implements ActionListener {
    String title = "光照文字";    //显示的文字
    Font myFont = new Font("宋体",Font.BOLD,48); //显示的字体
    JPanel palette;
    JFrame jf;
    JButton startBtn;
    Container con;
    Timer myTimer;
    Refresh task;
    boolean startFlag;
    public LightingLiteral(){
        jf = new JFrame(title);
        palette = new JPanel();
        startBtn = new JButton("开始");
        startFlag = true;
        startBtn.addActionListener(this);
        con = jf.getContentPane();
        con.add(palette, BorderLayout.CENTER);
        con.add(startBtn, BorderLayout.NORTH);
        jf.setSize(500, 400);
        jf.setLocation(300, 200);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    
    public void actionPerformed(ActionEvent e) {
        if(startFlag){
            myTimer = new Timer();
            task = new Refresh();
            myTimer.schedule(task, 50, 50);  //启动定时器，时间间隔为50毫秒
            startBtn.setText("停止");
        }else{
            myTimer.cancel();
            myTimer = null;
            task = null;
            startBtn.setText("开始");
        }
        startFlag = !startFlag;
    }

    //用定时器来绘图
    class Refresh extends TimerTask{
        int pos = 0;
        int blink_width = 20;                //光条的宽度
        Graphics g = palette.getGraphics();  //注意画笔的获取方式
        FontMetrics myFM = g.getFontMetrics(myFont);
        int height = myFM.getHeight();  //计算文字的高度
        int top = myFM.getAscent();
        int width = myFM.stringWidth(title);
        public Refresh(){
            g.setFont(myFont);
        }
        public void run() {
            g.setColor(Color.blue);
            g.drawString(title, 0, top);  //第一遍显示
            g.clipRect(pos, 0, blink_width, height);  //设置裁剪区域
            g.setColor(Color.yellow);
            g.drawString(title, 0, top);  //第二遍显示，它只会显示在裁剪区域中
            pos = (pos + 5) % width;  //移动裁剪区域的位置
            g.setClip(null);  //让裁剪区域失效，准备重新绘制蓝色文字
        }
    }
    
    public static void main(String[] args) {
        new LightingLiteral();
    }
}