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();

    }

}