Java2实用教程（第二版）程序代码——第二十四章 Java与多媒体

  1//例子1
  2import java.applet.*;import java.awt.*;
  3import java.awt.event.*;
  4public class Example24_1 extends Applet implements ActionListener
  5{  AudioClip clip;//声明一个音频对象
  6   Button button_play,button_loop,button_stop;
  7    public void init()
  8   {   clip=getAudioClip(getCodeBase(),"1.au");
  9      //根据程序所在的地址处的声音文件1.au创建音频对象，Applet类的
 10     // getCodeBase() 方法可以获得小程序所在的html页面的URL地址。
 11     button_play=new Button("开始播放");button_loop=new Button("循环播放");
 12     button_stop=new Button("停止播放");button_play.addActionListener(this);
 13     button_stop.addActionListener(this);button_loop.addActionListener(this); 
 14     add(button_play);add(button_loop);add(button_stop);   
 15    } 
 16    public void stop()
 17    {  clip.stop();//当离开此页面时停止播放。
 18    }
 19    public void actionPerformed(ActionEvent e)
 20    {  if(e.getSource()==button_play)
 21        { clip.play();}
 22       else if(e.getSource()==button_loop)
 23       { clip.loop();}
 24      if(e.getSource()==button_stop)
 25       { clip.stop();} 
 26   }
 27}
 28
 29//例子2
 30import java.applet.*;import java.awt.*;import java.awt.event.*;
 31public class Example24_2 extends Applet implements ActionListener,Runnable,ItemListener
 32{  AudioClip clip;//声明一个音频对象。
 33   Choice choice;
 34   TextField text;
 35   Thread thread;
 36   String item=null;
 37   Button button_play,button_loop,button_stop;
 38   public void init()
 39  {  choice=new Choice();
 40     thread=new Thread(this); 
 41     int N=Integer.parseInt(getParameter("总数"));
 42     for(int i=1;i<=N;i++)
 43       {  choice.add(getParameter(String.valueOf(i)));  
 44       } 
 45    button_play=new Button("开始播放");  
 46    button_loop=new Button("循环播放");
 47    button_stop=new Button("停止播放");  
 48    text=new TextField(12);
 49    button_play.addActionListener(this);  
 50    button_stop.addActionListener(this);
 51    button_loop.addActionListener(this);   
 52    choice.addItemListener(this);
 53    add(choice);
 54    add(button_play);add(button_loop);add(button_stop); add(text);  
 55    button_play.setEnabled(false);
 56    button_loop.setEnabled(false); 
 57  } 
 58  public void itemStateChanged(ItemEvent e)
 59  { item=choice.getSelectedItem();
 60    int index=item.indexOf(":");
 61    item=item.substring(index+1).trim();
 62    if(!(thread.isAlive()))
 63     {  thread=new Thread(this); 
 64     } 
 65    try {
 66         thread.start();
 67        }
 68    catch(Exception exp)
 69        { text.setText("正在下载音频文件");
 70        }
 71  }
 72 public void stop()
 73 {  clip.stop();
 74 }
 75 public void actionPerformed(ActionEvent e)
 76 {  if(e.getSource()==button_play)
 77      { clip.play();
 78      }
 79    else if(e.getSource()==button_loop)
 80      { clip.loop();
 81      }
 82    else if(e.getSource()==button_stop)
 83      { clip.stop();
 84        button_play.setEnabled(false);
 85        button_loop.setEnabled(false);
 86      } 
 87 }
 88 public void run()
 89 { 
 90    clip=getAudioClip(getCodeBase(),item);
 91    text.setText("请稍等");
 92     if(clip!=null)
 93    {  button_play.setEnabled(true);
 94       button_loop.setEnabled(true);
 95       text.setText("您可以播放了");
 96    } 
 97 }
 98}
 99
100//例子3
101import java.applet.*;import java.awt.*;
102import java.net.*;import java.awt.event.*;
103import java.io.*;import javax.media.*;
104public class Example24_3 extends Applet
105         implements ControllerListener,Runnable,ItemListener
106{  Player player;
107   String str; 
108   Thread mythread;
109   Choice choice;
110   Component visualComponent,controlComponent,progressBar;
111   String mediaFile;
112   URL mediaURL,codeBase;
113   Frame frame;
114   public void init()
115   { str="Music01.MPG"; 
116     mythread=new Thread(this);
117     choice=new Choice();
118     choice.add("Music01.MPG");
119     choice.add("Music02.avi");
120     choice.add("Music03.avi");
121     choice.addItemListener(this);
122     codeBase=getDocumentBase();
123     frame=new Frame("视频系统");
124     frame.setSize(660,580);
125     frame.addWindowListener(new WindowAdapter()
126            {  public void windowClosing(WindowEvent e)
127               {  if(player!=null)
128                    { player.stop();player.deallocate(); 
129                    }
130                 frame.setVisible(false);
131                 System.exit(0);
132               } 
133            });
134     add(choice);
135   } 
136   public void stop()
137   {  if(player!=null)
138      { player.stop();
139      }
140   }
141   public synchronized void controllerUpdate(ControllerEvent event)
142   {   player.getDuration();
143      if(event  instanceof  RealizeCompleteEvent)
144        { if((visualComponent=player.getVisualComponent())!=null)
145                 frame.add("Center",visualComponent);
146          if((controlComponent=player.getControlPanelComponent())!=null)
147                if(visualComponent!=null)
148                     frame.add("South",controlComponent);
149                else
150                     frame.add( "Center",controlComponent);
151          frame.validate();
152          frame.pack();
153        }
154     else if(event  instanceof  PrefetchCompleteEvent)
155        {  player.start(); 
156        }
157   }
158   public void itemStateChanged(ItemEvent e)
159   {  
160      str=choice.getSelectedItem();
161      if(player==null)
162         {
163         }
164      else
165         { player.stop();player.deallocate(); 
166         }
167      frame.removeAll();
168      frame.setVisible(true);
169      frame.setBounds(300,100,150,100);
170      frame.validate();
171      if(!(mythread.isAlive()))
172         {  mythread=new Thread(this);
173         }
174      try{
175            mythread.start();
176         }
177      catch(Exception ee)
178         {
179         }
180   }
181   public synchronized void run()
182   {  try{  mediaURL=new URL(codeBase,str);
183            player=Manager.createPlayer(mediaURL);player.getDuration();
184            if(player!=null)
185             {  player.addControllerListener(this);
186             }
187           else
188             System.out.println("failed to creat player for"+mediaURL);
189       }
190     catch(MalformedURLException e)
191       {  System.out.println("URL for"+mediaFile+"is invalid");
192       }
193      catch(IOException e)
194       {  System.out.println("URL for"+mediaFile+"is invalid");
195       }
196     catch(NoPlayerException e)
197       { System.out.println("canot find a player for"+mediaURL);
198       }
199     if(player!=null)
200       { player.prefetch(); 
201       }
202   }
203}
204