第54章、播放音頻（從零開始學Android）

現代智能手機無論是android、IOS、Windows phone8，其媒體播放器都是必不可少。

Android的MediaPlayer包含了Audio和video的播放功能，本案例我們學習如何使用Android的MediaPlayer播放MP3。

 

一、設計界面

1、首先把play.png、pause.png、stop.png三張圖片復制到res/drawable-hdpi文件夾內。

2、再者把coffee.mp3復制到res/raw文件夾內。

3、布局文件

打開activity_main.xml文件。

輸入以下代碼：

[html] view plain copy  

1. <?xml version="1.0" encoding="utf-8"?>  
2.   
3. <LinearLayout   
4.     xmlns:android="http://schemas.android.com/apk/res/android"  
5.     android:layout_width="match_parent"     
6.     android:layout_height="match_parent"     
7.     android:orientation="vertical">     
8.       
9.     <ImageButton       
10.         android:id="@+id/play"       
11.         android:layout_width="wrap_content"       
12.         android:layout_height="wrap_content"       
13.         android:src="@drawable/play" />   
14.          
15.               
16.     <ImageButton       
17.         android:id="@+id/pause"       
18.         android:layout_width="wrap_content"       
19.         android:layout_height="wrap_content"     
20.         android:src="@drawable/pause" />   
21.       
22.               
23.     <ImageButton       
24.         android:id="@+id/stop"       
25.         android:layout_width="wrap_content"       
26.         android:layout_height="wrap_content"    
27.         android:src="@drawable/stop" />   
28.           
29.     <TextView       
30.         android:id="@+id/prompt"       
31.         android:layout_width="wrap_content"       
32.         android:layout_height="wrap_content"       
33.         android:text="提示信息" />  
34.   
35. </LinearLayout>   

二、程序文件

打開“src/com.genwoxue.mp3/MainActivity.java”文件。

然後輸入以下代碼：

[java] view plain copy  

1. package com.genwoxue.mp3;  
2.   
3. import android.app.Activity;   
4. import android.os.Bundle;  
5. import android.media.MediaPlayer;  
6. import android.view.View;   
7. import android.widget.ImageButton;   
8. import android.widget.TextView;   
9.   
10.   
11. public class MainActivity extends Activity {  
12.       
13.       private ImageButton btnPlay,btnPause,btnStop;     
14.       private TextView tvPrompt;     
15.       private MediaPlayer mpPlayer;     
16.         
17.       //聲明一個變量判斷是否為暫停,默認為false     
18.       private boolean isPaused = false;     
19.         
20.       public void onCreate(Bundle savedInstanceState) {  
21.           super.onCreate(savedInstanceState);            
22.           setContentView(R.layout.activity_main);     
23.             
24.           //獲得btnPlay、btnPause、btnStop和tvPrompt通過findViewById找到資源           
25.           btnPlay = (ImageButton)findViewById(R.id.play);            
26.           btnPause = (ImageButton)findViewById(R.id.pause);            
27.           btnStop = (ImageButton)findViewById(R.id.stop);            
28.           tvPrompt = (TextView)findViewById(R.id.prompt);    
29.             
30.           //創建MediaPlayer對象,將raw文件夾下的coffee.mp3            
31.           mpPlayer = MediaPlayer.create(this,R.raw.coffee);            
32.             
33.           //設置播放監聽事件          
34.           btnPlay.setOnClickListener(new ImageButton.OnClickListener(){       
35.               @Override      
36.               public void onClick(View v) {        
37.                   try {              
38.                       if(mpPlayer != null){  
39.                           mpPlayer.stop();         
40.                       }             
41.                         
42.                       mpPlayer.prepare();         
43.                       mpPlayer.start();         
44.                       tvPrompt.setText("音樂播放中...");        
45.                   }   
46.                   catch (Exception e) {         
47.                       tvPrompt.setText("播放發生異常...");         
48.                       e.printStackTrace();        
49.                   }           
50.              }                  
51.           });                      
52.             
53.           //設置暫停監聽事件          
54.           btnPause.setOnClickListener(new ImageButton.OnClickListener(){       
55.               @Override      
56.               public void onClick(View v) {        
57.                   try {         
58.                       if(mpPlayer !=null){          
59.                           mpPlayer.stop();          
60.                           tvPrompt.setText("音樂停止播放...");         
61.                        }        
62.                   }  
63.                   catch (Exception e) {         
64.                       tvPrompt.setText("音樂停止發生異常...");         
65.                       e.printStackTrace();        
66.                   }             
67.               }                     
68.           });                      
69.             
70.           //設置停止監聽事件          
71.           btnStop.setOnClickListener(new ImageButton.OnClickListener(){       
72.               @Override      
73.               public void onClick(View v) {        
74.                   try {         
75.                       if(mpPlayer !=null){          
76.                           if(isPaused==false){           
77.                               mpPlayer.pause();           
78.                               isPaused=true;           
79.                               tvPrompt.setText("停止播放!");          
80.                           }          
81.                           else if(isPaused==true){           
82.                               mpPlayer.start();           
83.                               isPaused = false;           
84.                               tvPrompt.setText("開始播發!");          
85.                           }        
86.                       }        
87.                    }   
88.                   catch (Exception e) {         
89.                       tvPrompt.setText("發生異常...");         
90.                       e.printStackTrace();        
91.                    }             
92.             }                     
93.           });                     
94.             
95.           //設置MediaPlayer播放完畢事件　　  
96.           mpPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener(){               
97.               // @Override               
98.               public void onCompletion(MediaPlayer arg0){                 
99.                   try{                   
100.                       //釋放MediaPlayer資源                 
101.                       mpPlayer.release();                   
102.                       tvPrompt.setText("音樂播發結束!");                 
103.                   }                 
104.                   catch (Exception e){                   
105.                       tvPrompt.setText(e.toString());                   
106.                       e.printStackTrace();                 
107.                   }               
108.               }             
109.            });                        
110.             
111.           //設置MediaPlayer錯誤監聽事件           
112.           mpPlayer.setOnErrorListener(new MediaPlayer.OnErrorListener(){              
113.               @Override             
114.               public boolean onError(MediaPlayer arg0, int arg1, int arg2){                
115.                   // TODO Auto-generated method stub                
116.                   try{                  
117.                       //發生錯誤時,釋放資源                 
118.                       mpPlayer.release();                  
119.                       tvPrompt.setText("播放發生異常!");                
120.                   }                
121.                   catch (Exception e){                  
122.                       tvPrompt.setText(e.toString());                   
123.                       e.printStackTrace();                 
124.                   }                 
125.                   return false;               
126.               }             
127.          });           
128.     }         
129.                 
130. }  
131.           

三、運行結果

單擊“播放”按鈕，一段優美的“走過咖啡屋”歌聲從這裡就開始了。