首先，說明我們是從sd卡里讀檔案，來播放檔案！！

1、效果圖：

提前工作，往sd卡里放音樂檔案，如圖：

2、佈局檔案main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
	<TextView 
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="歌曲名："/>
	<TextView 
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="blueflawer.mp3"/>
	<Button 
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="播放"
	    android:id="@+id/play_pause"/>
	<Button 
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="重置"
	    android:id="@+id/reset"/>
	<SeekBar 
	    android:layout_width="fill_parent"
	    android:layout_height="wrap_content"
	    android:id="@+id/seekbar"/>
</LinearLayout>
 

package cn.csdn.activity;

import java.io.File;
import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;

public class MyPlayerActivity extends Activity {
	private Button play_pause, reset;
	private SeekBar seekbar;
	private boolean ifplay = false;
	private MediaPlayer player = null;
	private String musicName = "blueflawer.mp3";
	private boolean iffirst = false;
	private Timer mTimer;  
	private TimerTask mTimerTask; 
	private boolean isChanging=false;//互斥變數，防止定時器與SeekBar拖動時進度衝突 
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		player = new MediaPlayer();
		findViews();// 各元件
	}

	private void findViews() {
		play_pause = (Button) findViewById(R.id.play_pause);
		reset = (Button) findViewById(R.id.reset);
		play_pause.setOnClickListener(new MyClick());
		reset.setOnClickListener(new MyClick());

		seekbar = (SeekBar) findViewById(R.id.seekbar);
		seekbar.setOnSeekBarChangeListener(new MySeekbar());
	}

	class MyClick implements OnClickListener {
		public void onClick(View v) {
			File file = new File(Environment.getExternalStorageDirectory(),
					musicName);
			// 判斷有沒有要播放的檔案
			if (file.exists()) {
				switch (v.getId()) {
				case R.id.play_pause:
					if (player != null && !ifplay) {
						play_pause.setText("暫停");
						if (!iffirst) {
							player.reset();
							try {
								player.setDataSource(file.getAbsolutePath());
								player.prepare();// 準備

							} catch (IllegalArgumentException e) {
								e.printStackTrace();
							} catch (IllegalStateException e) {
								e.printStackTrace();
							} catch (IOException e) {
								e.printStackTrace();
							}
							seekbar.setMax(player.getDuration());//設定進度條
							//----------定時器記錄播放進度---------//  
					        mTimer = new Timer();  
					        mTimerTask = new TimerTask() {  
					            @Override  
					            public void run() {   
					                if(isChanging==true) { 
					                    return;  
					                }
					                seekbar.setProgress(player.getCurrentPosition());
					            }  
					        }; 
					        mTimer.schedule(mTimerTask, 0, 10); 
							iffirst=true;
						}
						player.start();// 開始
						ifplay = true;
					} else if (ifplay) {
						play_pause.setText("繼續");
						player.pause();
						ifplay = false;
					}
					break;
				case R.id.reset:
					if (ifplay) {
						player.seekTo(0);
					} else {
						player.reset();
						try {
							player.setDataSource(file.getAbsolutePath());
							player.prepare();// 準備
							player.start();// 開始
						} catch (IllegalArgumentException e) {
							e.printStackTrace();
						} catch (IllegalStateException e) {
							e.printStackTrace();
						} catch (IOException e) {
							e.printStackTrace();
						}
					}
					break;
				}
			}
		}
	}
	//進度條處理
	class MySeekbar implements OnSeekBarChangeListener {
		public void onProgressChanged(SeekBar seekBar, int progress,
				boolean fromUser) {
		}

		public void onStartTrackingTouch(SeekBar seekBar) {
			isChanging=true;  
		}

		public void onStopTrackingTouch(SeekBar seekBar) {
			player.seekTo(seekbar.getProgress());
			isChanging=false;  
		}

	}
	//來電處理
	protected void onDestroy() {
		if(player != null){
			if(player.isPlaying()){
				player.stop();
			}
			player.release();
		}
		super.onDestroy();
	}

	protected void onPause() {
		if(player != null){
			if(player.isPlaying()){
				player.pause();
			}
		}
		super.onPause();
	}

	protected void onResume() {
		if(player != null){
			if(!player.isPlaying()){
				player.start();
			}
		}
		super.onResume();
	}

}