音乐播放器之--在线音乐播放

在线播放音乐并不难，也就是传入的Url是一个网络地址。这里我要实现一个可以进行网络缓冲的在线音乐播放。

下面介绍具体实现过程：

定义一个具有缓冲效果的播放器：Player

我们看到的缓冲效果，是通过设置拖动条SeekBar的二级进度实现的，这就要设置MediaPlayer的缓冲更新的监听了。

具体代码实现：

package com.wwj.download.util;

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

import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnBufferingUpdateListener;
import android.media.MediaPlayer.OnCompletionListener;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Handler;
import android.util.Log;
import android.widget.SeekBar;

public class Player implements OnBufferingUpdateListener, OnCompletionListener,
		OnPreparedListener {

	public MediaPlayer mediaPlayer; // 媒体播放器
	private SeekBar seekBar; // 拖动条
	private Timer mTimer = new Timer(); // 计时器

	// 初始化播放器
	public Player(SeekBar seekBar) {
		super();
		this.seekBar = seekBar;
		try {
			mediaPlayer = new MediaPlayer();
			mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);// 设置媒体流类型
			mediaPlayer.setOnBufferingUpdateListener(this);
			mediaPlayer.setOnPreparedListener(this);
		} catch (Exception e) {
			e.printStackTrace();
		}
		// 每一秒触发一次
		mTimer.schedule(timerTask, 0, 1000);
	}

	// 计时器
	TimerTask timerTask = new TimerTask() {

		@Override
		public void run() {
			if (mediaPlayer == null)
				return;
			if (mediaPlayer.isPlaying() && seekBar.isPressed() == false) {
				handler.sendEmptyMessage(0); // 发送消息
			}
		}
	};

	Handler handler = new Handler() {
		public void handleMessage(android.os.Message msg) {
			int position = mediaPlayer.getCurrentPosition();
			int duration = mediaPlayer.getDuration();
			if (duration > 0) {
				// 计算进度（获取进度条最大刻度*当前音乐播放位置 / 当前音乐时长）
				long pos = seekBar.getMax() * position / duration;
				seekBar.setProgress((int) pos);
			}
		};
	};

	public void play() {
		mediaPlayer.start();
	}

	/**
	 * 
	 * @param url
	 *            url地址
	 */
	public void playUrl(String url) {
		try {
			mediaPlayer.reset();
			mediaPlayer.setDataSource(url); // 设置数据源
			mediaPlayer.prepare(); // prepare自动播放
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (IllegalStateException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	// 暂停
	public void pause() {
		mediaPlayer.pause();
	}

	// 停止
	public void stop() {
		if (mediaPlayer != null) {
			mediaPlayer.stop();
			mediaPlayer.release();
			mediaPlayer = null;
		}
	}

	// 播放准备
	@Override
	public void onPrepared(MediaPlayer mp) {
		mp.start();
		Log.e("mediaPlayer", "onPrepared");
	}

	// 播放完成
	@Override
	public void onCompletion(MediaPlayer mp) {
		Log.e("mediaPlayer", "onCompletion");
	}

	/**
	 * 缓冲更新
	 */
	@Override
	public void onBufferingUpdate(MediaPlayer mp, int percent) {
		seekBar.setSecondaryProgress(percent);
		int currentProgress = seekBar.getMax()
				* mediaPlayer.getCurrentPosition() / mediaPlayer.getDuration();
		Log.e(currentProgress + "% play", percent + " buffer");
	}

}

package com.wwj.download;

import java.io.File;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;
import android.widget.Toast;

import com.wwj.download.util.Player;
import com.wwj.net.download.DownloadProgressListener;
import com.wwj.net.download.FileDownloader;

public class MainActivity extends Activity {
	private static final int PROCESSING = 1;
	private static final int FAILURE = -1;

	private EditText pathText; // url地址
	private TextView resultView;
	private Button downloadButton;
	private Button stopButton;
	private ProgressBar progressBar;
	private Button playBtn;
	private Player player; // 播放器
	private SeekBar musicProgress; // 音乐进度

	private Handler handler = new UIHandler();

	private final class UIHandler extends Handler {
		public void handleMessage(Message msg) {
			switch (msg.what) {
			case PROCESSING: // 更新进度
				progressBar.setProgress(msg.getData().getInt("size"));
				float num = (float) progressBar.getProgress()
						/ (float) progressBar.getMax();
				int result = (int) (num * 100); // 计算进度
				resultView.setText(result + "%");
				if (progressBar.getProgress() == progressBar.getMax()) { // 下载完成
					Toast.makeText(getApplicationContext(), R.string.success,
							Toast.LENGTH_LONG).show();
				}
				break;
			case FAILURE: // 下载失败
				Toast.makeText(getApplicationContext(), R.string.error,
						Toast.LENGTH_LONG).show();
				break;
			}
		}
	}

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		pathText = (EditText) findViewById(R.id.path);
		resultView = (TextView) findViewById(R.id.resultView);
		downloadButton = (Button) findViewById(R.id.downloadbutton);
		stopButton = (Button) findViewById(R.id.stopbutton);
		progressBar = (ProgressBar) findViewById(R.id.progressBar);
		ButtonClickListener listener = new ButtonClickListener();
		downloadButton.setOnClickListener(listener);
		stopButton.setOnClickListener(listener);
		playBtn = (Button) findViewById(R.id.btn_online_play);
		playBtn.setOnClickListener(listener);
		musicProgress = (SeekBar) findViewById(R.id.music_progress);
		player = new Player(musicProgress);
		musicProgress.setOnSeekBarChangeListener(new SeekBarChangeEvent());
	}

	private final class ButtonClickListener implements View.OnClickListener {
		@Override
		public void onClick(View v) {
			switch (v.getId()) {
			case R.id.downloadbutton: // 开始下载
				// http://abv.cn/music/光辉岁月.mp3，可以换成其他文件下载的链接
				String path = pathText.getText().toString();
				String filename = path.substring(path.lastIndexOf('/') + 1);

				try {
					// URL编码（这里是为了将中文进行URL编码）
					filename = URLEncoder.encode(filename, "UTF-8");
				} catch (UnsupportedEncodingException e) {
					e.printStackTrace();
				}

				path = path.substring(0, path.lastIndexOf("/") + 1) + filename;
				if (Environment.getExternalStorageState().equals(
						Environment.MEDIA_MOUNTED)) {
					// File savDir =
					// Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES);
					// 保存路径
					File savDir = Environment.getExternalStorageDirectory();
					download(path, savDir);
				} else {
					Toast.makeText(getApplicationContext(),
							R.string.sdcarderror, Toast.LENGTH_LONG).show();
				}
				downloadButton.setEnabled(false);
				stopButton.setEnabled(true);
				break;
			case R.id.stopbutton: // 暂停下载
				exit();
				Toast.makeText(getApplicationContext(),
						"Now thread is Stopping!!", Toast.LENGTH_LONG).show();
				downloadButton.setEnabled(true);
				stopButton.setEnabled(false);
				break;
			case R.id.btn_online_play:
				new Thread(new Runnable() {

					@Override
					public void run() {
						player.playUrl(pathText.getText().toString());
					}
				}).start();
				break;
			}
		}

		/*
		 * 由于用户的输入事件(点击button, 触摸屏幕....)是由主线程负责处理的，如果主线程处于工作状态，
		 * 此时用户产生的输入事件如果没能在5秒内得到处理，系统就会报“应用无响应”错误。
		 * 所以在主线程里不能执行一件比较耗时的工作，否则会因主线程阻塞而无法处理用户的输入事件，
		 * 导致“应用无响应”错误的出现。耗时的工作应该在子线程里执行。
		 */
		private DownloadTask task;

		private void exit() {
			if (task != null)
				task.exit();
		}

		private void download(String path, File savDir) {
			task = new DownloadTask(path, savDir);
			new Thread(task).start();
		}

		/**
		 * 
		 * UI控件画面的重绘(更新)是由主线程负责处理的，如果在子线程中更新UI控件的值，更新后的值不会重绘到屏幕上
		 * 一定要在主线程里更新UI控件的值，这样才能在屏幕上显示出来，不能在子线程中更新UI控件的值
		 * 
		 */
		private final class DownloadTask implements Runnable {
			private String path;
			private File saveDir;
			private FileDownloader loader;

			public DownloadTask(String path, File saveDir) {
				this.path = path;
				this.saveDir = saveDir;
			}

			/**
			 * 退出下载
			 */
			public void exit() {
				if (loader != null)
					loader.exit();
			}

			DownloadProgressListener downloadProgressListener = new DownloadProgressListener() {
				@Override
				public void onDownloadSize(int size) {
					Message msg = new Message();
					msg.what = PROCESSING;
					msg.getData().putInt("size", size);
					handler.sendMessage(msg);
				}
			};

			public void run() {
				try {
					// 实例化一个文件下载器
					loader = new FileDownloader(getApplicationContext(), path,
							saveDir, 3);
					// 设置进度条最大值
					progressBar.setMax(loader.getFileSize());
					loader.download(downloadProgressListener);
				} catch (Exception e) {
					e.printStackTrace();
					handler.sendMessage(handler.obtainMessage(FAILURE)); // 发送一条空消息对象
				}
			}
		}
	}

	// 进度改变
	class SeekBarChangeEvent implements OnSeekBarChangeListener {
		int progress;

		@Override
		public void onProgressChanged(SeekBar seekBar, int progress,
				boolean fromUser) {
			// 原本是(progress/seekBar.getMax())*player.mediaPlayer.getDuration()
			this.progress = progress * player.mediaPlayer.getDuration()
					/ seekBar.getMax();
		}

		@Override
		public void onStartTrackingTouch(SeekBar seekBar) {

		}

		@Override
		public void onStopTrackingTouch(SeekBar seekBar) {
			// seekTo()的参数是相对与影片时间的数字，而不是与seekBar.getMax()相对的数字
			player.mediaPlayer.seekTo(progress);
		}

	}

	@Override
	protected void onDestroy() {
		super.onDestroy();
		if (player != null) {
			player.stop();
			player = null;
		}
	}

}

源自： http://blog.csdn.net/wwj_748/article/details/20933055