Android实现在线播放音乐

原文地址：http://blog.csdn.net/wwj_748/article/details/20933055 在此感谢原作者

效果实现：

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;
        }
    }

}