广播应用不在后台运行

Question

我有无线电应用程序，可以播放在线广播。但它不适用于背景，即当我按下主页按钮手机时会自动将其关闭。我如何让它在背景上运行。

package com.radioawaz.simerpreetjassal.radioawaz;

import android.app.Activity;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnBufferingUpdateListener;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;

import java.io.IOException;

public class MainActivity extends Activity implements OnClickListener {

    private ProgressBar playSeekBar;

    private Button buttonPlay;

    private Button buttonStopPlay;

    private MediaPlayer player;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initializeUIElements();

        initializeMediaPlayer();
    }

    private void initializeUIElements() {

        playSeekBar = (ProgressBar) findViewById(R.id.progressBar1);
        playSeekBar.setMax(100);
        playSeekBar.setVisibility(View.INVISIBLE);

        buttonPlay = (Button) findViewById(R.id.buttonPlay);
        buttonPlay.setOnClickListener(this);

        buttonStopPlay = (Button) findViewById(R.id.buttonStopPlay);
        buttonStopPlay.setEnabled(false);
        buttonStopPlay.setOnClickListener(this);

    }

    public void onClick(View v) {
        if (v == buttonPlay) {
            startPlaying();
        } else if (v == buttonStopPlay) {
            stopPlaying();
        }
    }

    private void startPlaying() {
        buttonStopPlay.setEnabled(true);
        buttonPlay.setEnabled(false);

        playSeekBar.setVisibility(View.VISIBLE);

        player.prepareAsync();

        player.setOnPreparedListener(new OnPreparedListener() {

            public void onPrepared(MediaPlayer mp) {
                Log.e("ready!","ready");
                player.start();
            }
        });

    }

    private void stopPlaying() {
        if (player.isPlaying()) {
            player.stop();
            player.release();
            initializeMediaPlayer();
        }

        buttonPlay.setEnabled(true);
        buttonStopPlay.setEnabled(false);
        playSeekBar.setVisibility(View.INVISIBLE);
    }

    private void initializeMediaPlayer() {
        player = new MediaPlayer();
        try {
            player.setDataSource("http://streaming.shoutcast.com/Radioawazca?lang=en-ca");
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        player.setOnBufferingUpdateListener(new OnBufferingUpdateListener() {

            public void onBufferingUpdate(MediaPlayer mp, int percent) {
                playSeekBar.setSecondaryProgress(percent);
                Log.i("Buffering", "" + percent);
            }
        });
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (player.isPlaying()) {
            player.stop();
        }
    }
}

以上都是我的主要活动。请看，并提出建议。谢谢。