android实现音乐播放器的代码和布局示例

以下是一个简单的Android音乐播放器的代码和布局示例：

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:id="@+id/player_controls"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:orientation="horizontal"
        android:padding="16dp">

        <ImageButton
            android:id="@+id/btn_previous"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_skip_previous" />

        <ImageButton
            android:id="@+id/btn_play_pause"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="16dp"
            android:layout_marginRight="16dp"
            android:src="@drawable/ic_play" />

        <ImageButton
            android:id="@+id/btn_next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_skip_next" />

        <SeekBar
            android:id="@+id/seek_bar"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:max="100"
            android:paddingLeft="16dp"
            android:paddingRight="16dp" />

        <TextView
            android:id="@+id/txt_current_time"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="00:00"
            android:textSize="12sp" />

    </LinearLayout>

    <ImageView
        android:id="@+id/cover_art"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/player_controls"
        android:scaleType="centerCrop"
        android:src="@drawable/default_cover_art" />

</RelativeLayout>

代码文件：

import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

import java.util.concurrent.TimeUnit;

public class MainActivity extends AppCompatActivity {

    private static final int UPDATE_PROGRESS = 0;
    private static final int SEEK_FORWARD_TIME = 10000;
    private static final int SEEK_BACKWARD_TIME = 10000;

    private MediaPlayer mediaPlayer;
    private Handler handler;
    private boolean isPlaying = false;

    private ImageButton btnPlayPause;
    private ImageView coverArt;
    private TextView txtCurrentTime;
    private SeekBar seekBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnPlayPause = findViewById(R.id.btn_play_pause);
        coverArt = findViewById(R.id.cover_art);
        txtCurrentTime = findViewById(R.id.txt_current_time);
        seekBar = findViewById(R.id.seek_bar);

        mediaPlayer = MediaPlayer.create(this, R.raw.sample_song);
        mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mediaPlayer) {
                stopPlayback();
            }
        });

        handler = new Handler(new Handler.Callback() {
            @Override
            public boolean handleMessage(Message message) {
                if (message.what == UPDATE_PROGRESS) {
                    updateProgress();
                }
                return false;
            }
        });

        btnPlayPause.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (isPlaying) {
                    pausePlayback();
                } else {
                    startPlayback();
                }
            }
        });

        ImageButton btnNext = findViewById(R.id.btn_next);
        btnNext.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                nextTrack();
            }
        });

        ImageButton btnPrevious = findViewById(R.id.btn_previous);
        btnPrevious.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                previousTrack();
            }
        });

        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
                if (b) {
                    mediaPlayer.seekTo(i * 1000);
                    txtCurrentTime.setText(formatTime(mediaPlayer.getCurrentPosition()));
                }
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
                handler.removeMessages(UPDATE_PROGRESS);
            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                handler.sendEmptyMessage(UPDATE_PROGRESS);
            }
        });

        updateProgress();
    }

    private void startPlayback() {
        mediaPlayer.start();
        isPlaying = true;
        btnPlayPause.setImageResource(R.drawable.ic_pause);
        updateProgress();
    }

    private void pausePlayback() {
        mediaPlayer.pause();
        isPlaying = false;
        btnPlayPause.setImageResource(R.drawable.ic_play);
        handler.removeMessages(UPDATE_PROGRESS);
    }

    private void stopPlayback() {
        mediaPlayer.stop();
        mediaPlayer.prepareAsync();
        isPlaying = false;
        btnPlayPause.setImageResource(R.drawable.ic_play);
        seekBar.setProgress(0);
        txtCurrentTime.setText(formatTime(0));
    }

    private void nextTrack() {
        // TODO: implement
    }

    private void previousTrack() {
        // TODO: implement
    }

    private void updateProgress() {
        int currentPosition = mediaPlayer.getCurrentPosition();
        int duration = mediaPlayer.getDuration();

        seekBar.setProgress(currentPosition / 1000);
        txtCurrentTime.setText(formatTime(currentPosition));

        if (currentPosition < duration) {
            handler.sendEmptyMessageDelayed(UPDATE_PROGRESS, 1000);
        }
    }

    private String formatTime(int milliseconds) {
        return String.format("%02d:%02d",
                TimeUnit.MILLISECONDS.toMinutes(milliseconds),
                TimeUnit.MILLISECONDS.toSeconds(milliseconds) -
                        TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(milliseconds))
        );
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        mediaPlayer.release();
        handler.removeCallbacksAndMessages(null);
    }
}

注意：这只是一个简单的示例，实际的音乐播放器应该实现更多的功能，如播放列表、随机播放、循环播放等。