Android 音乐播放MediaPlayer

Andorid多媒体播放中的音乐播放一般是使用MediaPlayer实现的，他对音频文件提供了非常全面的方法。
梳理一下MediaPlayer工作流程,创建出一个Media对象之后用setDataSource()来设置音频文件的路径，再调用Prepare()方法使它进入到工作状态，接下来调用start()即可.

demo如下:

1：在清淡文件中添加sd卡权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

2：布局文件

就写三个按钮，开始播放，暂停播放和重新播放即可

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/play"
        android:text="play"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/pause"
        android:text="pause"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/replay"
        android:text="replay"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

3：Activity

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.content.pm.PackageManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {
    private Button play;
    private Button pause;
    private Button replay;
    private MediaPlayer mediaPlayer = new MediaPlayer();                
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        play = findViewById(R.id.play);
        pause = findViewById(R.id.pause);
        replay = findViewById(R.id.replay);

        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(MainActivity.this,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
        }else {
            try {                               //权限申请
                initMediaPlayer();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }


        play.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (!mediaPlayer.isPlaying()){
                    mediaPlayer.start();
                }
            }
        });

        pause.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (mediaPlayer.isPlaying()){
                    mediaPlayer.pause();
                }
            }
        });

        replay.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (mediaPlayer.isPlaying()){
                    mediaPlayer.reset();
                    try {
                        initMediaPlayer();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });





    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode){
            case 1:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    try {
                        initMediaPlayer();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }else {
                    Toast.makeText(MainActivity.this,"权限被拒绝",Toast.LENGTH_LONG).show();
                }
                break;
                default:
        }
    }

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

    private void initMediaPlayer() throws IOException {
        File file = new File(Environment.getExternalStorageDirectory(),"成磊 - 你不知道的事.mp3");      //这个文件要放在sd卡的根目录下
        mediaPlayer.setDataSource(file.getPath());
        mediaPlayer.prepare();
    }

}

音频文件要放在sd卡的根目录下或自定义文件路径