app播放app工程自帶（不是SD卡里的）的音樂檔案。

1.在工程res資料夾裡新建raw資料夾，在raw資料夾裡放置一份mp3檔案。

2.在MainActivity.java檔案裡

public class MainActivity extends Activity下面一行

 private MediaPlayer mp=new MediaPlayer();

MediaPlayer mp =MediaPlayer.create(this, R.raw.music);
mp.start();

xml檔案內容如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MainActivity"
    android:orientation="horizontal">
    <Button
        android:id="@+id/play"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="4"
        android:text="播放"/>
</LinearLayout>
 

package com.example.testmusic;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity
{
    private MediaPlayer mp=new MediaPlayer();
    private Button play;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        play=(Button) findViewById(R.id.play);
        final MediaPlayer mp =MediaPlayer.create(this, R.raw.music);
        play.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mp.start();
            }
        });
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mp != null) {
            mp.stop();
            mp.release();
        }
    }
}