Android MediaPlayer单例

Question

我在这里阅读了几篇建议使用单例代码的文章，我已经阅读并放入音板，因为我想使用单例代码只允许一个媒体播放器实例，无论用户定义了多少次点击.

基本上我只想要一种声音，如果用户在播放期间单击另一个按钮，它会停止当前声音并播放按下的声音。我只想要一个 MediaPlayer 实例，但不知道如何实现它。

这是我的代码的基本思想:

    package com.example.context;

    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;




    import android.app.Activity;
    import android.content.ContentValues;
    import android.content.Intent;
    import android.media.MediaPlayer;
    import android.net.Uri;
    import android.os.Bundle;
    import android.provider.MediaStore;
    import android.view.ContextMenu;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ContextMenu.ContextMenuInfo;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.Toast;

    public class main extends Activity implements OnClickListener {

    MediaPlayer player;

    int[] ressound ={R.raw.boomstick, R.raw.chainsaw, R.raw.shebitch, R.raw.byebye,
    R.raw.comegetsome, R.raw.groovy, R.raw.shoelace, R.raw.smart,   R.raw.yeahbaby};//added as needed
    int j=0;
    private static final String TAG = "MyTag";

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


     //Coding for all buttons, registers, and Listeners
        Button btn1 = (Button) findViewById(R.id.btn1);
        registerForContextMenu(btn1); 
        btn1.setOnClickListener(this);
        Button btn2 = (Button) findViewById(R.id.btn2);
        registerForContextMenu(btn2);
        btn2.setOnClickListener(this);
        Button btn3 = (Button) findViewById(R.id.btn3);
        registerForContextMenu(btn3);
        btn3.setOnClickListener(this);

    }

     //On click Handlers for multiple buttons 
        public void onClick(View v) {
        switch(v.getId()){
        case R.id.btn1:
        // action to perform on button 1
        j = 0;
        playResource();
        break;
    case R.id.btn2:
        // action to perform on button 1
        j = 1;
        playResource();
        break;
    case R.id.btn3:
        // action to perform on button 1    
        j = 2;
        playResource();
        break;

    }
         public void playResource(int j, int resource) {
    this.j = j;
    if (player != null) {
        if (player.isPlaying())
            player.stop();
        player.reset();
        //from MediaPlayer implementation (link above)
        try {
            AssetFileDescriptor afd = getResources().openRawResourceFd(resource);
            if (afd == null) return;
            player.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
            afd.close();
            player.prepare();
        } catch (IOException ex) {
            Log.d(TAG, "create failed:", ex);
            // failed: return
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "create failed:", ex);
            // failed: return
        } catch (SecurityException ex) {
            Log.d(TAG, "create failed:", ex);
            // failed: return
        }
    }
    else {
        //player is null
        //it will create new MediaPlayer instance, setDataSource and call prepare
        player = MediaPlayer.create(this, resource);
    }
    //if everything ok play file
    //in case of any error return from method before (catch)
    player.start();
}

这也是我必须更新和更改我的代码的地方，但它给我带来了传递 playresource() 函数的问题。我是不是传错了，传的应该是private吧。

Answer 1

为此您不需要单例。你在做什么是每次你想播放一个文件时调用创建方法。这是错误的，因为您已经拥有 MediaPlayer 实例。检查MediaPlayer.create implementation .我会这样做:

• 创建新方法 playResource(int j, int resource)
• 在每种情况下，我都会调用 R.id.btnX 方法 playResource(X, R.raw.Y) - X 和 Y 取决于 btn

playResource 方法示例:

private static final String TAG = "MyTag";
playResource(int j, int resource) {
    this.j = j;
    if (player != null) {
        if (player.isPlaying())
            player.stop();
        player.reset();
        //from MediaPlayer implementation (link above)
        try {
            AssetFileDescriptor afd = getResources().openRawResourceFd(resource);
            if (afd == null) return null;
            player.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
            afd.close();
            player.prepare();
        } catch (IOException ex) {
            Log.d(TAG, "create failed:", ex);
            // failed: return
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "create failed:", ex);
            // failed: return
        } catch (SecurityException ex) {
            Log.d(TAG, "create failed:", ex);
            // failed: return
        }
    }
    else {
        //player is null
        //it will create new MediaPlayer instance, setDataSource and call prepare
        player = MediaPlayer.create(this, resource);
    }
    //if everything ok play file
    //in case of any error return from method before (catch)
    player.start();
}

当你不再需要MediaPlayer时，你应该释放它。例如在 onPause() 调用中:

if (player != null) {
    player.release();
    player = null;
} 

我没有测试过，所以可能会有错误。希望对您有所帮助。