以编程方式在android中使用文件路径播放声音文件

Question

我想通过从Android手机中选择mp3文件的路径来播放声音。 路径字符串返回mp3文件的路径但它没有播放。 这是我的代码：

import java.io.IOException;
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

    TextView textFile;

    private static final int PICKFILE_RESULT_CODE = 1;

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

        Button buttonPick = (Button) findViewById(R.id.buttonpick);
        textFile = (TextView) findViewById(R.id.textfile);

        buttonPick.setOnClickListener(new Button.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub

                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                intent.setType("audio/*");
                startActivityForResult(intent, PICKFILE_RESULT_CODE);

            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        switch (requestCode) {
        case PICKFILE_RESULT_CODE:
            if (resultCode == RESULT_OK) {

                MediaPlayer filePlayer = MediaPlayer.create(getApplicationContext(), data.getData());
                if (filePlayer != null)
                    filePlayer.start();
                else{
                    Toast.makeText(getApplicationContext(), "Empty", 1000).show();
                }
            }
            break;

        }
    }
}

有谁能告诉我这段代码有什么问题。 以及为什么mediplayer不播放我从我的存储中选择的mp3文件 这是我的堆栈跟踪

07-04 04:00:35.101: E/AndroidRuntime(17744): FATAL EXCEPTION: main
07-04 04:00:35.101: E/AndroidRuntime(17744): Process: com.example.audio, PID: 17744
07-04 04:00:35.101: E/AndroidRuntime(17744): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=content://media/external/audio/media/15787 }} to activity {com.example.audio/com.example.audio.MainActivity}: java.lang.NullPointerException
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3551)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3594)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.app.ActivityThread.access$1400(ActivityThread.java:161)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1313)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.os.Handler.dispatchMessage(Handler.java:102)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.os.Looper.loop(Looper.java:157)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.app.ActivityThread.main(ActivityThread.java:5356)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at java.lang.reflect.Method.invokeNative(Native Method)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at java.lang.reflect.Method.invoke(Method.java:515)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at dalvik.system.NativeStart.main(Native Method)
07-04 04:00:35.101: E/AndroidRuntime(17744): Caused by: java.lang.NullPointerException
07-04 04:00:35.101: E/AndroidRuntime(17744):    at com.example.audio.MainActivity.onActivityResult(MainActivity.java:53)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.app.Activity.dispatchActivityResult(Activity.java:5618)
07-04 04:00:35.101: E/AndroidRuntime(17744):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3547)
07-04 04:00:35.101: E/AndroidRuntime(17744):    ... 11 more