java - Android Studio 中基本音乐播放器中的音频问题

Question

我在 Android Studio 中创建了一个基本的音乐播放器应用程序，音乐文件存储在资源下的 raw 目录中，格式为 Mp3。问题是，虽然事件监听器内的 toast 被显示，但音频只播放一次(我真的不知道如何)。代码如下。

list 文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.basicmusicplayer">

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"

        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

xml 文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_gravity="center"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/greetings"
        android:textSize="30sp"
        android:textStyle="bold"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="221dp"
        android:layout_height="298dp"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="104dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.505"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        app:srcCompat="@android:drawable/ic_media_play" />

    <Button
        android:id="@+id/pause"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="8dp"
        android:text="@string/pause"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/stop"
        app:layout_constraintHorizontal_bias="0.565"
        app:layout_constraintStart_toEndOf="@+id/play"
        app:layout_constraintTop_toBottomOf="@+id/imageView"
        app:layout_constraintVertical_bias="0.205" />

    <Button
        android:id="@+id/play"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:text="@string/play"
        app:layout_constraintBaseline_toBaselineOf="@+id/pause"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/stop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:text="@string/stop"
        app:layout_constraintBaseline_toBaselineOf="@+id/pause"
        app:layout_constraintEnd_toEndOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

java代码

package com.example.basicmusicplayer;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity {
    MediaPlayer player;

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

        /*
         an object of class MediaPlayer created named player
         a mp3 file is added to the object using create method*/
        player = MediaPlayer.create(this, R.raw.adele);

//        setting up  inline event listeners to the button
//        first comes the play button
        Button play_music = findViewById(R.id.play);
        play_music.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "Playing sound",Toast.LENGTH_SHORT).show();
                player.start();

            }
        });

//        adding event listener on pause button
        Button pause_music = findViewById(R.id.pause);
        pause_music.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "paused sound",Toast.LENGTH_SHORT).show();
                player.pause();

            }
        });

//        adding event listener for stop button
        Button stop_music = findViewById(R.id.stop);
        stop_music.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "stopped sound",Toast.LENGTH_SHORT).show();
                player.stop();

            }
        });



    }
}

Answer 1

 private MediaPlayer mp;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button b = (Button) findViewById(R.id.button1);

        final TextView t = (TextView) findViewById(R.id.textView1);

        b.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                stopPlaying();
                mp = MediaPlayer.create(PlayaudioActivity.this, R.raw.far);
                mp.start();
            }

        });
    }

    private void stopPlaying() {
        if (mp != null) {
            mp.stop();
            mp.release();
            mp = null;
       }
    }