Kotlin Android媒体播放器

MediaPlayer是用于控制音频/视频文件和流的播放的类。

android.media.MediaPlayer类用于控制音频或视频文件。它访问内置的媒体播放器服务, 例如播放音频, 视频等。要使用MediaPlayer类, 我们必须通过调用该类的create()方法来调用其创建实例。

MediaPlayer类的方法

MediaPlayer类有几种可用的方法。其中一些如下：

带有SeekBar的Android MediaPlayer示例

在此示例中, 我们将创建具有播放控制功能（如播放, 暂停和停止）的Media Player。我们还集成了SeekBar以显示媒体播放器的进度。

activity_main.xml

在activity_main.xml布局文件中, 添加“按钮”以控制媒体播放, “文本视图”显示歌曲的持续时间, “搜索栏”显示媒体文件的进度。

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
    tools:context="example.srcmini02.com.kotlinmediaplayer.MainActivity">

    <Button
        android:id="@+id/pauseBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:enabled="false"
        android:text="Pause"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/playBtn"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/playBtn"
        android:layout_width="88dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="Play"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/stopBtn"
        app:layout_constraintStart_toEndOf="@+id/pauseBtn"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/stopBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="24dp"
        android:layout_marginRight="24dp"
        android:layout_marginTop="8dp"
        android:enabled="false"
        android:text="Stop"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <RelativeLayout
        android:layout_width="368dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="76dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <TextView
            android:id="@+id/tv_pass"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        <TextView
            android:id="@+id/tv_due"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true" />

        <SeekBar
            android:id="@+id/seek_bar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/tv_pass"
            android:saveEnabled="false" />
    </RelativeLayout>
</android.support.constraint.ConstraintLayout>

MianActivity.kt

MediaPlayer类的实例是使用MediaPlayer.create()方法创建的。在此示例中, 我们从原始目录读取媒体文件。 MediaPlayer.start()方法开始播放媒体文件, MediaPlayer.pause()方法暂停媒体, 而Media.stop()方法停止播放媒体文件。

package example.srcmini02.com.kotlinmediaplayer

import android.media.MediaPlayer
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*
import android.os.Handler
import android.widget.SeekBar

class MainActivity : AppCompatActivity() {

    private lateinit var mediaPlayer: MediaPlayer
    private lateinit var runnable:Runnable
    private var handler: Handler = Handler()
    private var pause:Boolean = false
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Start the media player
        playBtn.setOnClickListener{
            if(pause){
                mediaPlayer.seekTo(mediaPlayer.currentPosition)
                mediaPlayer.start()
                pause = false
                Toast.makeText(this, "media playing", Toast.LENGTH_SHORT).show()
            }else{

                mediaPlayer = MediaPlayer.create(applicationContext, R.raw.school_bell)
                mediaPlayer.start()
                Toast.makeText(this, "media playing", Toast.LENGTH_SHORT).show()

            }
            initializeSeekBar()
            playBtn.isEnabled = false
            pauseBtn.isEnabled = true
            stopBtn.isEnabled = true

            mediaPlayer.setOnCompletionListener {
                playBtn.isEnabled = true
                pauseBtn.isEnabled = false
                stopBtn.isEnabled = false
                Toast.makeText(this, "end", Toast.LENGTH_SHORT).show()
            }
        }
        // Pause the media player
        pauseBtn.setOnClickListener {
            if(mediaPlayer.isPlaying){
                mediaPlayer.pause()
                pause = true
                playBtn.isEnabled = true
                pauseBtn.isEnabled = false
                stopBtn.isEnabled = true
                Toast.makeText(this, "media pause", Toast.LENGTH_SHORT).show()
            }
        }
        // Stop the media player
        stopBtn.setOnClickListener{
            if(mediaPlayer.isPlaying || pause.equals(true)){
                pause = false
                seek_bar.setProgress(0)
                mediaPlayer.stop()
                mediaPlayer.reset()
                mediaPlayer.release()
                handler.removeCallbacks(runnable)

                playBtn.isEnabled = true
                pauseBtn.isEnabled = false
                stopBtn.isEnabled = false
                tv_pass.text = ""
                tv_due.text = ""
                Toast.makeText(this, "media stop", Toast.LENGTH_SHORT).show()
            }
        }
        // Seek bar change listener
        seek_bar.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener {
            override fun onProgressChanged(seekBar: SeekBar, i: Int, b: Boolean) {
                if (b) {
                    mediaPlayer.seekTo(i * 1000)
                }
            }

            override fun onStartTrackingTouch(seekBar: SeekBar) {
            }

            override fun onStopTrackingTouch(seekBar: SeekBar) {
            }
        })
    }
    // Method to initialize seek bar and audio stats
    private fun initializeSeekBar() {
        seek_bar.max = mediaPlayer.seconds

        runnable = Runnable {
            seek_bar.progress = mediaPlayer.currentSeconds

            tv_pass.text = "${mediaPlayer.currentSeconds} sec"
            val diff = mediaPlayer.seconds - mediaPlayer.currentSeconds
            tv_due.text = "$diff sec"

            handler.postDelayed(runnable, 1000)
        }
        handler.postDelayed(runnable, 1000)
    }
}
// Creating an extension property to get the media player time duration in seconds
val MediaPlayer.seconds:Int
    get() {
        return this.duration / 1000
    }
// Creating an extension property to get media player current position in seconds
val MediaPlayer.currentSeconds:Int
    get() {
        return this.currentPosition/1000
    }

输出：