43.2. VideoView 開發

43.2. VideoView 開發
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VideoView，用於播放一段視頻媒體，它繼承了SurfaceView，位於"android.widget.VideoView"，是一個視頻控件。

		
VideoView也為開發人員提供了對應的方法，這裡簡單介紹一些常用的：

int getCurrentPosition()：獲取當前播放的位置。
int getDuration()：獲取當前播放視頻的總長度。
isPlaying()：當前VideoView是否在播放視頻。
void pause()：暫停
void seekTo(int msec)：從第幾毫秒開始播放。
void resume()：重新播放。
void setVideoPath(String path)：以檔案路徑的方式設置VideoView播放的視頻源。
void setVideoURI(Uri uri)：以Uri的方式設置VideoView播放的視頻源，可以是網絡Uri或本地Uri。
void start()：開始播放。
void stopPlayback()：停止播放。
setMediaController(MediaController controller)：設置MediaController控製器。
setOnCompletionListener(MediaPlayer.onCompletionListener l)：監聽播放完成的事件。
setOnErrorListener(MediaPlayer.OnErrorListener l)：監聽播放發生錯誤時候的事件。
setOnPreparedListener(MediaPlayer.OnPreparedListener l)：：監聽視頻裝載完成的事件。

上面的一些方法通過方法名就可以瞭解用途。和MediaPlayer配合SurfaceView播放視頻不同，VideoView播放之前無需編碼裝載視頻，它會在start()開始播放的時候自動裝載視頻。並且VideoView在使用完之後，無需編碼回收資源。

43.2.1. 播放網絡視頻

加入 android.permission.INTERNET 允許訪問網絡

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

    <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>
        <activity android:name=".VideoViewActivity"></activity>
    </application>

</manifest>

最簡潔的佈局，只有一個 VideoView

			
<?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=".VideoViewActivity">

    <VideoView
        android:id="@+id/videoView"
        android:layout_width="match_parent"
        android:layout_height="236dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

播放的檔案來自 IPFS 星際檔案系統

			
package cn.netkiller.video;

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.MediaController;
import android.widget.VideoView;

public class VideoViewActivity extends AppCompatActivity {

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

        Uri uri = Uri.parse("http://ipfs.netkiller.cn/ipfs/QmcA1Fsrt6jGTVqAUNZBqaprMEdFaFkmkzA5s2M6mF85UC");
        VideoView videoView = (VideoView) this.findViewById(R.id.videoView);
        videoView.setMediaController(new MediaController(this));
        videoView.setVideoURI(uri);
        videoView.start();
        videoView.requestFocus();

    }
}

運行程序開始播放視頻，點擊視頻會在屏幕下方彈出 MediaController 控制條

43.2.2. MediaController 添加翻頁事件

			
package cn.netkiller.video;

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.MediaController;
import android.widget.Toast;
import android.widget.VideoView;

public class VideoViewActivity extends AppCompatActivity {

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

        final Uri uri = Uri.parse("http://ipfs.netkiller.cn/ipfs/QmcA1Fsrt6jGTVqAUNZBqaprMEdFaFkmkzA5s2M6mF85UC");
        final VideoView videoView = (VideoView) this.findViewById(R.id.videoView);
        MediaController mediaController = new MediaController(this);
        mediaController.setMediaPlayer(videoView);

        mediaController.setPrevNextListeners(
                new View.OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        Toast.makeText(VideoViewActivity.this, "下一曲", Toast.LENGTH_SHORT).show();
                        videoView.setVideoURI(Uri.parse("http://ipfs.netkiller.cn/ipfs/QmUaDftnPB7zCTwTASnSAWLiXWd1L5vNGEeU585rddfVTh"));
                    }
                },
                new View.OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        Toast.makeText(VideoViewActivity.this, "上一曲", Toast.LENGTH_SHORT).show();
                        videoView.setVideoURI(Uri.parse("http://ipfs.netkiller.cn/ipfs/QmbvKvj9X368WMtmkLYFuf59gSwLXYDLcdJuSiSHKPhTG4"));
                    }
                });

        videoView.setMediaController(mediaController);
        videoView.setVideoURI(uri);
        videoView.start();
        videoView.requestFocus();

    }
}

43.2.3. 靜音播放視頻

			
		videoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {

            @Override
            public void onPrepared(MediaPlayer mediaPlayer) {
                mediaPlayer.setVolume(0f, 0f);
            }
        });

43.2.4. 更新進度條

			
            new Thread() {
                @Override
                public void run() {
                    try {
                        while (videoView.isPlaying()) {
                            // 如果正在播放，沒0.5.毫秒更新一次進度條
                            int current = videoView.getCurrentPosition();
                            seekBar.setProgress(current);
                            sleep(500);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }.start();

43.2.5. 完整的例子

			
<?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=".VideoViewActivity">

    <VideoView
        android:id="@+id/videoView"
        android:layout_width="match_parent"
        android:layout_height="236dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">


        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/textViewTime"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:text="00:00" />

            <SeekBar
                android:id="@+id/seekBar"
                android:layout_width="270dp"
                android:layout_height="wrap_content" />

            <TextView
                android:id="@+id/textViewCurrentPosition"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="00:00" />
        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <Button
                android:id="@+id/buttonPlay"
                android:layout_width="183dp"
                android:layout_height="wrap_content"
                android:text="播放" />

            <Button
                android:id="@+id/buttonStop"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="停止" />

        </LinearLayout>

    </LinearLayout>

    <TextView
        android:id="@+id/textViewStatus"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:text="        "
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/videoView" />
</android.support.constraint.ConstraintLayout>

			
package cn.netkiller.video;

import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.VideoView;

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class VideoViewActivity extends AppCompatActivity implements View.OnClickListener {

    private VideoView videoView;
    private SeekBar seekBar;
    private Button buttonPlay;
    private TextView textViewTime;
    private TextView textViewCurrentPosition;
    private TextView textViewStatus;

    private Handler handler = new Handler();
    private Runnable runnable = new Runnable() {
        public void run() {
            if (videoView.isPlaying()) {
                int current = videoView.getCurrentPosition();
                seekBar.setProgress(current);
                textViewCurrentPosition.setText(time(videoView.getCurrentPosition()));
            }
            handler.postDelayed(runnable, 500);
        }
    };

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

        final Uri uri = Uri.parse("http://ipfs.netkiller.cn/ipfs/QmcA1Fsrt6jGTVqAUNZBqaprMEdFaFkmkzA5s2M6mF85UC");
        videoView = (VideoView) this.findViewById(R.id.videoView);
        videoView.setVideoURI(uri);
        videoView.requestFocus();

        videoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {

            @Override
            public void onPrepared(MediaPlayer mediaPlayer) {
                textViewTime.setText(time(videoView.getDuration()));
                textViewStatus.setText("視頻加載完畢");
                buttonPlay.setEnabled(true);

            }
        });

        // 在播放完畢被回調
        videoView.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                Toast.makeText(VideoViewActivity.this, "播放完成", Toast.LENGTH_SHORT).show();
            }
        });

        videoView.setOnErrorListener(new MediaPlayer.OnErrorListener() {

            @Override
            public boolean onError(MediaPlayer mp, int what, int extra) {
                // 發生錯誤重新播放
                play();
                Toast.makeText(VideoViewActivity.this, "播放出錯", Toast.LENGTH_SHORT).show();
                return false;
            }
        });


        textViewStatus = (TextView) findViewById(R.id.textViewStatus);
        textViewStatus.setText("玩命加載中");

        textViewTime = (TextView) findViewById(R.id.textViewTime);

        seekBar = (SeekBar) findViewById(R.id.seekBar);
        // 為進度條添加進度更改事件
        seekBar.setOnSeekBarChangeListener(onSeekBarChangeListener);

        textViewCurrentPosition = (TextView) findViewById(R.id.textViewCurrentPosition);

        buttonPlay = (Button) findViewById(R.id.buttonPlay);
        buttonPlay.setEnabled(false);
        final Button buttonStop = (Button) findViewById(R.id.buttonStop);

        buttonPlay.setOnClickListener(this);
        buttonStop.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.buttonPlay:
                play();
                break;
            case R.id.buttonStop:
                stop();
                break;
            default:
                break;
        }
    }

    private SeekBar.OnSeekBarChangeListener onSeekBarChangeListener = new SeekBar.OnSeekBarChangeListener() {
        // 當進度條停止修改的時候觸發
        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            // 取得當前進度條的刻度
            int progress = seekBar.getProgress();
            if (videoView.isPlaying()) {
                // 設置當前播放的位置
                videoView.seekTo(progress);
            }
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {

        }

        @Override
        public void onProgressChanged(SeekBar seekBar, int progress,
                                      boolean fromUser) {

        }
    };

    protected void play() {

        if (buttonPlay.getText().equals("播放")) {
            buttonPlay.setText("暫停");
            textViewStatus.setText("請您欣賞");
            // 開始綫程，更新進度條的刻度
            handler.postDelayed(runnable, 0);
            videoView.start();
            seekBar.setMax(videoView.getDuration());

        } else

        {
            buttonPlay.setText("播放");
            if (videoView.isPlaying()) {
                videoView.pause();
            }
        }

    }

    protected void stop() {
        if (videoView.isPlaying()) {
            videoView.stopPlayback();
        }
    }

    protected String time(long millionSeconds) {

        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("mm:ss");
        Calendar c = Calendar.getInstance();
        c.setTimeInMillis(millionSeconds);
        return simpleDateFormat.format(c.getTime());
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        handler.removeCallbacks(runnable);
    }

}

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第 43 章多媒體開發	起始頁	43.3. SurfaceView