项目短视频

操作示范如下（时长14：29）

【例3-4】 应用视频视图组件VideoView设计一个视频播放器

准备好视频文件sample.3gp，并将其复制到模拟器的SD卡中。

布局文件activity_video.xml的源代码

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >

    <TextView

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="视频播放器"

        android:textAlignment="center"

        android:textSize="24sp" />

    <VideoView

        android:id="@+id/video"

        android:layout_width="match_parent"

        android:layout_height="320dp" />

    <Button

        android:id="@+id/playBtn"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_marginLeft="140dp"

        android:text="播放"

        android:textSize="20sp" />

</LinearLayout>

控制文件VideoActivity.java源代码

package com.example.chap03;

import android.Manifest;

import android.app.Activity;

import android.content.pm.PackageManager;

import android.os.Bundle;

import android.os.Environment;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.MediaController;

import android.widget.VideoView;

import androidx.core.app.ActivityCompat; //与教材不同

public class VideoActivity extends Activity

{

    // Storage Permissions

    private static final int REQUEST_EXTERNAL_STORAGE = 1;

    private static String[] PERMISSIONS_STORAGE = {

            Manifest.permission.READ_EXTERNAL_STORAGE,

            Manifest.permission.WRITE_EXTERNAL_STORAGE

    };

    public static void verifyStoragePermissions(Activity activity) {

        // Check if we have write permission

        int permission =

                ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);

        if (permission != PackageManager.PERMISSION_GRANTED) {

            // We don't have permission so prompt the user

            ActivityCompat.requestPermissions(

                    activity,

                    PERMISSIONS_STORAGE,

                    REQUEST_EXTERNAL_STORAGE

            );

        }

    }

    private VideoView mVideoView;

    private Button playBtn;

    MediaController mMediaController;//对比 MediaPlayer ，自带进度条和进度控制，比MediaPlayer 更人性化

    @Override

    public void onCreate(Bundle savedInstanceState)

    {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_video);

        verifyStoragePermissions(this);//动态申请授权访问 sdcard

        //mVideoView = new VideoView(this);//调用构造器完成初始化,可略

        mVideoView = (VideoView)findViewById(R.id.video);

        mMediaController = new MediaController(this);//调用构造器完成初始化

        playBtn = (Button)findViewById(R.id.playBtn);

        playBtn.setOnClickListener(new mClick());

    }

    class mClick implements OnClickListener

    {

        @Override

        public void onClick(View v)

        {

            //String path="/sdcard/test.3gp";

            String path =

                    Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)

                            +"/sample.3gp";

            mVideoView.setVideoPath(path);

            mMediaController.setMediaPlayer(mVideoView);//关联 控制器与视频

            mVideoView.setMediaController(mMediaController);//关联 视频与控制器

            mVideoView.start();

            //playBtn.setVisibility(8);//按钮不可见，//play.setEnabled(false);

        }

    }

}

打开项目配置文件AndroidManifest.xml，修改工程要启动的Activity类名

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.chap03">

    <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=".VideoActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

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

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

</manifest>