<Android基础> (八）手机多媒体

第八章 运用手机多媒体

8.1 将程序运行到手机上

8.2 通知

8.2.1 通知的基本用法

需要用NotificationManager来对通知进行管理，调用Context的getSystemService()方法，传入Context.NOTIFICATION_SERVICE获得。

NotificationManager manager = (NotificationManager)
getSystemService(Context.NOTIFICATION_SERVICE);

接下来要用Builder构造器来创建Notification对象，使用support-v4库中提供了一个NotificationCompat类

Notification notification = new NotificationCompat.Builder(context).build()
    .setContentTitle("This is content title")   //指定通知的标题内容
    .setContentText("This is content text")　　//指定通知的正文内容
    .setWhen(System.currentTimeMillis())　　　　//指定通知被创建的时间，以毫秒为单位
    .setSmallIcon(R.drawable.small_icon)　　　　//设置通知的小图标
    .setLargeIcon(BitmapFactory.decodeResource(getResource(),
         R.drawable.large_icon))　　　　　　　　　//设置通知的大图标
     .build();

调用notify()方法让通知显示出来，接收两个参数，第一个为id，所以确保每个通知的id都不同， 第二个参数为Notification对象，即为

manager.notify(1,notification)

1.具体实现：

新建项目NotificationTest

修改activity_main中的代码添加Button用于添加显示通知的动作

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"

    tools:context="com.example.song.notification.MainActivity">

    <Button
        android:id="@+id/send_notice"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send notice"/>
</LinearLayout>

修改MainActivity中的代码

import android.app.Notification;
import android.app.NotificationManager;
import android.graphics.BitmapFactory;
import android.support.v4.app.NotificationCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v4.app.NotificationManagerCompat;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;



public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button sendNotice = (Button)findViewById(R.id.send_notice);
        sendNotice.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch(view.getId()){
            case R.id.send_notice:
                NotificationManager manager = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
                Notification notification = new NotificationCompat.Builder(this)
                        .setContentTitle("This is content file")
                        .setContentText("This is content text")
                        .setWhen(System.currentTimeMillis())
                        .setSmallIcon(R.mipmap.ic_launcher)
                        .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
                        .build();
                manager.notify(1, notification);
                break;
            default:
                break;
        }
    }
}

运行程序：

2.PendingIntent：延迟执行的Intent

提供三个静态方法，getActivity()方法，getBroadcast()方法，getService()方法，接收参数有四个，第一个为Context，第二个参数一般用不到，传入0，第三个参数为Intent对象，第四个参数用于确定PendingIntent的行为，有FLAG_ONE_SHOT、FLAG_NO_CREATE、FLAG_CANCEL_CURRENT、FLAG_UPDATE_CURRENT四种值。

通过PendingIntent当点击通知时，跳转到其他活动

新建活动NotificationActivity

修改布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="This is notification layout"
        android:textSize="24dp"
        android:layout_gravity="center"/>

</LinearLayout>

修改MainActivity中的代码

@Override
    public void onClick(View view) {
        switch(view.getId()){
            case R.id.send_notice:
                Intent intent = new Intent(this, NotificationActivity.class);
                PendingIntent pi = PendingIntent.getActivity(this, 0, intent, 0);
                NotificationManager manager = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
                Notification notification = new NotificationCompat.Builder(this)
                        .setContentTitle("This is content file")
                        .setContentText("This is content text")
                        .setWhen(System.currentTimeMillis())
                        .setContentIntent(pi)
                        .setSmallIcon(R.mipmap.ic_launcher)
                        .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
                        .build();
                manager.notify(1, notification);
                break;
            default:
                break;
        }
    }

当点击通知时，即可跳转到NotificationActivity

但此时系统状态的通知图标仍存在，有两种方法进行取消

1）Builder连缀一个setAutoCancel方法

.setAutoCancel(true)

2）

public class NotificationActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.notification_layout);
        NotificationManager manager = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
        manager.cancel(1);
    }
}

cancel()方法中传入的1为通知的id

8.2.2 通知的进阶技巧

1.添加声音

.setSound(Uri.fromFile(new File(" ")))

2.添加振动（比如通知到来时立刻振动1秒，静止1秒，再振动1秒）

.setVibrate(new long[]{0, 1000, 1000, 1000})

同时要添加权限

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

3.控制LED灯显示（绿灯一闪一闪的效果）

   .setLights(Color.GREEN, 1000, 1000)

4.直接使用默认效果

 .setDefaults(NotificationCompat.DEFAULT_ALL)

8.2.3 通知的高级功能

1.通知内容比较短时

直接使用.setContentText

2.通知内容比较长时

 .setStyle(new NotificationCompat.BigTextStyle().bigText("Learn how to build notifications, send and sync data, and use " +
   "voice actions.Get the official Android IDE and developer tools to build apps for Android"))

3.大图片

.setStyle(new NotificationCompat.BigPictureStyle().bigPicture
(BitmapFactory.decodeResource(getResources(),R.drawable.gareen)))

4.设置重要程度

setPriority()

.setPriority(NotificationCompat.PRIORITY_MAX)

8.3 调用摄像头和相册

8.3.1 调用摄像头

新建项目CameraAlbumTest

1.修改activity_main中的代码

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.song.cameraalbumtest.MainActivity">

    <Button
        android:id="@+id/take_photo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Take Photo" />
    <ImageView
        android:id="@+id/picture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"/>
</LinearLayout>

Button用于拍照，ImageView用于将照片显示出来

2.修改MainActivity中的方法

public class MainActivity extends AppCompatActivity {

    public static final int TAKE_PHOTO = 1;

    private ImageView picture;

    private Uri imageUri;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        picture = (ImageView)findViewById(R.id.picture);
        Button takePhoto = (Button)findViewById(R.id.take_photo);
        takePhoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                File outputImage = new File(getExternalCacheDir(), "output_image.jpg");
                try{
                    if(outputImage.exists()){
                        outputImage.delete();
                    }
                    outputImage.createNewFile();
                }catch (IOException e){
                    e.printStackTrace();
                }
                if(Build.VERSION.SDK_INT >= 24){
                    imageUri = FileProvider.getUriForFile(MainActivity.this,
                            "com.example.song.cameraalbumtest.fileprovider",outputImage);
                }else{
                    imageUri = Uri.fromFile(outputImage);
                }
                Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
                intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
                startActivityForResult(intent, TAKE_PHOTO);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch(requestCode){
            case TAKE_PHOTO:
                if(resultCode == RESULT_OK){
                    try{
                        //将拍摄的照片显示出来
                        Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
                        picture.setImageBitmap(bitmap);
                    }catch(FileNotFoundException e){
                        e.printStackTrace();
                    }
                }
                break;
            default:
                break;
        }
    }
}

在AndroidManifest.xml中对内容提供器进行注册

<provider
            android:authorities="com.example.song.cameraalbumtest.fileprovider"
            android:name="android.support.v4.content.FileProvider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths"/>
</provider>

同时声明权限

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

8.3.2 从相册中选择照片

public class MainActivity extends AppCompatActivity {

    public static final int TAKE_PHOTO = 1;

    private ImageView picture;

    private Uri imageUri;

    public static final int CHOOSE_PHOTO = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        picture = (ImageView)findViewById(R.id.picture);
        Button takePhoto = (Button)findViewById(R.id.take_photo);
        Button chooseFromAlbum = (Button)findViewById(R.id.choose_from_album);
        takePhoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                File outputImage = new File(getExternalCacheDir(), "output_image.jpg");
                try{
                    if(outputImage.exists()){
                        outputImage.delete();
                    }
                    outputImage.createNewFile();
                }catch (IOException e){
                    e.printStackTrace();
                }
                if(Build.VERSION.SDK_INT >= 24){
                    imageUri = FileProvider.getUriForFile(MainActivity.this,
                            "com.example.song.cameraalbumtest.fileprovider",outputImage);
                }else{
                    imageUri = Uri.fromFile(outputImage);
                }
                Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
                intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
                startActivityForResult(intent, TAKE_PHOTO);
            }
        });
        chooseFromAlbum.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
                        != PackageManager.PERMISSION_GRANTED){
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
                }else{
                    openAlbum();
                }
            }
        });
    }
    private void openAlbum(){
        Intent intent = new Intent("android.intent.action.GET_CONTENT");
        intent.setType("image/*");
        startActivityForResult(intent, CHOOSE_PHOTO);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch(requestCode){
            case 1:
                if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    openAlbum();
                }else {
                    Toast.makeText(this, "You denied the permission", Toast.LENGTH_SHORT).show();
                }
                break;
                default:
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch(requestCode){
            case TAKE_PHOTO:
                if(resultCode == RESULT_OK){
                    try{
                        //将拍摄的照片显示出来
                        Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
                        picture.setImageBitmap(bitmap);
                    }catch(FileNotFoundException e){
                        e.printStackTrace();
                    }
                }
                break;
            case CHOOSE_PHOTO:
                if(resultCode == RESULT_OK){
                    if(Build.VERSION.SDK_INT >= 19){
                        //4.4及以上系统使用这个方法处理图片
                        handleImageOnKitkat(data);
                    }else{
                        //4.4以下系统使用这个方法处理图片
                        handleImageforeKitkat(data);
                    }
                }
                break;
            default:
                break;
        }
    }

    private void handleImageOnKitkat(Intent data){
        String imagePath = null;
        Uri uri = data.getData();
        if(DocumentsContract.isDocumentUri(this, uri)){
            String docId = DocumentsContract.getDocumentId(uri);
            if("com.android.providers.media.documents".equals(uri.getAuthority())){
                String id = docId.split(":")[1];
                String selection = MediaStore.Images.Media._ID + "=" + id;
                imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);
            }else if("com.android.provides.downloads.documents".equals(uri.getAuthority())){
                Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"),
                        Long.valueOf(docId));
                imagePath = getImagePath(contentUri, null);
            }
        }else if("content".equalsIgnoreCase(uri.getScheme())){
            imagePath = getImagePath(uri, null);
        }else if("file".equalsIgnoreCase(uri.getScheme())){
            imagePath = uri.getPath();
        }
        displayImage(imagePath);
    }

    private void handleImageforeKitkat(Intent data){
        Uri uri = data.getData();
        String imagePath = getImagePath(uri, null);
        displayImage(imagePath);
    }

    private String getImagePath(Uri uri, String selection){
        String path = null;
        Cursor cursor = getContentResolver().query(uri, null, selection, null, null);
        if(cursor != null){
            if(cursor.moveToFirst()){
                path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
            }
            cursor.close();
        }
        return path;
    }

    private void displayImage(String imagePath){
        if(imagePath != null){
            Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
            picture.setImageBitmap(bitmap);
        }else{
            Toast.makeText(this, "failed to get Image", Toast.LENGTH_SHORT).show();
        }
    }

}

 8.4 播放多媒体文件

8.4.1 播放音频

在Android中播放音频文件一般都是使用MediaPlayer类来实现的。

MediaPlayer的工作流程：首先需要创建出一个MediaPlayer对象，然后调用setDataSource()方法来设置音频文件的路径，再调用prepare()方法使MediaPlayer进入到准备状态，接下来调用start()方法就可以开始播放音频，调用pause()方法就会暂停播放，调用reset()方法就会停止播放。

新建PlayAudioTest项目，修改activity_main中的代码，放置三个按钮用于进行播放、暂停和停止操作

<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/play"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="PLAY"
         />
    <Button
        android:id="@+id/pause"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="PAUSE"
        />
    <Button
        android:id="@+id/stop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="STOP"
        />


</LinearLayout>

修改MainActivity中的代码

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private MediaPlayer mediaPlayer = new MediaPlayer();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button play = (Button)findViewById(R.id.play);
        Button pause = (Button)findViewById(R.id.pause);
        Button stop = (Button)findViewById(R.id.stop);
        play.setOnClickListener(this);
        pause.setOnClickListener(this);
        stop.setOnClickListener(this);
        if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.
                WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{
                    Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
        }else{
            initMediaPlayer();
        }
    }

    private void initMediaPlayer(){
        try{
            File file = new File(Environment.getExternalStorageDirectory(), "music.mp3");
            mediaPlayer.setDataSource(file.getPath());
            mediaPlayer.prepare();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode){
            case 1:
                if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    initMediaPlayer();
                }else{
                    Toast.makeText(this,"拒绝权限将无法使用程序",
                            Toast.LENGTH_SHORT).show();
                    finish();
                }
                break;
                default:
        }
    }

    @Override
    public void onClick(View v) {
        switch(v.getId()){
            case R.id.play:
                if(!mediaPlayer.isPlaying()){
                    mediaPlayer.start();
                }
                break;
            case R.id.pause:
                if(!mediaPlayer.isPlaying()){
                    mediaPlayer.pause();
                }
                break;
            case R.id.stop:
                if(!mediaPlayer.isPlaying()){
                    mediaPlayer.reset();
                    initMediaPlayer();
                }
                break;
            default:
                break;
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(mediaPlayer != null){
            mediaPlayer.stop();
            mediaPlayer.release();
        }
    }
}

添加权限

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

8.4.2 播放视频

新建项目PlayVideoTest

修改activity_main中的代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">

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

        <Button
            android:id="@+id/play"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Play" />
        <Button
            android:id="@+id/pause"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Pause" />

        <Button
            android:id="@+id/replay"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Stop" />
    </LinearLayout>

    <VideoView
        android:id="@+id/video_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

修改MainActivity中的代码

import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Environment;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import android.widget.VideoView;

import java.io.File;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    private VideoView videoView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        videoView = (VideoView)findViewById(R.id.video_view);
        Button play = (Button)findViewById(R.id.play);
        Button pause = (Button)findViewById(R.id.pause);
        Button replay = (Button)findViewById(R.id.replay);
        play.setOnClickListener(this);
        pause.setOnClickListener(this);
        replay.setOnClickListener(this);
        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.
                permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{
                    Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
        }else{
            initVideoPath();
        }
    }

    private void initVideoPath(){
        File file = new File(Environment.getExternalStorageDirectory(),"movie.mp4");
        videoView.setVideoPath(file.getPath());
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch(requestCode){
            case 1:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    initVideoPath();
                }else {
                    Toast.makeText(this, "拒绝权限将无法使用程序", Toast.LENGTH_SHORT).show();
                    finish();
                }
                break;
                default:
        }
    }

    @Override
    public void onClick(View v) {
        switch(v.getId()){
            case R.id.play:
                if(!videoView.isPlaying()){
                    videoView.start();
                }
                break;
            case R.id.pause:
                if(videoView.isPlaying()){
                    videoView.pause();
                }
                break;
            case R.id.replay:
                if(videoView.isPlaying()){
                    videoView.resume();
                }
                break;
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(videoView != null){
            videoView.suspend();
        }
    }
}

添加权限

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