多媒体和通知---《第一行代码Android》笔记

连接真机

从4.2版本开始，开发者选项默认是隐藏的，进入“关于手机”-“版本号”那一栏连续轻点，就能开启开发者选项。

使用通知(Notification)

当某程序希望向用户发出一些提示信息，而该程序又不在前台运行时，就可以使用通知。
发出一条通知后，手机最上方的状态栏会显示一条通知，下拉后可以看到详细内容。

基本使用方法

package com.example.notificationtest;import android.app.Notification;import android.app.NotificationManager;import android.app.PendingIntent;import android.content.Context;import android.content.Intent;import android.graphics.BitmapFactory;import android.graphics.Color;import android.net.Uri;import android.support.v4.app.NotificationCompat;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import java.io.File;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 v) {        switch (v.getId()) {            case R.id.send_notice:                Intent intent = new Intent(this, NotificationActivity.class);                /**                 * PendingIntent is one intent like Intent of delay execution.you can use getActivity(),getBroadcast() or getService() to get the object.                 *     first parameter: the context object.                 *     second parameter: less commonly,you can use 0.                 *     third parameter: Intent object.                 *     fourth parameter: make sure pendingIntent action.has four value:FLAG_ONE_SHOT/FLAG_NO_CREATE                 *         /FLAG_CANCEL_CURRENT/FLAG_UPDATE_CURRENT.                 */                PendingIntent pi = PendingIntent.getActivity(this, 0, intent, 0);                /**                 * first step,create NotificationManager object.you can use Context.getSystemService() method to get it.                 *     this method has one parameter to make sure obtain which one service,we use Context.NOTIFICATION_SERVICE here.                 */                NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);                /**                 * second step,we use one Builder constructor to abtain Notification object,but this api is often change,so we use                 *     support-v4.support-4 have one NotificationCompat class,use this class's constructor to get Notification object.                 */                Notification notification = new NotificationCompat.Builder(this)                        .setContentTitle("This is content title")                        .setContentText("This is content text")                        .setWhen(System.currentTimeMillis())                        .setSmallIcon(R.mipmap.ic_launcher)                        .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))                        //set notification onclick event.parameter is one PendingIntent object.                        .setContentIntent(pi)                        //播放声音，传入一个音频文件的uri                        .setSound(Uri.fromFile(new File("/system/media/audio/ringtones/ringtone_021.ogg")))                        //手机震动，传入的参数，下标是单数时代表静止时间，下标是双数时代表震动时间，单位毫秒                        .setVibrate(new long[]{0, 1000, 1000, 1000})                        //手机LED，（颜色，亮的时间，暗的时间）                        .setLights(Color.GREEN, 1000, 1000)                        //使用默认的显示效果，会使用系统默认的铃声、震动等效果，如果有这个，上面的声音、震动设置就无效了                        //.setDefaults(NotificationCompat.DEFAULT_ALL)                        //传入一段长文字                        .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."))                        //传入一张大图,BitmapFactory.decodeResource()是将图片解析成Bitmap对象。                        // .setStyle(new NotificationCompat.BigPictureStyle().bigPicture(BitmapFactory.decodeResource(getResources(), R.drawable.big_image)))                        /**                         * 设置通知的重要程度，5个量级：PRIORITY_DEFAULT:默认重要程度，和不设置效果一样；PRIORITY_MIN：最低的重要程度；PRIORITY_LOW：较低的重要程度；                         *     PRIORITY_HIGH:较高的重要程度；PRIORITY_MAX：最高的重要程度。                         */                        .setPriority(NotificationCompat.PRIORITY_MAX)                        //用户点击后自动取消通知                        .setAutoCancel(true)                        .build();                /**                 * third step,show the notification.                 *     first parameter:unique identification.                 *     second parameter:the notification object                 */                manager.notify(1, notification);                break;            default:                break;        }    }}

package com.example.notificationtest;import android.app.NotificationManager;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;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);        //取消通知，这里传入的parameter是创建notification是传入的unique identification        manager.cancel(1);    }}

调用摄像头和相册

package com.example.cameraalbumtest;import android.Manifest;import android.annotation.TargetApi;import android.content.ContentUris;import android.content.Intent;import android.content.pm.PackageManager;import android.database.Cursor;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.net.Uri;import android.os.Build;import android.os.Bundle;import android.os.Environment;import android.provider.DocumentsContract;import android.provider.MediaStore;import android.support.annotation.NonNull;import android.support.v4.app.ActivityCompat;import android.support.v4.content.ContextCompat;import android.support.v4.content.FileProvider;import android.support.v7.app.AppCompatActivity;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.ImageView;import android.widget.Toast;import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;public class MainActivity extends AppCompatActivity {    public static final int TAKE_PHOTO = 1;    public static final int CHOOSE_PHOTO = 2;    private ImageView picture;    private Uri imageUri;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //拍照按钮        Button takePhoto = (Button) findViewById(R.id.take_photo);        //相册中选择图片按钮        Button chooseFromAlbum = (Button) findViewById(R.id.choose_from_album);        picture = (ImageView) findViewById(R.id.picture);        //点击按钮拍照        takePhoto.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                /**                 * 创建File对象，用于存储拍照后的图片，并把图片命名为output_image.jpg，                 * 并把图片放到应用关联缓存目录下，getExternalCacheDir()函数用于获取这个目录，/sdcard/Android/data/<package name>/cache                 * 从6.0版本开始，读写sd卡被列为危险权限，图片放到其他目录需要进行运行时权限处理，而使用应用关联目录则可以调过这一步。                 */                File outputImage = new File(getExternalCacheDir(), "output_image.jpg");                try {                    if (outputImage.exists()) {                        outputImage.delete();                    }                    outputImage.createNewFile();                } catch (IOException e) {                    e.printStackTrace();                }                /**                 * 从7.0版本开始，直接使用本地真实路径的uri被认为是不安全的，会报FileUriExposedException错误。                 */                if (Build.VERSION.SDK_INT < 24) {                    imageUri = Uri.fromFile(outputImage);                } else {                    /**                     *                     * FileProvider则是一种特殊的内容提供器，它使用了和内容提供器类似的机制对数据进行保护，可以选择性得将封装过的uri共享给外部。                     * FileProvider.getUriForFile()方法将File对象转换成一个封装过的uri对象。方法有三个参数：                     *     first parameter:context object                     *     second parameter:任意唯一的字符串                     *     third parameter:刚才创建的file object                     */                    imageUri = FileProvider.getUriForFile(MainActivity.this, "com.example.cameraalbumtest.fileprovider", outputImage);                }                // 创建启动相机程序的intent                Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");                //拍摄的照片存储的路径，把uri传进入                intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);                //启动活动，返回结果会返回到onActivityResult()方法中                startActivityForResult(intent, TAKE_PHOTO);            }        });        //相册中选择照片，打开相册时需要运行时权限处理        chooseFromAlbum.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                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();                }            }        });    }    /**     * 具体打开相册操作     */    private void openAlbum() {        Intent intent = new Intent("android.intent.action.GET_CONTENT");        intent.setType("image/*");        startActivityForResult(intent, CHOOSE_PHOTO); // 打开相册    }    /**     * 相册中选照片时运行时权限处理的回调     */    @Override    public void onRequestPermissionsResult(int requestCode, String[] permissions, 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) {            //拍照的回调处理            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 (Exception e) {                        e.printStackTrace();                    }                }                break;            //相册中选择照片的回调处理            case CHOOSE_PHOTO:                if (resultCode == RESULT_OK) {                    // 判断手机系统版本号,因为从4.4版本开始，选取相册中的图片不再返回图片真实的uri了，而是一个封装过的uri，需要先解析。                    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                        handleImageBeforeKitKat(data);                    }                }                break;            default:                break;        }    }    /**     * 4.4及以上系统使用这个方法处理相册中选择的图片     * @param data     */    @TargetApi(19)    private void handleImageOnKitKat(Intent data) {        String imagePath = null;        Uri uri = data.getData();        Log.d("TAG", "handleImageOnKitKat: uri is " + uri);        //解析封装过的uri        if (DocumentsContract.isDocumentUri(this, uri)) {            // 如果是document类型的Uri，则通过document id处理            String docId = DocumentsContract.getDocumentId(uri);            if("com.android.providers.media.documents".equals(uri.getAuthority())) {                String id = docId.split(":")[1]; // 解析出数字格式的id                String selection = MediaStore.Images.Media._ID + "=" + id;                imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);            } else if ("com.android.providers.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())) {            // 如果是content类型的Uri，则使用普通方式处理            imagePath = getImagePath(uri, null);        } else if ("file".equalsIgnoreCase(uri.getScheme())) {            // 如果是file类型的Uri，直接获取图片路径即可            imagePath = uri.getPath();        }        displayImage(imagePath); // 根据图片路径显示图片    }    /**     * 4.4以下系统使用这个方法处理相册中选择的图片     * @param data     */    private void handleImageBeforeKitKat(Intent data) {        Uri uri = data.getData();        String imagePath = getImagePath(uri, null);        displayImage(imagePath);    }    /**     * 得到图片的真实路径     * @param uri     * @param selection     * @return     */    private String getImagePath(Uri uri, String selection) {        String path = null;        // 通过Uri和selection来获取真实的图片路径        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;    }    /**     * 展示图片到界面上     * @param imagePath     */    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();        }    }}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.cameraalbumtest">    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />    <application        android:allowBackup="true"        android:icon="@mipmap/ic_launcher"        android:label="@string/app_name"        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>        <!--注册内容提供器-->        <!--android:authorities 值必须与FileProvider.getUriForFile()方法中第二个参数一致-->        <provider            android:name="android.support.v4.content.FileProvider"            android:authorities="com.example.cameraalbumtest.fileprovider"            android:exported="false"            android:grantUriPermissions="true">            <!--指定uri的共享路径-->            <meta-data                android:name="android.support.FILE_PROVIDER_PATHS"                android:resource="@xml/file_paths" />        </provider>    </application></manifest>

res/xml/file_paths.xml

<?xml version="1.0" encoding="utf-8"?><paths xmlns:android="http://schemas.android.com/apk/res/android">    <!--external-path 用来指定uri共享的，name可以随便填，path表示共享的具体路径，这里设置空表示将整个sd卡进行共享-->    <external-path name="my_images" path="" /></paths>

播放音频

播放音频用MediaPlayer类。
先添加权限

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

MainActivity.java

package com.example.playaudiotest;import android.Manifest;import android.content.pm.PackageManager;import android.media.MediaPlayer;import android.os.Environment;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 java.io.File;public class MainActivity extends AppCompatActivity implements View.OnClickListener{    /**     * 播放音频的控制类     */    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);        //运行时权限        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(); // 初始化MediaPlayer        }    }    private void initMediaPlayer() {        try {            //Environment.getExternalStorageDirectory()方法获取手机内置存储卡根目录            File file = new File(Environment.getExternalStorageDirectory(), "music.mp3");            mediaPlayer.setDataSource(file.getPath()); // 指定音频文件的路径            mediaPlayer.prepare(); // 让MediaPlayer进入到准备状态        } catch (Exception e) {            e.printStackTrace();        }    }    @Override    public void onRequestPermissionsResult(int requestCode, String[] permissions, 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(); // 开始播放                }                break;            case R.id.pause:                if (mediaPlayer.isPlaying()) {                    mediaPlayer.pause(); // 暂停播放                }                break;            case R.id.stop:                if (mediaPlayer.isPlaying()) {                    mediaPlayer.reset(); // 停止播放                    initMediaPlayer();                }                break;            default:                break;        }    }    @Override    protected void onDestroy() {        super.onDestroy();        if (mediaPlayer != null) {            mediaPlayer.stop();            mediaPlayer.release();        }    }}

播放视频

播放视频用VideoView类控制。
添加权限：

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

MainActivity.java

package com.example.playvideotest;import android.Manifest;import android.content.pm.PackageManager;import android.net.Uri;import android.os.Environment;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(); // 初始化MediaPlayer        }    }    private void initVideoPath() {        File file = new File(Environment.getExternalStorageDirectory(), "movie.mp4");        videoView.setVideoPath(file.getPath()); // 指定视频文件的路径    }    @Override    public void onRequestPermissionsResult(int requestCode, String[] permissions, 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(); // 开始播放                }                break;            case R.id.pause:                if (videoView.isPlaying()) {                    videoView.pause(); // 暂停播放                }                break;            case R.id.replay:                if (videoView.isPlaying()) {                    videoView.resume(); // 重新播放                }                break;        }    }    @Override    protected void onDestroy() {        super.onDestroy();        if (videoView != null) {            videoView.suspend();        }    }}