《第一行代码》 第八章：应用手机多媒体

一，使用通知

第一步，创建项目，书写布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent"><Buttonandroid:id="@+id/send_notice"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="发送通知"/>
</LinearLayout>

第二步：修改活动代码，写发起通知

public class MainActivity extends AppCompatActivity implements View.OnClickListener{@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Button sendNotice=(Button) findViewById(R.id.send_notice);sendNotice.setOnClickListener(this);}@Overridepublic void onClick(View view) {switch(view.getId()){case R.id.send_notice://接收一个字符串用于明确是哪个服务，创建一个通知管理器manager，对通知进行管理NotificationManager manager =(NotificationManager) getSystemService(NOTIFICATION_SERVICE);//高版本需要渠道,注意这里Build.VERSION_CODES.O是opq的o,不是数字0if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){NotificationChannel notificationChannel=new NotificationChannel("1","name",NotificationManager.IMPORTANCE_HIGH);//如果这里用IMPORTANCE_HIGH就需要在系统的设置里开启渠道，通知才能正常弹出if(manager!=null){manager.createNotificationChannel(notificationChannel);}}//使用Builder来创建构造器，并完成基本的参数配置Notification notification=new NotificationCompat.Builder(MainActivity.this,"1").setContentTitle("这是标题").setContentText("这是内容").setWhen(System.currentTimeMillis()).setSmallIcon(R.mipmap.ic_launcher).setLargeIcon(BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher)).build();if(manager!=null){manager.notify(1,notification);}break;default:break;}}
}

第三步，书写点击通知后的回调事件

新建NotificationActivity活动，修改对应的布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_centerInParent="true"android:textSize="24sp"android:text="文本内容"/>
</RelativeLayout>

修改活动代码：

public class MainActivity extends AppCompatActivity implements View.OnClickListener{@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Button sendNotice=(Button) findViewById(R.id.send_notice);sendNotice.setOnClickListener(this);}@Overridepublic void onClick(View view) {switch(view.getId()){case R.id.send_notice://回调事件，打开新的活动Intent intent =new Intent(this,NotificationActivity.class);PendingIntent pi=PendingIntent.getActivity(this,0,intent,0);//接收一个字符串用于明确是哪个服务，创建一个通知管理器manager，对通知进行管理NotificationManager manager =(NotificationManager) getSystemService(NOTIFICATION_SERVICE);//高版本需要渠道,注意这里Build.VERSION_CODES.O是opq的o,不是数字0if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){NotificationChannel notificationChannel=new NotificationChannel("1","name",NotificationManager.IMPORTANCE_HIGH);//如果这里用IMPORTANCE_HIGH就需要在系统的设置里开启渠道，通知才能正常弹出if(manager!=null){manager.createNotificationChannel(notificationChannel);}}//使用Builder来创建构造器，并完成基本的参数配置Notification notification=new NotificationCompat.Builder(MainActivity.this,"1").setContentTitle("这是标题").setContentText("这是内容").setWhen(System.currentTimeMillis()).setSmallIcon(R.mipmap.ic_launcher).setLargeIcon(BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher)).setContentIntent(pi).build();if(manager!=null){manager.notify(1,notification);}break;default:break;}}
}

主要是这几行代码：

//回调事件，打开新的活动
Intent intent =new Intent(this,NotificationActivity.class);
PendingIntent pi=PendingIntent.getActivity(this,0,intent,0);
//....
Notification notification=new NotificationCompat.Builder(MainActivity.this,"1").setContentIntent(pi)//这里注册回调函数.build();

第四步：关闭通知

在我们点击通知之后，需要把该通知移除掉，这个移除有两种方法。
【1】注册时声明

Notification notification=new NotificationCompat.Builder(MainActivity.this,"1").setAutoCancel(true).build();

【2】执行好回调后执行
我们点击通知是打开一个新的活动页，于是可以在新的活动页中，拿到该通知管理器，然后调用通知管理器的关闭通知，找到对应要关闭的通知就行关闭即可：

public class NotificationActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.notification_layout);NotificationManager manager=(NotificationManager) getSystemService(NOTIFICATION_SERVICE);manager.cancel(1);}
}

二，调用摄像头和相册

第一步：新建项目，修改布局

新建CameraAlbumTest项目，修改布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent"><Buttonandroid:id="@+id/take_photo"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="照相"/><ImageViewandroid:id="@+id/picture"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"/></LinearLayout>

第二步：修改对应的activity

public class MainActivity extends AppCompatActivity {public static final int TAKE_PHOTO=1;private ImageView picture;private Uri imageUri;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Button takePhoto =(Button) findViewById(R.id.take_photo);picture=(ImageView) findViewById(R.id.picture);takePhoto.setOnClickListener(new View.OnClickListener(){@Overridepublic void onClick(View view) {//创建file对象用于存储拍照后的图片File outputImage=new File(getExternalCacheDir(),"output_image.jpg");try {if(outputImage.exists()){outputImage.delete();}} catch (IOException e){e.printStackTrace();}if(Build.VERSION.SDK_INT>=24){imageUri= FileProvider.getUriForFile(MainActivity.this,"com.example.cameraalbumtest.fileprovider",outputImage);}else{imageUri=Uri.fromFile(outputImage);}//启动相机程序Intent intent =new Intent("android.media.action.IMAGE_CAPTURE");intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);startActivityForResult(intent,TAKE_PHOTO);}});}@Overrideprotected void onActivityResult(int requestCode, int resultCode,Intent data) {super.onActivityResult(requestCode, resultCode, 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;}}
}

第三步：在menifest文件中对内容提供器进行注册

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

其中meta-data来指定uri的共享路径，下面我们来创建它：
右击 res目录一New-Directory，创建一个xml目录，接着右击xml目录-New-File，创建一个file paths.xml文件。然后修改file paths.xml文件中的内容，如下所示:

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android"><external-pathname="my_images"path=""/>
</paths>

其中，external-path 就是用来指定 Uri 共享的name 属性的值可以随便填，path 属性的值表示共享的具体路径。这里设置空值就表示将整个 SD卡进行共享，当然你可以仅共享我们存放output imagejpg这张图片的路径
另外还有一点要注意，在Android 4.4系统之前，访问SD卡的应用关联目录也是要声明权限的，从 4.4 系统开始不再需要权限声明。那么我们为了能够兼容老版本系统的手机，还需要在AndroidManifest.xml中声明一下访问SD卡的权限：

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

实现的效果：

第四步：从相册中选择照片

修改布局，增加一个点击打开相册的按钮：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent"><Buttonandroid:id="@+id/take_photo"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="照相"/><Buttonandroid:id="@+id/choose_from_album"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="choose photos"></Button><ImageViewandroid:id="@+id/picture"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"/></LinearLayout>

1.建立点击事件及布局，进行运行时权限处理，WRITE_EXTERNAL_STORAGE为程序对SD卡的读写能力。大于6.0动态申请权限后调用openAlbum()方法，小于6.0直接调用openAlbum()方法

Button chooseFromAlbum =(Button) findViewById(R.id.choose_from_album);
chooseFromAlbum.setOnClickListener(new View.OnClickListener(){@Overridepublic 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();}}
});

2.openAlbum中构建Intent对象，指定action为android.intent.action.GET_CONTENT，为Intent设定必要参数，调用startActivityForResult来打开相册程序选择照片，其中第二个参数为CHOOSE_PHOTO的2

 private void openAlbum() {Intent intent01 = new Intent("android.intent.action.GET_CONTENT");intent01.setType("image/*");startActivityForResult(intent01, CHOOSE_PHOTO);
}

3.这样在onActivityResult中进入CHOOSE_PHOTO进行处理，为了兼容新旧版本，4.4以上调handleImageOnKitKat方法; 4.4以下调handleImageBeforeKitKat方法。因为4.4以后选择相册中的照片不在返回真实的Uri，因此需要解析。

 case CHOOSE_PHOTO:if (resultCode == RESULT_OK) {if (Build.VERSION.SDK_INT >= 19) {handleImageOnKitKat(data);} else {handleImageBeforeKitKat(data);}}

4.1.handleImageOnKitKat解析了封装的Uri,(1)如果是document类型的Uri，则通过document id处理。若URi的authority是media格式，还需要进一步的解析，通过字符串分割获得真实ID,用ID构建新Uri和判断语句，将其传至getImagePath方法中。可以获取真实路径了（2）如果是content类型的uri，则使用普通方法去处理(3)如果是File类型的uri,直接获取图片路径即可,最后调用displayImage根据图片路径显示图片。
​ 4.2.handleImageBeforeKitKat方法中Uri未经封装，无需解析，直接getIamgePath获取真实路径，再调用displayImage方法显示于界面。

@TargetApi(19)private void handleImageOnKitKat (Intent data){String imagePath = null;Uri uri = data.getData();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idString selection = MediaStore.Images.Media._ID + "=" + id;imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);} else ("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())) {imagePath = getImagePath(uri,null);}else if("file".equalsIgnoreCase(uri.getScheme())) {imagePath=uri.getPath();}displayImage(imagePath);//根据图片路径显示图片}private void handleImageBeforeKitKat(Intent data) {Uri uri = data.getData();String imagePath = getImagePath(uri,null);displayImage(imagePath);}

对应的displayImage方法：

    @SuppressLint("Range")private String getImagePath(Uri uri, String selection) {String path = null;//通过Uri和Selection来获取真是的路径图片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) {if (Build.VERSION.SDK_INT >= 29) {picture.setImageURI(getImageContentUri(MainActivity.this, imagePath));} else {Bitmap bitmap = BitmapFactory.decodeFile(imagePath);picture.setImageBitmap(bitmap);}} else {Toast.makeText(this, "failed to get image", Toast.LENGTH_SHORT).show();}}/*** 将图片转换成Uri* @param context   传入上下文参数* @param path      图片的路径* @return      返回的就是一个Uri对象*/public static Uri getImageContentUri(Context context, String path) {Cursor cursor = context.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,new String[] { MediaStore.Images.Media._ID }, MediaStore.Images.Media.DATA + "=? ",new String[] { path }, null);if (cursor != null && cursor.moveToFirst()) {int id = cursor.getInt(cursor.getColumnIndex(MediaStore.MediaColumns._ID));Uri baseUri = Uri.parse("content://media/external/images/media");return Uri.withAppendedPath(baseUri, "" + id);} else {// 如果图片不在手机的共享图片数据库，就先把它插入。if (new File(path).exists()) {ContentValues values = new ContentValues();values.put(MediaStore.Images.Media.DATA, path);return context.getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);} else {return null;}}}

总体的所有代码：

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;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Button takePhoto =(Button) findViewById(R.id.take_photo);picture=(ImageView) findViewById(R.id.picture);Button chooseFromAlbum =(Button) findViewById(R.id.choose_from_album);chooseFromAlbum.setOnClickListener(new View.OnClickListener(){@Overridepublic 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();}}});takePhoto.setOnClickListener(new View.OnClickListener(){@Overridepublic void onClick(View view) {//创建file对象用于存储拍照后的图片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.cameraalbumtest.fileprovider",outputImage);}else{imageUri= Uri.fromFile(outputImage);}//启动相机程序Intent intent =new Intent("android.media.action.IMAGE_CAPTURE");intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);startActivityForResult(intent,TAKE_PHOTO);}});}private void openAlbum() {Intent intent01 = new Intent("android.intent.action.GET_CONTENT");intent01.setType("image/*");startActivityForResult(intent01, CHOOSE_PHOTO);}@Overrideprotected void onActivityResult(int requestCode, int resultCode,Intent data) {super.onActivityResult(requestCode, resultCode, 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) {handleImageOnKitKat(data);} else {Toast.makeText(this, "2", Toast.LENGTH_SHORT).show();handleImageBeforeKitKat(data);}}break;default:break;}}@TargetApi(19)private void handleImageOnKitKat (Intent data){String imagePath = null;Uri uri = data.getData();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idString 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())) {imagePath = getImagePath(uri,null);}else if("file".equalsIgnoreCase(uri.getScheme())) {imagePath=uri.getPath();}displayImage(imagePath);//根据图片路径显示图片}private void handleImageBeforeKitKat(Intent data) {Uri uri = data.getData();String imagePath = getImagePath(uri,null);displayImage(imagePath);}@SuppressLint("Range")private String getImagePath(Uri uri, String selection) {String path = null;//通过Uri和Selection来获取真是的路径图片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) {if (Build.VERSION.SDK_INT >= 29) {picture.setImageURI(getImageContentUri(MainActivity.this, imagePath));} else {Bitmap bitmap = BitmapFactory.decodeFile(imagePath);picture.setImageBitmap(bitmap);}} else {Toast.makeText(this, "failed to get image", Toast.LENGTH_SHORT).show();}}/*** 将图片转换成Uri* @param context   传入上下文参数* @param path      图片的路径* @return      返回的就是一个Uri对象*/public static Uri getImageContentUri(Context context, String path) {Cursor cursor = context.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,new String[] { MediaStore.Images.Media._ID }, MediaStore.Images.Media.DATA + "=? ",new String[] { path }, null);if (cursor != null && cursor.moveToFirst()) {int id = cursor.getInt(cursor.getColumnIndex(MediaStore.MediaColumns._ID));Uri baseUri = Uri.parse("content://media/external/images/media");return Uri.withAppendedPath(baseUri, "" + id);} else {// 如果图片不在手机的共享图片数据库，就先把它插入。if (new File(path).exists()) {ContentValues values = new ContentValues();values.put(MediaStore.Images.Media.DATA, path);return context.getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);} else {return null;}}}
}