本系列学习笔记第8章
前言
打算把android基本知识点写一个系列，旨在把android基础书，例如《Android 第一行代码 第2版》、《爱上android》、《疯狂android讲义》等书的一些知识点记录一下，会持续更新内容，为了方便自己复习，也希望可以帮助到大家！
1、使用通知
通知是android系统中比较有特色的一个功能，当某个应用程序希望向用户发出一些提示信息，而该应用程序又不在前台运行时，就可以借助通知来实现。发出一条通知后，手机最上方的状态栏中会显示一个通知的图标，下拉状态栏后可以看到通知的详细内容。
1.1 通知的基本用法
activity_main.xml文件
activity_notification.xml文件
NotificationActivity.java文件
public class NotificationActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_notification);
//取消通知的另外一种写法
// NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
// manager.cancel(1);
}
}
MainActivity.java文件
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnSend = (Button) findViewById(R.id.btn_send);
btnSend.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
initNotification();
}
});
}
/**
*
*/
private void initNotification() {
//设置延迟意图:跳转到下一页
Intent intent = new Intent(this,NotificationActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
//设置标题
builder.setContentTitle("美女来了");
//设置内容
builder.setContentText("美女来了美女来了美女来了");
//设置时间
builder.setWhen(System.currentTimeMillis());
//设置小图标
builder.setSmallIcon(R.mipmap.ic_launcher);
//设置大图标
builder.setLargeIcon(BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher));
//配置延迟意图
builder.setContentIntent(pendingIntent);
//自动取消
builder.setAutoCancel(true);
Notification notification = builder.build();
manager.notify(1,notification);
}
}
1.2 通知的进阶技巧
查看系统下音频文件
image.png
/**
*
*/
private void initNotification() {
//设置延迟意图:跳转到下一页
Intent intent = new Intent(this,NotificationActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
//设置标题
builder.setContentTitle("美女来了");
//设置内容
builder.setContentText("美女来了美女来了美女来了");
//设置时间
builder.setWhen(System.currentTimeMillis());
//设置小图标
builder.setSmallIcon(R.mipmap.ic_launcher);
//设置大图标
builder.setLargeIcon(BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher));
//配置延迟意图
builder.setContentIntent(pendingIntent);
//自动取消
builder.setAutoCancel(true);
//设置声音
builder.setSound(Uri.fromFile(new File("/system/media/audio/ringtones/Luna.ogg")));
//设置震动
builder.setVibrate(new long[]{0,1000,1000,1000});
//设置灯光
builder.setLights(Color.RED,1000,1000);
//默认设置
// builder.setDefaults(NotificationCompat.DEFAULT_ALL);
Notification notification = builder.build();
//注册
manager.notify(1,notification);
}
1.3 通知的高级功能
/**
*
*/
private void initNotification() {
//设置延迟意图:跳转到下一页
Intent intent = new Intent(this,NotificationActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
//设置标题
builder.setContentTitle("美女来了");
//设置内容
builder.setContentText("美女来了美女来了美女来了");
//设置时间
builder.setWhen(System.currentTimeMillis());
//设置小图标
builder.setSmallIcon(R.mipmap.ic_launcher);
//设置大图标
builder.setLargeIcon(BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher));
//配置延迟意图
builder.setContentIntent(pendingIntent);
//自动取消
builder.setAutoCancel(true);
//设置声音
builder.setSound(Uri.fromFile(new File("/system/media/audio/ringtones/Luna.ogg")));
//设置震动
builder.setVibrate(new long[]{0,1000,1000,1000});
//设置灯光
builder.setLights(Color.RED,1000,1000);
//默认设置
// builder.setDefaults(NotificationCompat.DEFAULT_ALL);
//设置长文本
// builder.setStyle(new NotificationCompat.BigTextStyle(builder).bigText("我哦哦看空的咔咔咔的口袋空空的口袋空空的看空" +
// "看多空咔咔咔咔咔咔的坎坎坷坷快快赌东道赌东道赌东" +
// "反反复复反反复复反反复复反反复复反反复复道赌东道赌东道赌东道赌东道赌东道"));
//设置大图
builder.setStyle(new NotificationCompat.BigPictureStyle(builder).bigPicture(BitmapFactory.decodeResource(getResources(),R.mipmap.timg)));
//设置优先级:默认是PRIORITY_DEFAULT
builder.setPriority(NotificationCompat.PRIORITY_MAX);
Notification notification = builder.build();
//注册
manager.notify(1,notification);
}
2、调用摄像头拍照
应用关联缓存目录：
是指SD卡中专门用于存放当前应用缓存数据的位置，调用getExternalCacheDir()方法可以得到这个目录，具体路径是/sdcard/Android/data/包名/cache 下。对这个目录进行读写操作，可以避开android6.0运行时权限处理。
file_paths.xml文件
image.png
AndroidManifest.xml文件
activity_main.xml文件
MainActivity.java文件
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);
Button takePhoto = (Button) findViewById(R.id.btn_camera);
picture = (ImageView) findViewById(R.id.iv_picture);
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
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 = Uri.fromFile(outputImage);
} else {
imageUri = FileProvider.getUriForFile(MainActivity.this, "com.example.cameraalbumdemo.fileprovider", 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);
}
});
}
@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 (Exception e) {
e.printStackTrace();
}
}
break;
default:
break;
}
}
}
image.png
3、选择相册中的照片
AndroidManifest.xml
activity_main.xml文件
MainActivity.java文件
public class MainActivity extends AppCompatActivity {
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);
Button chooseFromAlbum = (Button) findViewById(R.id.btn_picture);
picture = (ImageView) findViewById(R.id.iv_picture);
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();
}
}
});
}
private void openAlbum() {
Intent intent = new Intent("android.intent.action.GET_CONTENT");
intent.setType("image/*");
startActivityForResult(intent, CHOOSE_PHOTO); // 打开相册
}
@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) {
case CHOOSE_PHOTO:
if (resultCode == RESULT_OK) {
// 判断手机系统版本号
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;
}
}
@TargetApi(19)
private void handleImageOnKitKat(Intent data) {
String imagePath = null;
Uri uri = data.getData();
Log.d("TAG", "handleImageOnKitKat: uri is " + 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
}
private void handleImageBeforeKitKat(Intent data) {
Uri uri = data.getData();
String imagePath = getImagePath(uri, null);
displayImage(imagePath);
}
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;
}
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();
}
}
}
image.png
4、播放音频
image.png
image.png
AndroidManifest.xml文件
activity_main.xml文件
MainActivity.java文件
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(); // 初始化MediaPlayer
}
}
private void initMediaPlayer() {
try {
File file = new File(Environment.getExternalStorageDirectory(), "a.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();
}
}
}
image.png
5、播放视频
image.png
image.png
image.png
AndroidManifest.xml文件
activity_main.xml文件
MainActivity.java文件
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(), "a.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();
}
}
}
image.png