android开发分享Android 开发（七）

音乐播放器开发

MediaPlayer 是Android 控制音频和视频文件播放类
1.创建MediaPlayer 对象 的Create方法
2.无can构造方法 -> setDataSorce -> prepare(）加载创造文件
注意访问SDK需要授予权限
当Mediaplay.stop() 资源后需要重新加载资源，使用Mediaplay.setDataSource() 方法进行加载 ，最后还需要释放资源，防止内存泄漏

• 缺点： 1.延迟低长，占有资源多 2. 不支持同时播放多个音频

package com.example.myapplication;  import android.media.MediaPlayer; import android.net.Uri; import android.os.Build; import android.os.Bundle; import android.view.View; import android.widget.ImageButton; import android.widget.Toast;  import androidx.annotation.RequiresApi; import androidx.appcompat.app.AppCompatActivity;  import java.io.File; import java.io.IOException; /**  * MediaPlay 实现简易的播放器 */ public class MainActivity extends AppCompatActivity {      private MediaPlayer mediaPlayer;            //定义MediaPlayer对象     private boolean isPause = false;        //定义是否暂停     private File file;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);           final ImageButton btn_play = (ImageButton) findViewById(R.id.btn_play); //获取“播放/暂停”按钮         final ImageButton btn_stop = (ImageButton) findViewById(R.id.btn_stop); //获取“停止”按钮         ;         file = new File("/res/raw/bird.ogg");          if (file.exists()) {             mediaPlayer = MediaPlayer.create(this, Uri.parse(file.getAbsolutePath()));         } else {             Toast.makeText(MainActivity.this, "要播放的音频文件不存在！", Toast.LENGTH_SHORT).show();             return;         }          // 为MediaPlayer 添加监听事件 完成事件监听器，当media.play.stop 后在重新play         mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {              @Override             public void onCompletion(MediaPlayer mediaPlayer) {                 play();             }         });          btn_play.setOnClickListener(new View.OnClickListener(){              @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)             @Override             public void onClick(View view) {                 if(mediaPlayer.isPlaying() && !isPause){                     mediaPlayer.pause();                     isPause = true; // 暂停播放                     // 更好播放图标                     ((ImageButton) view).setImageDrawable(getResources().getDrawable(R.drawable.play, null));                 }else{                     mediaPlayer.start();                           //继续播放                     // 更换为暂停图标                     ((ImageButton) view).setImageDrawable(getResources().getDrawable(R.drawable.pause, null));                     isPause = false;                         //设置为播放状态                 }           }         });         btn_stop.setOnClickListener(new View.OnClickListener() { //单击停止按钮，实现停止播放音频             @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)             @Override             public void onClick(View v) {                 mediaPlayer.stop();                    //停止播放                 //更换为播放图标                 btn_play.setImageDrawable(getResources().getDrawable(R.drawable.play, null));             }         });     }      private void play(){         // 重置MediaPlay         mediaPlayer.reset();         try {             mediaPlayer.setDataSource(file.getAbsolutePath());             mediaPlayer.prepare(); // 预加载         } catch (IOException e) {             e.printStackTrace();         }     }      @Override     protected void onDestroy() {         if(mediaPlayer.isPlaying()){             mediaPlayer.stop();         }         mediaPlayer.release();         super.onDestroy();     } }  

SoundPool 播放多个音频

优点： 1. 延迟低 2.占有资源少 3. 支持多个音频播放
缺点： 不能播放大文件音频
应用场景： 小型游戏中多个飞机被击破声音
创建SoundPool 对象，load ， play

package com.example.myapplication;  import android.media.AudioAttributes; import android.media.SoundPool; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.ListView;  import androidx.appcompat.app.AppCompatActivity;  import java.util.HashMap;  public class MainActivity extends AppCompatActivity {       @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          ListView listView = findViewById(R.id.listView);          // 创建SoundPool 对象设置音频相关特性         //1.音频对象         AudioAttributes attr = new AudioAttributes.Builder()           //设置音效相关属性                 .setUsage(AudioAttributes.USAGE_GAME)                 // 设置音效使用场景                 .setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)  // 设置音效的类型                 .build();          final SoundPool soundpool = new SoundPool.Builder()           // 创建SoundPool对象                 .setAudioAttributes(attr) // 设置音效池的属性                 .setMaxStreams(10) // 设置最多可容纳10个音频流，                 .build();         // 要播放音频保存到HashMap中         final HashMap<Integer, Integer> soundmap = new HashMap<Integer, Integer>();         soundmap.put(0, soundpool.load(this, R.raw.cuckoo, 1));         soundmap.put(1, soundpool.load(this, R.raw.chimes, 1));         soundmap.put(2, soundpool.load(this, R.raw.notify, 1));         soundmap.put(3, soundpool.load(this, R.raw.ringout, 1));         soundmap.put(4, soundpool.load(this, R.raw.bird, 1));         soundmap.put(5, soundpool.load(this, R.raw.water, 1));         soundmap.put(6, soundpool.load(this, R.raw.cock, 1));          listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {             @Override             public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {                 soundpool.play(soundmap.get(i),1,1,0,0,1);             }         });     } }  

video View 播放视频

1. 在XML中添加Videoview 组件：

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout     xmlns:android="https://schemas.android.com/apk/res/android"     xmlns:tools="https://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     tools:context=".MainActivity">      <VideoView         android:id="@+id/video"         android:layout_width="match_parent"         android:layout_height="match_parent" /> </RelativeLayout>  

读取SDK上数据 设置Mainifest.xml 设置访问权限，同时在Android 机器上设置权限打开

  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />     <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" /> ----------------------------------------------------------- <?xml version="1.0" encoding="utf-8"?> <manifest package="com.mingrisoft"           xmlns:android="https://schemas.android.com/apk/res/android">     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />     <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />     <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" android:screenOrientation="landscape">             <intent-filter>                 <action android:name="android.intent.action.MAIN"/>                  <category android:name="android.intent.category.LAUNCHER"/>             </intent-filter>         </activity>     </application>  </manifest>   

package com.example.myapplication;  import android.media.MediaPlayer; import android.os.Bundle;  import com.google.android.material.floatingactionbutton.FloatingActionButton; import com.google.android.material.snackbar.Snackbar;  import androidx.appcompat.app.AppCompatActivity; import androidx.appcompat.widget.Toolbar;  import android.os.Environment; import android.view.View; import android.view.Menu; import android.view.MenuItem; import android.widget.MediaController; import android.widget.Toast; import android.widget.VideoView;  import java.io.File;  public class MainActivity extends AppCompatActivity {      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);                  VideoView videoView = findViewById(R.id.video);                  File file = new File(Environment.getExternalStorageDirectory()+"/video.mp4");         if(file.exists()){             videoView.setVideoPath(file.getAbsolutePath());         }else{             return ;         }                  // 控制视频播放         MediaController mc = new MediaController(MainActivity.this);         videoView.setMediaController(mc);         // videoiew 获取焦点         videoView.requestFocus();         videoView.start();                  // 完成监听器         videoView.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {             @Override             public void onCompletion(MediaPlayer mediaPlayer) {                 Toast.makeText(MainActivity.this,"视频播放完成",Toast.LENGTH_SHORT).show();             }         });     }  } 

控制摄像头摄像

 <!-- 授予程序可以向SD卡中保存文件的权限 -->     <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>     <!-- 授予程序使用摄像头的权限 -->     <uses-permission android:name="android.permission.CAMERA"/>     <uses-feature android:name="android.hardware.camera.autofocus"/>     <uses-feature android:name="android.hardware.camera"/> 

package com.example.myapplication;   import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.PixelFormat; import android.hardware.Camera; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.provider.MediaStore; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.view.WindowManager; import android.widget.ImageButton; import android.widget.Toast;  import androidx.appcompat.app.AppCompatActivity;  import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException;  public class MainActivity extends AppCompatActivity {      private Camera camera;     private boolean isPreview = false; // 设置是否是预览状态      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          //设置全屏显示         getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,                 WindowManager.LayoutParams.FLAG_FULLSCREEN);          if (!android.os.Environment.getExternalStorageState().equals(  //判断手机是否安装SD卡                 android.os.Environment.MEDIA_MOUNTED)) {             Toast.makeText(this, "请安装SD卡！", Toast.LENGTH_SHORT).show(); // 提示安装SD卡         }         // 设置预览         final SurfaceView surfaceView = findViewById(R.id.surfaceView);          final SurfaceHolder surfaceHolder = surfaceView.getHolder();         // 设置自己维护缓存         surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);         ImageButton preview = (ImageButton) findViewById(R.id.preview);        //获取“预览”按钮         ImageButton takePicture = (ImageButton) findViewById(R.id.takephoto);  //获取“拍照”按钮          preview.setOnClickListener(new View.OnClickListener() {             @Override             public void onClick(View view) {                  if (!isPreview) {                     camera = Camera.open();                     isPreview = true;                 }                  try {                     camera.setPreviewDisplay(surfaceHolder);                   // 设置用于显示预览的SurfaceView                     Camera.Parameters parameters = camera.getParameters();    //获取相机参数                     parameters.setPictureFormat(PixelFormat.JPEG);    //指定图片为JPEG图片                     parameters.set("jpeg-quality", 80);            //设置图片的质量                     camera.setParameters(parameters);                //重新设置相机参数                     camera.startPreview();                            //开始预览                     camera.autoFocus(null);                        //设置自动对焦                 } catch (IOException e) {                           //输出异常信息                     e.printStackTrace();                 }             }         });          // 保存拍照          //实现相机拍照功能         takePicture.setOnClickListener(new View.OnClickListener() {             @Override             public void onClick(View v) {                 if (camera != null) {                                     //相机不为空                     camera.takePicture(null, null, jpeg);                //进行拍照                 }             }         });      }      final   Camera.PictureCallback jpeg = new Camera.PictureCallback() {         @Override         public void onPictureTaken(byte[] data, Camera camera) {             // 根据拍照所得的数据创建位图             final Bitmap bm = BitmapFactory.decodeByteArray(data, 0,                     data.length);             camera.stopPreview();        //停止预览             isPreview = false;         //设置为非预览状态             //获取sd卡根目录             File appDir = new File(Environment.getExternalStorageDirectory(), "/DCIM/Camera/");             if (!appDir.exists()) {      //如果该目录不存在                 appDir.mkdir();          //就创建该目录              }             String fileName = System.currentTimeMillis() + ".jpg"; //将获取当前系统时间设置为照片名称             File file = new File(appDir, fileName);  //创建文件对象              try {  //保存拍到的图片                 FileOutputStream fos = new FileOutputStream(file);  //创建一个文件输出流对象                 bm.compress(Bitmap.CompressFormat.JPEG, 100, fos);  //将图片内容压缩为JPEG格式输出到输出流对象中                 fos.flush();                                        //将缓冲区中的数据全部写出到输出流中                 fos.close();                                        //关闭文件输出流对象             } catch (FileNotFoundException e) {                 e.printStackTrace();             } catch (IOException e) {                 e.printStackTrace();             }             // 将照片插入到图库当中              try {                 MediaStore.Images.Media.insertImage(MainActivity.this.getContentResolver(),                         file.getAbsolutePath(),fileName,null);             } catch (FileNotFoundException e) {                 e.printStackTrace();             }              // 更新通知图库             MainActivity.this.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + "")));              restCamera();         }     };      private void restCamera(){         if(!isPreview){             camera.startPreview();             isPreview = true;          }     }       @Override     protected void onPause() {  //当暂停Activity时，停止预览并释放资源         if (camera != null) {        //如果相机不为空             camera.stopPreview();    //停止预览             camera.release();        //释放资源         }         super.onPause();     } }