《移动应用开发》编码实现音频的播放及暂停功能

《移动应用开发》编码实现音频的播放及暂停功能编码实现音频的播放及暂停功能。（20分）实现音频的播放和暂停功能，就要弄清MediaPlayer，本代码初始化了MediaPlayer，并对MediaPlayer设置了按钮进行播放、暂停，具体细节如下：

MediaPlayer的初始化包括读取一个MP3格式的音乐文件并设置其为循环播放：publicvoidinitMediaPlayer(){try{//Stringfile_path="/storage/0123-4567/K.Will-Melt.mp3";Stringfile_path=Environment.getExternalStorageDirectory().getAbsolutePath()+"/K.Will-Melt.mp3";//Stringfile_path="/data/K.Will-Melt.mp3";mediaPlayer.setDataSource(file_path);mediaPlayer.prepare();mediaPlayer.setLooping(true);//设置循环播放}catch(Exceptione){e.printStackTrace();}}播放/暂停功能的实现放在Play/Pause按钮中，所以需要二选一判断MediaPlayer的状态来设置音乐的播放与暂停：publicvoidplayOrPause(){flag++;if(flag>=1000)flag=2;which="pause";if(mediaPlayer.isPlaying()){mediaPlayer.pause();animator.pause();}else{mediaPlayer.start();实现进度条功能。（30分）packagegress;importandroid.app.Activity;importandroid.os.Bundle;importandroid.os.Handler;importandroid.os.Message;importandroid.widget.ProgressBar;publicclassMainActivityextendsActivity{@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);ProgressBarprogressBar=newProgressBar(this);//创建控件setContentView(progressBar);finalHandlerhandler=newHandler(){@OverridepublicvoidhandleMessage(Messagemsg){//线程内更新界面super.handleMessage(msg);progressBar.setProgress(msg.what);}};finalThreadthread=newThread(){//起一个线程@Overridepublicvoidrun(){super.run();intindex=0;intnumloop=1;while(index<100){//当小于100s时候，每秒向右滑动一次try{Thread.sleep(100);}catch(InterruptedExceptione){e.printStackTrace();}handler.sendEmptyMessage(index);index++;if(index==100){while(index>1){//当大于100s时候，每秒向左滑动一次try{Thread.sleep(100);}catch(InterruptedExceptione){e.printStackTrace();}handler.sendEmptyMessage(index);index--;}}}}};//无限循环，滑动thread.start();}}3.实现继承SQLiteOpenHelper类的dbHelper类。（50分）Android继承SQLiteOpenHelper类的DBHelper存取数据与图像如下：packagecom.test;importjava.io.ByteArrayOutputStream;importjava.io.IOException;importandroid.content.ContentValues;importandroid.content.Context;importandroid.database.Cursor;importandroid.database.sqlite.SQLiteDatabase;importandroid.database.sqlite.SQLiteOpenHelper;importandroid.graphics.Bitmap;importandroid.graphics.BitmapFactory;publicclassDBHelperextendsSQLiteOpenHelper{ privatestaticfinalStringDB_NAME="test.db"; privatestaticfinalintDB_VERSION=1; privatestaticfinalStringTABLE_NAME="info"; privatestaticfinalStringCREATE_INFO="createtableifnotexistsinfo(" +"idintegerprimarykeyautoincrement,namevarchar(20)," +"timevarchar(20),imgBLOB)"; privateSQLiteDatabasedb; DBHelper(Contextc){ // super(c,DB_NAME,null,DB_VERSION); } @Override publicvoidonCreate(SQLiteDatabasedb){ this.db=db; db.execSQL(CREATE_INFO); } publicvoidinsert(ContentValuesvalues,StringtableName){ db=getWritableDatabase(); db.insert(tableName,null,values); db.close(); } //ReturncursorwithallcolumnsbytableName publicCursorquery(StringtableName){ db=getWritableDatabase(); Cursorc=db.query(tableName,null,null,null,null,null,null); returnc; } //ReturncursorbySQLstring publicCursorrawQuery(Stringsql,String[]args){ db=getWritableDatabase(); Cursorc=db.rawQuery(sql,args); returnc; } //ExecuteasingleSQLstatement(asinsert,create,delete)insteadofaquery publicvoidexecSQL(Stringsql){ db=getWritableDatabase(); db.execSQL(sql); } //Deletebyid publicvoiddel(intid){ if(db==null) db=getWritableDatabase(); db.delete(TABLE_NAME,"id=?",newString[]{String.valueOf(id)}); } publicvoidclose(){ if(db!=null) db.close(); } @Override publicvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){ } //Bitmaptobyte[] publicbyte[]bmpToByteArray(Bitmapbmp){ //Defaultsizeis32bytes ByteArrayOutputStreambos=newByteArrayOutputStream(); try{ press(Bitmap.CompressFormat.JPEG,100,bos); bos.close(); }catch(IOExceptione){ e.printStackTrace(); } returnbos.toByteArray(); } //Cursortobitmap BitmapcursorToBmp(Cursorc,intcolumnIndex){ byte[]data=c.getBlob(columnIndex); try{ returnBitmapFactory.decodeByteArray(data,0,data.length); }catch(Exceptione){ returnnull; } }}DBhelper调用方法：//定义helperprivatestaticDBHelperhelper;//创建helperhelper=newDBHelper(this);//插入数据与图像ContentValuesvalues=newContentValues();value