11.安卓基础之多媒体

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Android 多媒体基础知识

概述

计算机发展到今天,不仅表示数值和符号,已具有了对文本,图形,图像动画及音频视频等多种信息的综合处理能力,我们称之为多媒体技术.

图像与图形

在计算机中,
图像是采用位图形式来表示的;
图形是采用矢量图方式来表示的;

位图图像

称为光栅图或点阵图像,是由许多像小方块一样的”像素”(pixels)组成的图形.
位图图像

  • 图像 : 是由像素点阵组成的画面.
  • 位图 : 由许多点组成的点阵图.构成位图的点称为像素.
  • 色彩深度 : 位图所能达到的最大颜色数,称为色彩深度.(对于黑白两种颜色的图像来说一个像素点可用一个二进制位来表示,如0表示黑色,1表示白色.)

图片的操作

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// 1. 准备画纸:(大小和材质需要参考原图)
Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(),
        srcBitmap.getHeight(), srcBitmap.getConfig());
// 2. 准备画板，将画纸放到画板上
Canvas canvas = new Canvas(copyBitmap);
// 3. 准备画笔
Paint paint = new Paint();
// 4. 按照一定的规则
Matrix matrix = new Matrix();// 1:1照着画
// 5. 将原图像按照规则画到画板上
canvas.drawBitmap(srcBitmap, matrix, paint);

  • 图片的缩放

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    matrix.setScale(0.6f, 0.8f);

  • 图片的平移

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    matrix.setTranslate(50, 50);

位图图像的缺陷

  • 位图放大和缩小都会引起像素的增加或减少,这样会使得原由的图像的线条和形状变得参差不齐,与原图像相比出现失真;出现”锯齿形”.

位图

位图常见的文件格式

  • .bmp
  • .jpg
  • .gif
  • .png

矢量图像

矢量图形是通过计算机将一串线条和图形转换为一系列指令,在计算机中只存储这些指令,而不是像素.矢量图像看起来没有位图图像真实,但矢量图形的存储空间比位图图像要小得多,而且矢量图像通过拉伸,移动,放大等操作,图像不会产生实真.

矢量图像

颜色矩阵

1 0 0 0 0
0 1 0 0 0
0 0 1 0 0
0 0 0 1 0

颜色矩阵的代码表述

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New Red Value = 1*128 + 0*128 + 0*128 + 0*0 + 0
New Green Value = 0*128 + 1*128 + 0*128 + 0*0 + 0
New Blue Value = 0*128 + 0*128 + 1*128 + 0*0 + 0
New Alpha Value = 0*128 + 0*128 + 0*128 + 1*0 + 0
ColorMatrix cm = new ColorMatrix();
cm.set(new float[] {
2, 0, 0, 0, 0,
0, 1, 0, 0, 0,
0, 0, 1, 0, 0,
0, 0, 0, 1, 0
});
paint.setColorFilter(new ColorMatrixColorFilter(cm));

传感器

传感器(英文名称 : sensor)是一种检测装置,能感受到被测量的信息,并能将感受到的信息,按一定规律变换成为电信号或其他所需形式的信息输出,以满足信息的传输,处理,存储,显示,记录和控制等要求.

传感器的特点包括 : 微型化,数字化,智能化,多功能化,系统化,网络化.它是实现自动检测和自动控制的首要环节.传感器的存在和发展,让物体有了触觉,味觉和嗅觉等感官,让物体慢慢变得活了起来.通常根据其基本感知功能分为热敏元件,光敏元件,气敏元件,力敏元件,磁敏元件,湿敏元件,声敏元件,放射线敏感元件,色敏元件和味敏元件等十大类.

传感器

传感器类型 描述
SENSOR_TYPE_ACCELEROMETER 加速度
SENSOR_TYPE_MAGNETIC_FIELD 磁力
SENSOR_TYPE_ORIENTATION 方向
SENSOR_TYPE_GYROSCOPE 陀螺仪
SENSOR_TYPE_LIGHT 光线感应
SENSOR_TYPE_PRESSURE 压力
SENSOR_TYPE_TEMPERATURE 温度
SENSOR_TYPE_PROXIMITY 接近
SENSOR_TYPE_GRAVITY 重力
SENSOR_TYPE_LINEAR_ACCELERATION 线性加速度

练习案例

  • 加载大图片到内存

获取到读写内存权限

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

代码实现部分

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    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv =(ImageView) findViewById(R.id.iv);
    }
    public void loadBitmap(View v){
        String path = "mnt/sdcard/1.jpg";
        //通过手机的屏幕的宽高和图片的宽高来计算采样率
        //屏幕宽高
        DisplayMetrics metrics = getResources().getDisplayMetrics();
        int screenWidth = metrics.widthPixels;//获取屏幕宽度
        int screentHeight = metrics.heightPixels;//获取屏幕高度
        //图片的宽高
        try{
            ExifInterface exif = new ExifInterface(path);
            int picWidth = exif.getAttributeInt(ExifInterface.TAG_IMAGE_WIDTH,0);
            int picHeight = exif.getAttributeInt(ExifInterface.TAG_IMAGE_LENGTH,0);
            //用图片的宽度/屏幕的宽度
            int widthSample = (int)(picWidth*1f/screenWidth+0.5f);//四舍五入
            int heightSample = (int)(picHeight*1f/screentHeight+0.5f);//四舍五入
            int sample = (int) (Math.sqrt(widthSample * widthSample
                    + heightSample * heightSample) + 0.5f);
            //加载图片
            BitmapFactory.Options opts = new BitmapFactory.Options();
            opts.inSampleSize = sample;//采样率
            Bitmap bitmap = BitmapFactory.decodeFile(path,opts);
            iv.setImageBitmap(bitmap);
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}
  • 图片的缩放
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public void opts(View v){
        String path = "mnt/sdcard/1.jpg";
        //显示图片
        Bitmap srcBitmap = BitmapFactory.decodeFile(path);
        ivSrc.setImageBitmap(srcBitmap);
        //准备画纸(大小和材质参照原材料)
        Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(),srcBitmap.getHeight(),srcBitmap.getConfig());
        //准备画板,将画纸放到画板上
        Canvas canvas = new Canvas(copyBitmap);
        //准备画笔
        Paint paint = new Paint();
        //按照一定规则
        Matrix matrix = new Matrix();//1:1画
        //按照比例缩放图片
        matrix.setScale(24.6f,22.8f);
        //将原图像按照规则画到画板上
        canvas.drawBitmap(srcBitmap,matrix,paint);
        //画板有数据了
        ivDest.setImageBitmap(copyBitmap);
    }
  • 图片的位移
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// 位移操作:dx:x方向的增量 dy：y方向的增量
matrix.setTranslate(50, 50);
  • 图片的旋转
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matrix.setRotate(45, srcBitmap.getWidth() / 2f,
		srcBitmap.getHeight() / 2f);
  • 对图片颜色的处理
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public class MainActivity extends Activity implements OnSeekBarChangeListener {
	private ImageView iv;
	private SeekBar skbRed;
	private SeekBar skbGreen;
	private SeekBar skbBlue;
	private float redPercent = 1;
	private float greenPercent = 1;
	private float bluePercent = 1;
	private Bitmap srcBitmap;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		iv = (ImageView) findViewById(R.id.iv);
		skbRed = (SeekBar) findViewById(R.id.skb_red);
		skbGreen = (SeekBar) findViewById(R.id.skb_green);
		skbBlue = (SeekBar) findViewById(R.id.skb_blue);
		skbRed.setOnSeekBarChangeListener(this);
		skbGreen.setOnSeekBarChangeListener(this);
		skbBlue.setOnSeekBarChangeListener(this);
		// 加载图片显示
		String path = "mnt/sdcard/img_small_1.jpg";
		srcBitmap = BitmapFactory.decodeFile(path);
		iv.setImageBitmap(srcBitmap);
	}
	@Override
	public void onProgressChanged(SeekBar seekBar, int progress,
			boolean fromUser) {
		// seekbar进度改变时的回调
	}
	@Override
	public void onStartTrackingTouch(SeekBar seekBar) {
		// 开始拖动seekbar的回调
	}
	@Override
	public void onStopTrackingTouch(SeekBar seekBar) {
		// 停止拖动seekbar的回调
		// 0-100;//0-2
		int progress = seekBar.getProgress();
		float percent = progress / 50f;// (0-2f)
		if (seekBar == skbRed) {
			this.redPercent = percent;
		} else if (seekBar == skbGreen) {
			this.greenPercent = percent;
		} else if (seekBar == skbBlue) {
			this.bluePercent = percent;
		}
		// 去改变图片的颜色
		// 1.去获得图片的拷贝
		Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(),
				srcBitmap.getHeight(), srcBitmap.getConfig());
		Canvas canvas = new Canvas(copyBitmap);
		Matrix matrix = new Matrix();
		// 2.去处理图片的中的颜色数据
		Paint paint = new Paint();
		// 设置画笔的颜色过滤
		// vector:0-2 0:没有 2：最多
		float[] cm = new float[] { 1 * redPercent, 0, 0, 0, 0, // red vector
				0, 1 * greenPercent, 0, 0, 0, // green vector
				0, 0, 1 * bluePercent, 0, 0, // blue vector
				0, 0, 0, 1, 0 // alpha vector
		};
		paint.setColorFilter(new ColorMatrixColorFilter(new ColorMatrix(cm)));
		canvas.drawBitmap(srcBitmap, matrix, paint);
		// 3.将处理的结果展示
		iv.setImageBitmap(copyBitmap);
	}
}
  • canvas相关api
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public class MainActivity extends Activity {
	private ImageView iv;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		iv = (ImageView) findViewById(R.id.iv);
	}
	public void line(View view) {
		// 1.画线
		// 准备画纸
		Bitmap bitmap = Bitmap.createBitmap(320, 320, Config.ARGB_8888);
		// 准备画布
		Canvas canvas = new Canvas(bitmap);
		Paint paint = new Paint();
		canvas.drawLine(10, 10, 200, 200, paint);
		iv.setImageBitmap(bitmap);
	}
	public void rect(View view) {
		// 1.画矩形
		// 准备画纸
		Bitmap bitmap = Bitmap.createBitmap(320, 320, Config.ARGB_8888);
		// 准备画布
		Canvas canvas = new Canvas(bitmap);
		Paint paint = new Paint();
		// 设置画笔的颜色
		paint.setColor(Color.RED);
		// 设置画笔的样式
		paint.setStyle(Style.STROKE);
		paint.setStrokeWidth(10);// 设置粗细
		canvas.drawRect(30, 30, 200, 200, paint);
		iv.setImageBitmap(bitmap);
	}
	public void circle(View view) {
		// 1.画圆形
		// 准备画纸
		Bitmap bitmap = Bitmap.createBitmap(320, 320, Config.ARGB_8888);
		// 准备画布
		Canvas canvas = new Canvas(bitmap);
		Paint paint = new Paint();
		// 设置画笔的颜色
		paint.setColor(Color.RED);
		paint.setAntiAlias(true);// 设置抗锯齿
		float cx = 160;// 圆心的坐标X
		float cy = 160;// 圆心的坐标Y
		float radius = 100;// 半径
		canvas.drawCircle(cx, cy, radius, paint);
		iv.setImageBitmap(bitmap);
	}
	public void arc(View view) {
		// 1.扇形
		// 准备画纸
		Bitmap bitmap = Bitmap.createBitmap(320, 320, Config.ARGB_8888);
		// 准备画布
		Canvas canvas = new Canvas(bitmap);
		Paint paint = new Paint();
		paint.setColor(Color.RED);
		paint.setAntiAlias(true);// 设置抗锯齿
		// 1:矩形
		RectF oval = new RectF(20, 20, 200, 200);
		float startAngle = 0;// 起始角度
		float sweepAngle = 120;// 扫过的角度
		boolean useCenter = false;// 是否画中心部分
		canvas.drawArc(oval, startAngle, sweepAngle, useCenter, paint);
		iv.setImageBitmap(bitmap);
	}
	public void trangle(View view) {
		// 1.多边形
		// 准备画纸
		Bitmap bitmap = Bitmap.createBitmap(320, 320, Config.ARGB_8888);
		// 准备画布
		Canvas canvas = new Canvas(bitmap);
		Paint paint = new Paint();
		paint.setColor(Color.RED);
		paint.setAntiAlias(true);// 设置抗锯齿
		float x1 = 160;
		float y1 = 20;
		float x2 = 140;
		float y2 = 200;
		float x3 = 180;
		float y3 = 200;
		Path path = new Path();
		path.moveTo(x1, y1);// 将画笔移动到点1
		path.lineTo(x2, y2);// 连线点2
		path.arcTo(new RectF(140, 180, 180, 220), 0, 180);
		path.lineTo(x3, y3);// 连线点3
		path.lineTo(x1, y1);// 连线点1
		path.close();
		canvas.drawPath(path, paint);
		iv.setImageBitmap(bitmap);
	}
}
  • 画画板

Menu的写法 :

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<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:id="@+id/action_save"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="保存图片"/>
</menu>

布局写法 :

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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >
        <View
            android:id="@+id/color_red"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:background="#ff0000" />
        <View
            android:id="@+id/color_green"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:background="#00ff00" />
        <View
            android:id="@+id/color_blue"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:background="#0000ff" />
        <View
            android:id="@+id/color_yellow"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:background="#ffff00" />
        <View
            android:id="@+id/color_pink"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:background="#ff99ff" />
    </LinearLayout>
    <!-- 画笔的粗细 -->
    <SeekBar
        android:id="@+id/skb_stroke"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <ImageView
        android:id="@+id/iv"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

Java代码的实现 :

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public class MainActivity extends Activity implements OnClickListener,
		OnSeekBarChangeListener, OnTouchListener {
	private static final String TAG = "MainActivity";
	private View redView;
	private View greenView;
	private View blueView;
	private View yellowView;
	private View pinkView;
	private SeekBar skbStroke;
	private ImageView iv;
	private Bitmap bitmap;
	private Canvas canvas;
	private Paint paint;
	private float startX;
	private float startY;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		redView = findViewById(R.id.color_red);
		greenView = findViewById(R.id.color_green);
		blueView = findViewById(R.id.color_blue);
		yellowView = findViewById(R.id.color_yellow);
		pinkView = findViewById(R.id.color_pink);
		skbStroke = (SeekBar) findViewById(R.id.skb_stroke);
		iv = (ImageView) findViewById(R.id.iv);
		redView.setOnClickListener(this);
		greenView.setOnClickListener(this);
		blueView.setOnClickListener(this);
		yellowView.setOnClickListener(this);
		pinkView.setOnClickListener(this);
		skbStroke.setOnSeekBarChangeListener(this);
		iv.setOnTouchListener(this);
		// 准备画纸画布画笔
		bitmap = Bitmap.createBitmap(320, 320, Config.ARGB_8888);
		canvas = new Canvas(bitmap);
		paint = new Paint();
		canvas.drawColor(Color.WHITE);
	}
	@Override
	public void onClick(View v) {
		switch (v.getId()) {
		// 更改画笔的颜色
		case R.id.color_red:
			paint.setColor(Color.RED);
			break;
		case R.id.color_green:
			paint.setColor(Color.GREEN);
			break;
		case R.id.color_blue:
			paint.setColor(Color.BLUE);
			break;
		case R.id.color_yellow:
			paint.setColor(Color.YELLOW);
			break;
		case R.id.color_pink:
			paint.setColor(0xffff99ff);
			break;
		default:
			break;
		}
	}
	@Override
	public void onProgressChanged(SeekBar seekBar, int progress,
			boolean fromUser) {
		// TODO Auto-generated method stub
	}
	@Override
	public void onStartTrackingTouch(SeekBar seekBar) {
		// TODO Auto-generated method stub
	}
	@Override
	public void onStopTrackingTouch(SeekBar seekBar) {
		// 改变画笔的粗细
		int progress = seekBar.getProgress();// 0-100(1sp--->10sp)
		// paint.setStrokeWidth(progress);
		paint.setStrokeWidth(10 * progress / 100f);
	}
	@Override
	public boolean onTouch(View v, MotionEvent event) {
		// 触摸Imageview的回调
		// 触摸的时候需要绘制图像,并且显示
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:// 1次
			// 1. 手指按下
			startX = event.getX();// 触摸的x坐标
			startY = event.getY();// 触摸的y坐标
			break;
		case MotionEvent.ACTION_MOVE:// 0-多次
			// 2. 手指移动
			float stopX = event.getX();
			float stopY = event.getY();
			// 绘制图像，并且显示到imgeview上
			canvas.drawLine(startX, startY, stopX, stopY, paint);
			// 画纸上有数据了
			iv.setImageBitmap(bitmap);
			// 更新起始点
			startX = stopX;
			startY = stopY;
			break;
		case MotionEvent.ACTION_UP:// 1次
			// 3. 手指抬起
			break;
		default:
			break;
		}
		// 消费触摸事件
		return true;
	}
	// 对应的菜单按钮
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		getMenuInflater().inflate(R.menu.main, menu);
		return super.onCreateOptionsMenu(menu);
	}
	// 菜单按钮的点击事件
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		int itemId = item.getItemId();
		switch (itemId) {
		case R.id.action_save:
			Log.d(TAG, "点击了保存按钮!");
			// 将bitmap存储到本地
			File file = new File(Environment.getExternalStorageDirectory(),
					System.currentTimeMillis() + ".jpg");
			FileOutputStream fos = null;
			try {
				fos = new FileOutputStream(file);
				// 将bitmap压缩到流中
				bitmap.compress(CompressFormat.JPEG, 100, fos);
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			} finally {
				if (fos != null) {
					try {
						fos.close();
					} catch (IOException e) {
						e.printStackTrace();
					}
					fos = null;
				}
			}
			// 模拟 sdcard的挂载
			Intent intent = new Intent(Intent.ACTION_MEDIA_MOUNTED);
			intent.setData(Uri.fromFile(Environment
					.getExternalStorageDirectory()));
			sendBroadcast(intent);
			break;
		default:
			break;
		}
		return super.onOptionsItemSelected(item);
	}
}

  • 播放器的同步和异步

播放网络歌曲权限 :

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

播放器的代码实现 : 

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public class MainActivity extends Activity implements OnSeekBarChangeListener {
	private EditText etPath;
	private SeekBar skbProgress;
	private MediaPlayer player;
	private boolean tracking = false;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		etPath = (EditText) findViewById(R.id.et_path);
		skbProgress = (SeekBar) findViewById(R.id.skb_progress);
		skbProgress.setOnSeekBarChangeListener(this);
	}
	public void play(View view) {
		String path = etPath.getText().toString().trim();
		if (TextUtils.isEmpty(path)) {
			return;
		}
		// 播放音乐
		if (player == null) {
			player = new MediaPlayer();
		}
		// 重置播放器
		player.reset();
		try {
			player.setOnErrorListener(new OnErrorListener() {
				@Override
				public boolean onError(MediaPlayer mp, int what, int extra) {
					System.out.println("what : " + what);
					return false;
				}
			});
			// 设置播放的资源
			player.setDataSource(path);
			player.prepare();// 准备播放
			player.start();// 开始播放
			performProgress();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	private void performProgress() {
		skbProgress.setMax(player.getDuration());// 音乐文件的时长
		new Thread(new Runnable() {
			@Override
			public void run() {
				while (player != null && player.isPlaying()) {
					if (!tracking) {
						// 获得当前的进度
						int currentPosition = player.getCurrentPosition();
						skbProgress.setProgress(currentPosition);//子线程中更新UI
					}
				}
			}
		}).start();
	}
	public void pause(View view) {
		// 暂停
		if (player != null && player.isPlaying()) {
			player.pause();
			((Button) view).setText("继续");
		} else if (player != null) {
			player.start();
			performProgress();
			((Button) view).setText("暂停");
		}
	}
	public void stop(View view) {
		if (player != null) {
			player.stop();
			player.release();// 释放资源
			player = null;
		}
	}
	@Override
	public void onProgressChanged(SeekBar seekBar, int progress,
			boolean fromUser) {
		// TODO Auto-generated method stub
	}
	@Override
	public void onStartTrackingTouch(SeekBar seekBar) {
		// 开始拖动
		tracking = true;
	}
	@Override
	public void onStopTrackingTouch(SeekBar seekBar) {
		// 结束拖动
		tracking = false;
		// 播放对应的位置
		if (player != null) {
			player.seekTo(seekBar.getProgress());
		}
	}
}
  • 声音池
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public class MainActivity extends Activity {
	private SoundPool pool;
	private int soundID;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		int maxStreams = 10;// 声音池中同时可以播放声音的数量
		int streamType = AudioManager.STREAM_MUSIC;
		int srcQuality = 0;
		pool = new SoundPool(maxStreams, streamType, srcQuality);
		// 加载一个声音文件
		soundID = pool.load(this, R.raw.shoot, 1);
	}
	public void shoot(View view) {
		float leftVolume = 1f;
		float rightVolume = 1f;
		int priority = 0;
		int loop = 0;
		float rate = 1;// 播放的速率
		pool.play(soundID, leftVolume, rightVolume, priority, loop, rate);
	}
}
  • 视频播放器

xml界面的简写 :

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<VideoView
    android:id="@+id/vv"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Java代码的实现 :

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public class MainActivity extends Activity {
	private VideoView vv;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		vv = (VideoView) findViewById(R.id.vv);
		MediaController mc = new MediaController(this);
		mc.setAnchorView(vv);
		vv.setMediaController(mc);
		vv.setVideoPath("mnt/sdcard/areyouok.3gp");
		vv.start();
	}
}

  • 拍照
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public class MainActivity extends Activity {
	private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}
	public void takephoto(View view) {
		// create Intent to take a picture and return control to the calling
		// application
		// 意图
		Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);// 去打开系统的照相机
		// 准备一个接收系统拍好照片后的文件路径
		File file = new File(Environment.getExternalStorageDirectory(),
				System.currentTimeMillis() + ".jpg");
		intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file)); // set the
																		// image
																		// file
		// name
		// start the image capture Intent
		// 请求code
		startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
	}
	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		super.onActivityResult(requestCode, resultCode, data);
		if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
			// 为你的某个请求返回的结果
			// 给你数据的Activity设置的结果标记
			// resultCode
			switch (resultCode) {
			case Activity.RESULT_OK:
				// 获取数据成功
				System.out.println("ok");
				break;
			case Activity.RESULT_CANCELED:
				// 用户取消操作
				System.out.println("cancel");
				break;
			default:
				break;
			}
		}
	}
}
  • 传感器指南针
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public class MainActivity extends Activity {
	private SensorManager manager;
	private Sensor sensor;
	private SensorEventListener listener = new SensorEventListener() {
		@Override
		public void onSensorChanged(SensorEvent event) {
			// 1. 获取 传感器的数据
			float[] values = event.values;
			// value
			// values[0]: Azimuth, angle between the magnetic north direction
			// and the y-axis, around the z-axis (0 to 359). 0=North, 90=East,
			// 180=South, 270=West
			float angle = values[0];
			if (angle == 0) {
				System.out.println("北");
			} else if (angle == 90) {
				System.out.println("东");
			} else if (angle == 180) {
				System.out.println("南");
			} else if (angle == 270) {
				System.out.println("西");
			} else if (angle > 0 && angle < 90) {
				System.out.println("东北");
			} else if (angle > 90 && angle < 180) {
				System.out.println("东南");
			} else if (angle > 180 && angle < 270) {
				System.out.println("西南");
			} else if (angle > 270 && angle < 360) {
				System.out.println("西北");
			}
		}
		@Override
		public void onAccuracyChanged(Sensor sensor, int accuracy) {
			// 1. 传感器的精确度发送改变时
		}
	};
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		// 传感器的管理者
		manager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
		// List<Sensor> list = manager.getSensorList(Sensor.TYPE_ALL);
		// for (Sensor sensor : list) {
		// System.out.println(sensor.getName());
		// }
		// 获得光的传感器
		sensor = manager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
	}
	@Override
	protected void onResume() {
		super.onResume();
		// 1:监听传感器
		// 2:哪个传感器
		// 3:采样频率
		manager.registerListener(listener, sensor,
				SensorManager.SENSOR_DELAY_NORMAL);
	}
	@Override
	protected void onPause() {
		super.onPause();
		manager.unregisterListener(listener);
	}
}