Android多媒体之调用摄像头和从本地相册中选择图片

概述：

这个例程的实现的功能是：拍照，自动压缩图片，以及从本地相册选择图片。
需要加载权限：

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

demo：

public class MainActivity extends Activity implements View.OnClickListener {    private Button mButtonTakePhoto;    private Button mButtonGetPhoto;    private ImageView mImageViewPhoto;    private File mFile;//存储图片的文件    public static final int GET_PIC_FROM_CAMERA = 0x123;    public static final int GET_PIC_FROM_GALLERY = 0X124;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mButtonTakePhoto = (Button) findViewById(R.id.button_take_photo);        mButtonGetPhoto = (Button) findViewById(R.id.button_get_photo);        mImageViewPhoto = (ImageView) findViewById(R.id.imageView_camera);//        mImageViewPhoto.setImageURI(Uri.fromFile(new File("/mnt/sdcard/1442309575248.jpg")));        mButtonTakePhoto.setOnClickListener(this);        mButtonGetPhoto.setOnClickListener(this);    }    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (requestCode) {            case GET_PIC_FROM_CAMERA:                if (resultCode == RESULT_OK) {                    ImageZip.zipImage(mFile.getAbsolutePath());//压缩图片                    mImageViewPhoto.setImageURI(Uri.fromFile(mFile));                }                break;            case GET_PIC_FROM_GALLERY:                if(resultCode==RESULT_OK){                    getImageFromGallery(data);                }                break;        }    }    /**     * 从本地相册中选择并得到相片     */    private void getImageFromGallery(Intent data) {        Uri selectedImage = data.getData();        //用一个String数组存储相册所有图片        String[] filePathColumn = { MediaStore.Images.Media.DATA };        //用一个Cursor对象的到相册的所有内容        Cursor cursor = getContentResolver().query(selectedImage,                filePathColumn, null, null, null);        cursor.moveToFirst();        //得到选中图片下标        int columnIndex = cursor.getColumnIndex(filePathColumn[0]);        //得到所选的相片路径        String picturePath = cursor.getString(columnIndex);        //关闭Cursor，以免占用资源        cursor.close();        ImageZip.zipImage(picturePath);//一般相册中图片太大，不能直接显示，需要压缩图片        //用一个ImageView展示该图片        mImageViewPhoto.setImageBitmap(BitmapFactory.decodeFile(picturePath));    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button_take_photo:                getPictureFromCamera();                break;            case R.id.button_get_photo:                /*Intent intent = new Intent(Intent.ACTION_GET_CONTENT);                intent.setType("");                startActivityForResult(intent, GET_PIC_FROM_GALLERY);*/                //左起参数：选择行为权限，系统本地相册URI路径                Intent i = new Intent(                        Intent.ACTION_PICK,                        android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);                //向onActivityResult发送intent，requestCode为GET_PIC_FROM_GALLERY                startActivityForResult(i, GET_PIC_FROM_GALLERY);                break;        }    }    /**     * 向onActivityResult发出请求，的到拍摄生成的图片     */    private void getPictureFromCamera() {        Intent intent = new Intent();        intent.setAction(MediaStore.ACTION_IMAGE_CAPTURE);        //确定存储拍照得到的图片文件路径        mFile = new File(Environment.getExternalStorageDirectory(), System.currentTimeMillis() + ".jpg");        try {            mFile.createNewFile();        } catch (IOException e) {            e.printStackTrace();        }        //加载Uri型的文件路径        intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(mFile));        //向onActivityResult发送intent，requestCode为GET_PIC_FROM_CAMERA        startActivityForResult(intent, GET_PIC_FROM_CAMERA);    }}

压缩图片的类：

public class ImageZip {    /**     * 压缩图片的方法     */    public static void zipImage(String savePath) {        BitmapFactory.Options options = new BitmapFactory.Options();        options.inJustDecodeBounds = true;        BitmapFactory.decodeFile(savePath, options);        options.inSampleSize = computeInitialSampleSize(options, 480, 480 * 960);        options.inJustDecodeBounds = false;        Bitmap bitmap = BitmapFactory.decodeFile(savePath, options);        try {            FileOutputStream fos = new FileOutputStream(savePath);            bitmap.compress(Bitmap.CompressFormat.JPEG, 90, fos);            fos.flush();            fos.close();        } catch (IOException e) {            e.printStackTrace();        }        bitmap.recycle();        bitmap = null;        System.gc();    }    public static Bitmap getZipImage(String savePath){        BitmapFactory.Options options = new BitmapFactory.Options();        options.inJustDecodeBounds = true;        BitmapFactory.decodeFile(savePath, options);        options.inSampleSize = computeInitialSampleSize(options, 480, 480 * 960);        options.inJustDecodeBounds = false;        Bitmap bitmap = BitmapFactory.decodeFile(savePath, options);        bitmap.recycle();        bitmap = null;        System.gc();        return bitmap;    }    public int computeSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {        int initialSize = computeInitialSampleSize(options, minSideLength,                maxNumOfPixels);        int roundedSize;        if (initialSize <= 8) {            roundedSize = 1;            while (roundedSize < initialSize) {                roundedSize <<= 1;            }        } else {            roundedSize = (initialSize + 7) / 8 * 8;        }        return roundedSize;    }    public static int computeInitialSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {        double w = options.outWidth;        double h = options.outHeight;        int lowerBound = (maxNumOfPixels == -1) ? 1 : (int) Math.ceil(Math                .sqrt(w * h / maxNumOfPixels));        int upperBound = (minSideLength == -1) ? 128 : (int) Math.min(                Math.floor(w / minSideLength), Math.floor(h / minSideLength));        if (upperBound < lowerBound) {            // return the larger one when there is no overlapping zone.            return lowerBound;        }        if ((maxNumOfPixels == -1) && (minSideLength == -1)) {            return 1;        } else if (minSideLength == -1) {            return lowerBound;        } else {            return upperBound;        }    }}

布局：

<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">    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">        <Button            android:id="@+id/button_take_photo"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="Take Photo"/>        <Button            android:id="@+id/button_get_photo"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="Get From Gallery"/>    </LinearLayout>    <ImageView        android:id="@+id/imageView_camera"        android:layout_width="match_parent"        android:layout_height="match_parent"/></LinearLayout>

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