Android 调用系统相机拍照的返回结果

时间：03-02来源：作者：点击数：12

1.打开相机的Intent Action: MediaStore.ACTION_IMAGE_CAPTURE，下面为它的注释：

 /**
 * Standard Intent action that can be sent to have the camera application
 * capture an image and return it.
 * <p>
 * The caller may pass an extra EXTRA_OUTPUT to control where this image will be written.
 * If the EXTRA_OUTPUT is not present, then a small sized image is returned as a Bitmap
 * object in the extra field. This is useful for applications that only need a small image.
 * If the EXTRA_OUTPUT is present, then the full-sized image will be written to the Uri
 * value of EXTRA_OUTPUT.
 * As of {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this uri can also be supplied through
 * {@link android.content.Intent#setClipData(ClipData)}. If using this approach, you still must
 * supply the uri through the EXTRA_OUTPUT field for compatibility with old applications.
 * If you don't set a ClipData, it will be copied there for you when calling
 * {@link Context#startActivity(Intent)}.
 *
 * <p>Note: if you app targets {@link android.os.Build.VERSION_CODES#M M} and above
 * and declares as using the {@link android.Manifest.permission#CAMERA} permission which
 * is not granted, then atempting to use this action will result in a {@link
 * java.lang.SecurityException}.
 *
 *  @see #EXTRA_OUTPUT
 */
@SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
public final static String ACTION_IMAGE_CAPTURE = "android.media.action.IMAGE_CAPTURE";

从注释可以知道，该Action会打开照相机拍照然后返回结果，如果在没有设置额外的控制图片存储路径的参数MediaStore.EXTRA_OUTPUT情况下，返回的结果将是一个小的Bitmap，这仅仅只适合于应用程序需要一张小的图片的时候；如果设置了MediaStore.EXTRA_OUTPUT，那么将保存整个大小的到指定的Uri中。

没有设置MediaStore.EXTRA_OUTPUT的情况下:

public void onTakePhotoClick(View view) {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
        Bundle extras = data.getExtras();
        mImageBitmap = (Bitmap) extras.get("data");
        mThumbView.setImageBitmap(mImageBitmap);
    }
}

从(Bitmap) extras.get("data")直接就可以获取到返回的图片，但这种图片小且质量很差，下面为测试的返回结果：

设置MediaStore.EXTRA_OUTPUT的情况下，需要添加

takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(new File("/mnt/sdcard/DCIM/Album/1.jpg")));

附加：/mnt/sdcard/DCIM/Album/1.jpg为图片的存储地址。

2.将图片添加到图库中

这样拍的照片并不会出现在系统的图库中，但经过一些测试，有些手机关机重启之后，相册中会出现这些照片，原因是重启之后系统扫描了文件夹，将图片添加到了多媒体数据库中。下面为将图片添加到多媒体数据中的方法：

2.1通过发送广播给系统将文件添加到多媒体数据库中：

 /*
* Request the media scanner to scan a file and add it to the media database.
 */
private void scanFile() {
    Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
    intent.setData(Uri.fromFile(new File("/mnt/sdcard/DCIM/Album/1.jpg")));
    sendBroadcast(intent);
}

这段代码会启动一个叫MediaScannerBroadcast广播，但该广播并不会去扫描文件，是交给一个叫MediaScannerService服务去完成的，另外上面的Uri也可以换成文件夹的路径。

2.2手动将图片插入到媒体数据中：

Bitmap bm = BitmapFactory.decodeFile("/mnt/sdcard/DCIM/Album/1.jpg");

String stringUrl = MediaStore.Images.Media.insertImage(getContentResolver(), bm, "", "");

下面为insertImage(ContentResolver cr, String imagePath,String name, String description)的源码：

<span style="font-size:18px;"> /**
 * Insert an image and create a thumbnail for it.
 *
 * @param cr The content resolver to use
 * @param source The stream to use for the image
 * @param title The name of the image
 * @param description The description of the image
 * @return The URL to the newly created image, or <code>null</code> if the image failed to be stored
 *              for any reason.
 */
public static final String insertImage(ContentResolver cr, Bitmap source,
                                       String title, String description) {
    ContentValues values = new ContentValues();
    values.put(Images.Media.TITLE, title);
    values.put(Images.Media.DESCRIPTION, description);
    values.put(Images.Media.MIME_TYPE, "image/jpeg");

    Uri url = null;
    String stringUrl = null;    /* value to be returned */

    try {
        url = cr.insert(EXTERNAL_CONTENT_URI, values);

        if (source != null) {
            OutputStream imageOut = cr.openOutputStream(url);
            try {
                source.compress(Bitmap.CompressFormat.JPEG, 50, imageOut);
            } finally {
                imageOut.close();
            }

            long id = ContentUris.parseId(url);
            // Wait until MINI_KIND thumbnail is generated.
            Bitmap miniThumb = Images.Thumbnails.getThumbnail(cr, id,
                    Images.Thumbnails.MINI_KIND, null);
            // This is for backward compatibility.
            Bitmap microThumb = StoreThumbnail(cr, miniThumb, id, 50F, 50F,
                    Images.Thumbnails.MICRO_KIND);
        } else {
            Log.e(TAG, "Failed to create thumbnail, removing original");
            cr.delete(url, null, null);
            url = null;
        }
    } catch (Exception e) {
        Log.e(TAG, "Failed to insert image", e);
        if (url != null) {
            cr.delete(url, null, null);
            url = null;
        }
    }

    if (url != null) {
        stringUrl = url.toString();
    }

    return stringUrl;
}</span>

从源码可以知道，其实是通过多媒体的内容提供者将图片插入到了数据库中，另外将图片插入到多媒体数据库中之后，我们需要获取图片，通过返回结果stringUrl 可以知道，它就是图片存储在媒体数据库中的路径，因此：

String path = getPath(Uri.parse(stringUrl), "date_added desc limit 1");

/**
 * 获得媒体数据库中图片的路径
 */
private String getPath(Uri uri, String sortOrder) {
    String path = null;
    Cursor cursor = getContentResolver().query(uri, null, null, null, sortOrder);
    if (cursor != null) {
        if (cursor.getCount() > 0) {
            while (cursor.moveToNext()) {
                path = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.DATA));
            }
        }
        cursor.close();
    }
    return path;
}