onActivityResult 数据为空，带相机

Question

我正在尝试使用户能够从他的相机中拍照并将其存储在内部内存中并且它正在工作。问题是当我尝试调整该图像的大小时，我创建了一个方法并找到了实现该方法的方法，但问题是 onActivity 仅在数据上返回 null，因此我无法访问它

  public void takePicture() {
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new      Date());
    File imagesFolder = new File(Environment.getExternalStorageDirectory(), "App");
    imagesFolder.mkdirs();

    Intent imageIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
    File image = new File(imagesFolder, "QR_" + timeStamp + ".jpg");
    Uri uriSavedImage = Uri.fromFile(image);
    uriString=uriSavedImage.toString();
    imageIntent.putExtra(MediaStore.EXTRA_OUTPUT, uriSavedImage);
    startActivityForResult(imageIntent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);

}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode==CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE){
        Uri uri =data.getData();
        changeImageSize(uri,500,500);


    }
}

 private Bitmap changeImageSize(Uri fileUri, int width, int height) {
    Bitmap bitmap = null;
    File imgFile = new File(getRealPathFromURI(getApplicationContext(),fileUri));
    if (imgFile.exists()) {
        bitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath());
    }
    if (bitmap != null) {
        return bitmap = (Bitmap.createScaledBitmap(bitmap, width, height, false));
    }
    return null;
}



  public String getRealPathFromURI(Context context, Uri contentUri) {
    Cursor cursor = getActivity().getContentResolver().query(contentUri, null, null, null, null);
    cursor.moveToFirst();
    String document_id = cursor.getString(0);
    document_id = document_id.substring(document_id.lastIndexOf(":")+1);
    cursor.close();

    cursor = getActivity().getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,null
            , MediaStore.Images.Media._ID + " = ? ", new String[]{document_id}, null);
    cursor.moveToFirst();
    String path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
    cursor.close();

    return path;
}

我尝试添加一些在下面发布的解决方案，现在我的 getRealPathFromURI 方法出现错误，说明如下：

Logcat

Attempt to invoke interface method 'boolean android.database.Cursor.moveToFirst()' on a null object reference
java.lang.RuntimeException: Failure delivering result 
ResultInfo{who=null, request=65636, result=-1, data=null} to activity {com.app/com.app.MainPostLogin}: java.lang.NullPointerException: 
Attempt to invoke interface method 'boolean android.database.Cursor.moveToFirst()' on a null object reference

Answer 1

当您将 Uri 传递给相机时，它不会返回任何数据。将此文件存储在局部变量File image = new File(imagesFolder, "QR_" + timeStamp + ".jpg"); 中并尝试

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode==CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE && resultCode == RESULT_OK){
    changeImageSize(Uri.fromFile(image),500,500);
    }
}

Answer 2

这是我在项目中用于调整图像大小的工作代码。 创建此方法（只需复制粘贴）：

private String decodeFile(String path, int DESIREDWIDTH, int DESIREDHEIGHT) {
    String strMyImagePath = null;
    Bitmap scaledBitmap = null;

    try {
        // Part 1: Decode image
        Bitmap unscaledBitmap = ScalingUtilities.decodeFile(path, DESIREDWIDTH, DESIREDHEIGHT, ScalingUtilities.ScalingLogic.FIT);

        if (!(unscaledBitmap.getWidth() <= DESIREDWIDTH && unscaledBitmap.getHeight() <= DESIREDHEIGHT)) {
            // Part 2: Scale image
            scaledBitmap = ScalingUtilities.createScaledBitmap(unscaledBitmap, DESIREDWIDTH, DESIREDHEIGHT, ScalingUtilities.ScalingLogic.FIT);
        } else {
            unscaledBitmap.recycle();
            return path;
        }

        // Store to tmp file

        String extr = Environment.getExternalStorageDirectory().toString();
        File mFolder = new File(extr + "/TMMFOLDER");
        if (!mFolder.exists()) {
            mFolder.mkdir();
        }

        String s = "tmp.png";

        File f = new File(mFolder.getAbsolutePath(), s);

        strMyImagePath = f.getAbsolutePath();
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(f);
            scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 75, fos);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {

            e.printStackTrace();
        } catch (Exception e) {

            e.printStackTrace();
        }

        scaledBitmap.recycle();
    } catch (Throwable e) {
    }

    if (strMyImagePath == null) {
        return path;
    }
    return strMyImagePath;
}

创建这个类（复制粘贴）：

package com.katariya.pomoc.utils;

/**
 * Created by Danish.sharma on 5/31/2016.
 */
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;

/**
 * Class containing static utility methods for bitmap decoding and scaling
 *
 * @author
 */
public class ScalingUtilities {

    /**
     * Utility function for decoding an image resource. The decoded bitmap will
     * be optimized for further scaling to the requested destination dimensions
     * and scaling logic.
     *
     * @param res The resources object containing the image data
     * @param resId The resource id of the image data
     * @param dstWidth Width of destination area
     * @param dstHeight Height of destination area
     * @param scalingLogic Logic to use to avoid image stretching
     * @return Decoded bitmap
     */
    public static Bitmap decodeResource(Resources res, int resId, int dstWidth, int dstHeight,
                                        ScalingLogic scalingLogic) {
        Options options = new Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);
        options.inJustDecodeBounds = false;
        options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth,
                dstHeight, scalingLogic);
        Bitmap unscaledBitmap = BitmapFactory.decodeResource(res, resId, options);

        return unscaledBitmap;
    }
    public static Bitmap decodeFile(String path, int dstWidth, int dstHeight,
                                    ScalingLogic scalingLogic) {
        Options options = new Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(path, options);
        options.inJustDecodeBounds = false;
        options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth,
                dstHeight, scalingLogic);
        Bitmap unscaledBitmap = BitmapFactory.decodeFile(path, options);

        return unscaledBitmap;
    }

    /**
     * Utility function for creating a scaled version of an existing bitmap
     *
     * @param unscaledBitmap Bitmap to scale
     * @param dstWidth Wanted width of destination bitmap
     * @param dstHeight Wanted height of destination bitmap
     * @param scalingLogic Logic to use to avoid image stretching
     * @return New scaled bitmap object
     */
    public static Bitmap createScaledBitmap(Bitmap unscaledBitmap, int dstWidth, int dstHeight,
                                            ScalingLogic scalingLogic) {
        Rect srcRect = calculateSrcRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(),
                dstWidth, dstHeight, scalingLogic);
        Rect dstRect = calculateDstRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(),
                dstWidth, dstHeight, scalingLogic);
        Bitmap scaledBitmap = Bitmap.createBitmap(dstRect.width(), dstRect.height(),
                Config.ARGB_8888);
        Canvas canvas = new Canvas(scaledBitmap);
        canvas.drawBitmap(unscaledBitmap, srcRect, dstRect, new Paint(Paint.FILTER_BITMAP_FLAG));

        return scaledBitmap;
    }

    /**
     * ScalingLogic defines how scaling should be carried out if source and
     * destination image has different aspect ratio.
     *
     * CROP: Scales the image the minimum amount while making sure that at least
     * one of the two dimensions fit inside the requested destination area.
     * Parts of the source image will be cropped to realize this.
     *
     * FIT: Scales the image the minimum amount while making sure both
     * dimensions fit inside the requested destination area. The resulting
     * destination dimensions might be adjusted to a smaller size than
     * requested.
     */
    public static enum ScalingLogic {
        CROP, FIT
    }

    /**
     * Calculate optimal down-sampling factor given the dimensions of a source
     * image, the dimensions of a destination area and a scaling logic.
     *
     * @param srcWidth Width of source image
     * @param srcHeight Height of source image
     * @param dstWidth Width of destination area
     * @param dstHeight Height of destination area
     * @param scalingLogic Logic to use to avoid image stretching
     * @return Optimal down scaling sample size for decoding
     */
    public static int calculateSampleSize(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
                                          ScalingLogic scalingLogic) {
        if (scalingLogic == ScalingLogic.FIT) {
            final float srcAspect = (float)srcWidth / (float)srcHeight;
            final float dstAspect = (float)dstWidth / (float)dstHeight;

            if (srcAspect > dstAspect) {
                return srcWidth / dstWidth;
            } else {
                return srcHeight / dstHeight;
            }
        } else {
            final float srcAspect = (float)srcWidth / (float)srcHeight;
            final float dstAspect = (float)dstWidth / (float)dstHeight;

            if (srcAspect > dstAspect) {
                return srcHeight / dstHeight;
            } else {
                return srcWidth / dstWidth;
            }
        }
    }

    /**
     * Calculates source rectangle for scaling bitmap
     *
     * @param srcWidth Width of source image
     * @param srcHeight Height of source image
     * @param dstWidth Width of destination area
     * @param dstHeight Height of destination area
     * @param scalingLogic Logic to use to avoid image stretching
     * @return Optimal source rectangle
     */
    public static Rect calculateSrcRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
                                        ScalingLogic scalingLogic) {
        if (scalingLogic == ScalingLogic.CROP) {
            final float srcAspect = (float)srcWidth / (float)srcHeight;
            final float dstAspect = (float)dstWidth / (float)dstHeight;

            if (srcAspect > dstAspect) {
                final int srcRectWidth = (int)(srcHeight * dstAspect);
                final int srcRectLeft = (srcWidth - srcRectWidth) / 2;
                return new Rect(srcRectLeft, 0, srcRectLeft + srcRectWidth, srcHeight);
            } else {
                final int srcRectHeight = (int)(srcWidth / dstAspect);
                final int scrRectTop = (int)(srcHeight - srcRectHeight) / 2;
                return new Rect(0, scrRectTop, srcWidth, scrRectTop + srcRectHeight);
            }
        } else {
            return new Rect(0, 0, srcWidth, srcHeight);
        }
    }

    /**
     * Calculates destination rectangle for scaling bitmap
     *
     * @param srcWidth Width of source image
     * @param srcHeight Height of source image
     * @param dstWidth Width of destination area
     * @param dstHeight Height of destination area
     * @param scalingLogic Logic to use to avoid image stretching
     * @return Optimal destination rectangle
     */
    public static Rect calculateDstRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
                                        ScalingLogic scalingLogic) {
        if (scalingLogic == ScalingLogic.FIT) {
            final float srcAspect = (float)srcWidth / (float)srcHeight;
            final float dstAspect = (float)dstWidth / (float)dstHeight;

            if (srcAspect > dstAspect) {
                return new Rect(0, 0, dstWidth, (int)(dstWidth / srcAspect));
            } else {
                return new Rect(0, 0, (int)(dstHeight * srcAspect), dstHeight);
            }
        } else {
            return new Rect(0, 0, dstWidth, dstHeight);
        }
    }

}

这是调整图片大小的主线

 Bitmap bmp = BitmapFactory.decodeFile(decodeFile(file.toString(), 600, 600));
                                imageView.setImageBitmap(bmp);

查看我的 onActivityResult 我如何以及在何处使用这些行：

  @Override
    protected void onActivityResult(int requestCode, int resultCode, final Intent data) {
        super.onActivityResult(requestCode, resultCode, data);


        if (requestCode == PICK_IMAGE_REQUEST) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    runOnUiThread(new Runnable() {
                        public void run() {
                            try {
                                Bitmap thumbnail = (Bitmap) data.getExtras().get("data");
                                ByteArrayOutputStream bytes = new ByteArrayOutputStream();
                                thumbnail.compress(Bitmap.CompressFormat.JPEG, 90, bytes);

                                File destination = new File(Environment.getExternalStorageDirectory() + "/Guesp");
                                if (!destination.exists()) {
                                    File f = new File("/sdcard/POMOC/");
                                    f.mkdir();
                                }
                                File file = new File(new File("/sdcard/POMOC/"), System.currentTimeMillis() + ".jpg");

                                FileOutputStream fo;
                                try {
                                    file.createNewFile();
                                    fo = new FileOutputStream(file);
                                    fo.write(bytes.toByteArray());
                                    fo.close();
                                    picturePath = file.toString();
                                } catch (FileNotFoundException e) {
                                    e.printStackTrace();
                                } catch (IOException e) {
                                    e.printStackTrace();
                                }

                                Bitmap bmp = BitmapFactory.decodeFile(decodeFile(file.toString(), 600, 600));
                                img_profilePhoto.setImageBitmap(bmp);
                            } catch (Exception e) {

                                e.printStackTrace();
                            }
                        }
                    });
                }
            }).start();
        }
    }

就是这样。