问题描述

保存一个图像连同它的thuml然后显示在imageView中

我想保存一个从相机拍摄的照片，然后把照片和 Thumb 保存在 sdCard 中，然后把它们显示在一个 imageView 中。后来给出空指针错误。

imageBitmap = Bitmap.createScaledBitmap(imageBitmap, 40, 40, false);

哪里出错了？

      {
            Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
            try
            {
              if (title.getText().toString().equals(""))
              {
                displayAlert("Please Input Title First","Error!");
              }
              else
              {
                Integer val = myMisc.miscId ;
                String fileName = "image" + "_" + title.getText().toString()+"_" + val.toString();
                photo = this.createFile(fileName, ".jpg");
                myMisc.filename = photo.getAbsolutePath();
                intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photo));
                startActivityForResult(intent, RESULT_CAMERA_SELECT);
              }
            }
            catch(Exception e)
            {
                Log.v("Error", "Can't create file to take picture!");
                displayAlert("Can't create file to take picture!","SDCard Error!");
            }
        }
public synchronized void onActivityResult(final int requestCode, int resultCode, final Intent data)
    {
       if (resultCode == Activity.RESULT_OK)
       {
           if (requestCode == RESULT_CAMERA_SELECT)
           {
               try
               {
                   saveImage();
               }
               catch (IOException e)
               {
                   e.printStackTrace();
               }
           }
 public static int calculateInSampleSize(
            BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {
        if (width > height) {
            inSampleSize = Math.round((float)height / (float)reqHeight);
        } else {
            inSampleSize = Math.round((float)width / (float)reqWidth);
        }
    }
    return inSampleSize;
}
    public void saveImage() throws IOException
    {
      try
        {
           FileInputStream is2 = new FileInputStream(photo);
           final BitmapFactory.Options options = new BitmapFactory.Options();
           options.inJustDecodeBounds = true;
           Bitmap imageBitmap = BitmapFactory.decodeStream(is2, null, options);
           options.inSampleSize = calculateInSampleSize(options, 40, 40);
           options.inJustDecodeBounds = false;
           imageBitmap = BitmapFactory.decodeStream(is2 ,null, options);
           imageBitmap = Bitmap.createScaledBitmap(imageBitmap, 40, 40, false);
           Integer val = myMisc.miscId;
           String fileName = ".thumbImage" + "_" + title.getText().toString()+ "_" + val.toString();
           photo = this.createFile(fileName, ".jpg");
           myMisc.thumbFileName = photo.getAbsolutePath();
        try {
           FileOutputStream out = new FileOutputStream(photo);
           imageBitmap.compress(Bitmap.CompressFormat.PNG, 90, out);
            } catch (Exception e) {
           e.printStackTrace();
            }
            is2.close();
            Uri uri = Uri.fromFile(photo);
            photo = null;
            imageBitmap = null;
            imageView.setImageURI(uri);
        }catch(Exception e)
        {
            displayAlert("Can't create file to take picture!","SD Card Error");
        }
    }

解决方案

public static Bitmap getSmallBitmap(String filePath) {

    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(filePath, options);

    // Calculate inSampleSize
    options.inSampleSize = 2;

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;

    Bitmap bm = BitmapFactory.decodeFile(filePath, options);
    if(bm == null){
        return  null;
    }
    ByteArrayOutputStream baos = null ;
    try{
        baos = new ByteArrayOutputStream();
        bm.compress(Bitmap.CompressFormat.JPEG, 100, baos);
    }finally{
        try {
            if(baos != null)
                baos.close() ;
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return bm ;

}

这样可以从文件中得到图片。

Intent mediaScanIntent = new Intent("android.intent.action.MEDIA_SCANNER_SCAN_FILE");
            File f = new File(mCurrentPhotoPath);
            Uri contentUri = Uri.fromFile(f);
            mediaScanIntent.setData(contentUri);
            this.sendBroadcast(mediaScanIntent);

上面的code可以把图片保存到图片库中

解决方案二：

错误是 Bitmap imageBitmap = BitmapFactory.decodeStream(is2, null, options); 被解码了俩次。