Question

我正在尝试从现有URI创建位图，旋转位图并将其保存到与JPEG文件相同的位置。在尝试了几种解决方案之后，这是我当前的代码：

try {
    // Get the Bitmap from the known URI. This seems to work.
    Bitmap bmp = MediaStore.Images.Media.getBitmap(this.getContentResolver(), this.currUserImgUri);

    // Rotate the Bitmap thanks to a rotated matrix. This seems to work.
    Matrix matrix = new Matrix();
    matrix.postRotate(-90);
    bmp = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), matrix, true);

    // Create an output stream which will write the Bitmap bytes to the file located at the URI path.
    File imageFile = new File(this.currUserImgUri.getPath());
    FileOutputStream fOut = new FileOutputStream(imageFile); // --> here an Exception is catched; see below.
    // The following doesn't work neither:
    // FileOutputStream fOut = new FileOutputStream(this.currUserImgUri.getPath());

    // Write the compressed file into the output stream
    bmp.compress(Bitmap.CompressFormat.JPEG, 85, fOut);
    fOut.flush();
    fOut.close();

} catch (FileNotFoundException e1) {
    e1.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

捕获的例外情况如下：

java.io.FileNotFoundException：/ external / images / media / 8439：open failed：ENOENT（没有这样的文件或目录）

如果我刚刚创建文件并且可以访问其URI，那么有人可以向我解释该文件不存在吗？

也许我对此一切都错了？在这种情况下，根据其URI将旋转图像保存到同一位置的正确方法是什么？

Answer 1

嘿，你可以这样做，用来将位图写入文件。

// Rotate the Bitmap thanks to a rotated matrix. This seems to work.
   Bitmap bitmap = MediaStore.Images.Media.getBitmap(getContext().getContentResolver(), photoURI);
   Matrix matrix = new Matrix();
   matrix.postRotate(90);
   Bitmap bmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
   //learn content provider for more info
   OutputStream os=getContext().getContentResolver().openOutputStream(photoURI);
   bmp.compress(Bitmap.CompressFormat.PNG,100,os);

不要忘记刷新和关闭输出流。实际上，内容提供商拥有自己的uri计划。

Answer 2

这是一个Kotlin扩展函数，给定图像的URI，它将旋转图像并将其再次存储在相同的URI中。

fun Context.rotateImage(imageUri: uri, angle: Float) {

    // (1) Load from where the URI points into a bitmap    
    val bitmap = MediaStore.Images.Media.getBitmap(contentResolver, imageUri)

    // (2) Rotate the bitmap
    val rotatedBitmap = bitmap.rotatedBy(angle)

    // (3) Write the bitmap to where the URI points
    try {
        contentResolver.openOutputStream(imageUri).also {
            rotateBitmap.compress(Bitmap.CompressFormat.PNG, 100, it)
        }
    } catch (e: IOException) {
        // handle exception
    }
}

fun Bitmap.rotatedBy(angle: Float) {
    val matrix = Matrix().apply { postRotate(angle) }
    return Bitmap.createBitmap(this, 0, 0, width, height, matrix, true)
}

你可以改为定义函数来接受上下文作为参数，使接收器对你来说很方便。

从URI旋转图像并将旋转的图像保存到同一位置

2 个答案: