我正在尝试从画廊获得图像。它给我的图像是位图。我希望将图像保存在.jpg文件中,以便可以将文件名保存在数据库中。
我遵循了本教程:
http://www.theappguruz.com/blog/android-take-photo-camera-gallery-code-sample
画廊图片选择代码:
@SuppressWarnings("deprecation")
private void onSelectFromGalleryResult(Intent data) {
Bitmap bm=null;
if (data != null) {
try {
bm = MediaStore.Images.Media.getBitmap(getApplicationContext().getContentResolver(), data.getData());
} catch (IOException e) {
e.printStackTrace();
}
}
Uri selectedImage = data.getData();
String[] filePath = {MediaStore.Images.Media.DATA};
Cursor c = getContentResolver().query(selectedImage, filePath, null, null, null);
c.moveToFirst();
int columnIndex = c.getColumnIndex(filePath[0]);
String picturePath = c.getString(columnIndex);
c.close();
File file = new File(picturePath);// error line
mProfileImage = file;
profile_image.setImageBitmap(bm);
}
我试过了但是我在文件上得到了空指针。
例外情况:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'char[] java.lang.String.toCharArray()' on a null object reference
另外,我也不想将此新创建的文件保存在外部存储中。这应该是一个临时文件。我怎样才能做到这一点?
谢谢..
最佳答案
好消息是您比想像的要完成得多!
Bitmap bm=null;
if (data != null) {
try {
bm = MediaStore.Images.Media.getBitmap(getApplicationContext().getContentResolver(), data.getData());
} catch (IOException e) {
e.printStackTrace();
}
}
此时,如果为
bm != null
,则您有一个Bitmap对象。位图是可以使用的Android通用图像对象。它实际上实际上已经是.jpg格式,因此您只需要将其写入文件即可。您想将其写入临时文件,因此我将执行以下操作:File outputDir = context.getCacheDir(); // Activity context
File outputFile = File.createTempFile("prefix", "extension", outputDir); // follow the API for createTempFile
无论如何,这时将
Bitmap
写入文件非常简单。ByteArrayOutputStream stream = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 100, stream); //replace 100 with desired quality percentage.
byte[] byteArray = stream.toByteArray();
现在您有了一个字节数组。我将其保留在文件中。
如果您希望临时文件消失,请参见此处以获取更多信息:https://developer.android.com/reference/java/io/File.html#deleteOnExit()
Bitmap bm=null;
if (data != null) {
try {
bm = MediaStore.Images.Media.getBitmap(getApplicationContext().getContentResolver(), data.getData());
} catch (IOException e) {
e.printStackTrace();
}
}
if (bm != null) { // sanity check
File outputDir = context.getCacheDir(); // Activity context
File outputFile = File.createTempFile("image", "jpg", outputDir); // follow the API for createTempFile
FileOutputStream stream = new FileOutputStream (outputFile, false); // Add false here so we don't append an image to another image. That would be weird.
// This line actually writes a bitmap to the stream. If you use a ByteArrayOutputStream, you end up with a byte array. If you use a FileOutputStream, you end up with a file.
bm.compress(Bitmap.CompressFormat.JPEG, 100, stream);
stream.close(); // cleanup
}
希望对您有所帮助!