我正在研究从web服务器下载图像的功能，在屏幕上显示它，如果用户希望保持图像，将其保存在SD卡的某个文件夹中。有没有一种简单的方法来获取位图并将其保存到我选择的SD卡文件夹中?
我的问题是，我可以下载图像，在屏幕上显示为位图。我能够找到的将图像保存到特定文件夹的唯一方法是使用FileOutputStream，但这需要一个字节数组。我不知道如何转换(如果这是正确的方式)从位图到字节数组，所以我可以使用FileOutputStream写入数据。
我的另一个选择是使用MediaStore:
MediaStore.Images.Media.insertImage(getContentResolver(), bm,
barcodeNumber + ".jpg Card Image", barcodeNumber + ".jpg Card Image");
它可以很好地保存到SD卡，但不允许您自定义文件夹。
当前回答
try (FileOutputStream out = new FileOutputStream(filename)) {
bmp.compress(Bitmap.CompressFormat.PNG, 100, out); // bmp is your Bitmap instance
// PNG is a lossless format, the compression factor (100) is ignored
} catch (IOException e) {
e.printStackTrace();
}
其他回答
我还想保存一张图片。但是我的问题(?)是我想从我画的位图中保存它。
我是这样写的:
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.save_sign:
myView.save();
break;
}
return false;
}
public void save() {
String filename;
Date date = new Date(0);
SimpleDateFormat sdf = new SimpleDateFormat ("yyyyMMddHHmmss");
filename = sdf.format(date);
try{
String path = Environment.getExternalStorageDirectory().toString();
OutputStream fOut = null;
File file = new File(path, "/DCIM/Signatures/"+filename+".jpg");
fOut = new FileOutputStream(file);
mBitmap.compress(Bitmap.CompressFormat.JPEG, 85, fOut);
fOut.flush();
fOut.close();
MediaStore.Images.Media.insertImage(getContentResolver()
,file.getAbsolutePath(),file.getName(),file.getName());
}catch (Exception e) {
e.printStackTrace();
}
}
为什么不调用Bitmap.compress方法100(这听起来像是无损的)?
try (FileOutputStream out = new FileOutputStream(filename)) {
bmp.compress(Bitmap.CompressFormat.PNG, 100, out); // bmp is your Bitmap instance
// PNG is a lossless format, the compression factor (100) is ignored
} catch (IOException e) {
e.printStackTrace();
}
Bitmap bbicon;
bbicon=BitmapFactory.decodeResource(getResources(),R.drawable.bannerd10);
//ByteArrayOutputStream baosicon = new ByteArrayOutputStream();
//bbicon.compress(Bitmap.CompressFormat.PNG,0, baosicon);
//bicon=baosicon.toByteArray();
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
OutputStream outStream = null;
File file = new File(extStorageDirectory, "er.PNG");
try {
outStream = new FileOutputStream(file);
bbicon.compress(Bitmap.CompressFormat.PNG, 100, outStream);
outStream.flush();
outStream.close();
} catch(Exception e) {
}
保存位图到您的图库没有压缩。
private File saveBitMap(Context context, Bitmap Final_bitmap) {
File pictureFileDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "Your Folder Name");
if (!pictureFileDir.exists()) {
boolean isDirectoryCreated = pictureFileDir.mkdirs();
if (!isDirectoryCreated)
Log.i("TAG", "Can't create directory to save the image");
return null;
}
String filename = pictureFileDir.getPath() + File.separator + System.currentTimeMillis() + ".jpg";
File pictureFile = new File(filename);
try {
pictureFile.createNewFile();
FileOutputStream oStream = new FileOutputStream(pictureFile);
Final_bitmap.compress(Bitmap.CompressFormat.PNG, 100, oStream);
oStream.flush();
oStream.close();
Toast.makeText(Full_Screen_Activity.this, "Save Image Successfully..", Toast.LENGTH_SHORT).show();
} catch (IOException e) {
e.printStackTrace();
Log.i("TAG", "There was an issue saving the image.");
}
scanGallery(context, pictureFile.getAbsolutePath());
return pictureFile;
}
private void scanGallery(Context cntx, String path) {
try {
MediaScannerConnection.scanFile(cntx, new String[]{path}, null, new MediaScannerConnection.OnScanCompletedListener() {
public void onScanCompleted(String path, Uri uri) {
Toast.makeText(Full_Screen_Activity.this, "Save Image Successfully..", Toast.LENGTH_SHORT).show();
}
});
} catch (Exception e) {
e.printStackTrace();
Log.i("TAG", "There was an issue scanning gallery.");
}
}
