题
我正在开发一个功能,从网络服务器下载图像,将其显示在屏幕上,如果用户希望保留图像,请将其保存在 SD 卡上的某个文件夹中。有没有一种简单的方法可以获取位图并将其保存到 SD 卡中我选择的文件夹中?
我的问题是我可以下载图像,将其作为位图显示在屏幕上。我能够找到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。我不确定如何从位图转换(如果这是正确的方法)到字节数组,因此我可以使用 FileOutputStream 来写入数据。
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。
解决方案
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();
}
其他提示
您应该使用Bitmap.compress()
方法将位图保存为一个文件。这将压缩(如果使用的格式允许)的图片,并将其推入的OutputStream。
下面是通过getImageBitmap(myurl)
获得的Bitmap实例,可以为85%的压缩率来压缩为JPEG的一个示例:
// Assume block needs to be inside a Try/Catch block.
String path = Environment.getExternalStorageDirectory().toString();
OutputStream fOut = null;
Integer counter = 0;
File file = new File(path, "FitnessGirl"+counter+".jpg"); // the File to save , append increasing numeric counter to prevent files from getting overwritten.
fOut = new FileOutputStream(file);
Bitmap pictureBitmap = getImageBitmap(myurl); // obtaining the Bitmap
pictureBitmap.compress(Bitmap.CompressFormat.JPEG, 85, fOut); // saving the Bitmap to a file compressed as a JPEG with 85% compression rate
fOut.flush(); // Not really required
fOut.close(); // do not forget to close the stream
MediaStore.Images.Media.insertImage(getContentResolver(),file.getAbsolutePath(),file.getName(),file.getName());
outStream = new FileOutputStream(file);
将抛出异常未经许可在AndroidManifest.xml(至少在OS2.2):
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
内部onActivityResult
:
String filename = "pippo.png";
File sd = Environment.getExternalStorageDirectory();
File dest = new File(sd, filename);
Bitmap bitmap = (Bitmap)data.getExtras().get("data");
try {
FileOutputStream out = new FileOutputStream(dest);
bitmap.compress(Bitmap.CompressFormat.PNG, 90, out);
out.flush();
out.close();
} catch (Exception e) {
e.printStackTrace();
}
有的格式,比如PNG是无损的,将忽略质量设置。
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) {
}
下面是用于保存位图以文件的示例代码:
public static File savebitmap(Bitmap bmp) throws IOException {
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.JPEG, 60, bytes);
File f = new File(Environment.getExternalStorageDirectory()
+ File.separator + "testimage.jpg");
f.createNewFile();
FileOutputStream fo = new FileOutputStream(f);
fo.write(bytes.toByteArray());
fo.close();
return f;
}
现在调用该函数将位图保存到内部存储器中。
File newfile = savebitmap(bitmap)
;
我希望这会帮助你。 快乐codeing生活。
为什么不叫100的Bitmap.compress
方法(这听起来就像是无损的)?
我也想保存图片。但我的问题(?)是,我希望把它从香港专业教育学院drawed位图保存。
我制成这样的:
@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();
}
}
我发现的方法来发送PNG和透明度。
String file_path = Environment.getExternalStorageDirectory().getAbsolutePath() +
"/CustomDir";
File dir = new File(file_path);
if(!dir.exists())
dir.mkdirs();
String format = new SimpleDateFormat("yyyyMMddHHmmss",
java.util.Locale.getDefault()).format(new Date());
File file = new File(dir, format + ".png");
FileOutputStream fOut;
try {
fOut = new FileOutputStream(file);
yourbitmap.compress(Bitmap.CompressFormat.PNG, 85, fOut);
fOut.flush();
fOut.close();
} catch (Exception e) {
e.printStackTrace();
}
Uri uri = Uri.fromFile(file);
Intent intent = new Intent(android.content.Intent.ACTION_SEND);
intent.setType("image/*");
intent.putExtra(android.content.Intent.EXTRA_SUBJECT, "");
intent.putExtra(android.content.Intent.EXTRA_TEXT, "");
intent.putExtra(Intent.EXTRA_STREAM, uri);
startActivity(Intent.createChooser(intent,"Sharing something")));
创建视频的视频的缩略图。如果视频被损坏或不支持的格式可能返回null。
private void makeVideoPreview() {
Bitmap thumbnail = ThumbnailUtils.createVideoThumbnail(videoAbsolutePath, MediaStore.Images.Thumbnails.MINI_KIND);
saveImage(thumbnail);
}
要保存的位图中的SD卡使用以下代码
商品图片
private void storeImage(Bitmap image) {
File pictureFile = getOutputMediaFile();
if (pictureFile == null) {
Log.d(TAG,
"Error creating media file, check storage permissions: ");// e.getMessage());
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
image.compress(Bitmap.CompressFormat.PNG, 90, fos);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
要获取图像存储路径强>
/** Create a File for saving an image or video */
private File getOutputMediaFile(){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStorageDirectory()
+ "/Android/data/"
+ getApplicationContext().getPackageName()
+ "/Files");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("ddMMyyyy_HHmm").format(new Date());
File mediaFile;
String mImageName="MI_"+ timeStamp +".jpg";
mediaFile = new File(mediaStorageDir.getPath() + File.separator + mImageName);
return mediaFile;
}
嘿只是给名称为 .BMP 强>
这样做:
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
_bitmapScaled.compress(Bitmap.CompressFormat.PNG, 40, bytes);
//you can create a new file name "test.BMP" in sdcard folder.
File f = new File(Environment.getExternalStorageDirectory()
+ File.separator + "**test.bmp**")
这将声音,我只是打打闹闹,但试一次,它会得到保存为BMP foramt..Cheers
请确保您拨打bitmap.compress
之前创建的目录:
new File(FileName.substring(0,FileName.lastIndexOf("/"))).mkdirs();
4.4的Android奇巧后,和作为2017份额的Android 4.4且小于约20%和下降,这是不可能用File
类和getExternalStorageDirectory()
方法保存到SD卡。此方法返回设备内部存储器和图像保存可见每一个应用程序。您还可以将图像保存唯一的民营你的应用程序,并在用户与openFileOutput()
方法删除你的应用程序被删除。
与Android 6.0开始,你可以格式化你的SD卡作为内部存储器,但只有私有到您的设备。(如果格式化SD汽车作为内部存储器,只有你的设备可以访问或看到它的内容),您可以保存到使用SD卡等的答案,但如果你想使用可移动SD卡,你应该阅读我的回答如下。
您应该使用存储访问架构,以获得URI到文件夹活动的onActivityResult
方法,通过获取用户选择的文件夹,并添加retreive persistiable权限能够访问文件夹的用户重启设备后。
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
// selectDirectory() invoked
if (requestCode == REQUEST_FOLDER_ACCESS) {
if (data.getData() != null) {
Uri treeUri = data.getData();
tvSAF.setText("Dir: " + data.getData().toString());
currentFolder = treeUri.toString();
saveCurrentFolderToPrefs();
// grantUriPermission(getPackageName(), treeUri,
// Intent.FLAG_GRANT_READ_URI_PERMISSION |
// Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
final int takeFlags = data.getFlags()
& (Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
// Check for the freshest data.
getContentResolver().takePersistableUriPermission(treeUri, takeFlags);
}
}
}
}
现在,救救文件夹共享偏好不问用户文件夹要保存的图像每次选择。
您应该使用DocumentFile
类来保存你的形象,不File
或ParcelFileDescriptor
,获取更多信息,您可以检查的用于保存图像SD卡compress(CompressFormat.JPEG, 100, out);
方法和DocumentFile
类这个线程。
您想要将位图保存到您选择的目录中。我制作了一个 ImageWorker 库,使用户能够加载、保存和转换位图/绘图/base64 图像。
最小 SDK - 14
先决条件
- 保存文件需要 WRITE_EXTERNAL_STORAGE 权限。
- 检索文件需要 READ_EXTERNAL_STORAGE 权限。
保存位图/Drawable/Base64
ImageWorker.to(context).
directory("ImageWorker").
subDirectory("SubDirectory").
setFileName("Image").
withExtension(Extension.PNG).
save(sourceBitmap,85)
加载位图
val bitmap: Bitmap? = ImageWorker.from(context).
directory("ImageWorker").
subDirectory("SubDirectory").
setFileName("Image").
withExtension(Extension.PNG).
load()
执行
添加依赖项
在项目级别 Gradle 中
allprojects {
repositories {
...
maven { url 'https://jitpack.io' }
}
}
在应用程序级别 Gradle 中
dependencies {
implementation 'com.github.1AboveAll:ImageWorker:0.51'
}
您可以阅读更多内容 https://github.com/1AboveAll/ImageWorker/blob/master/README.md
一些新的设备不保存位图,这样我解释多一点..
请确保您已添加的以下权限
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
和创建下
xml
文件夹名称一个XML文件的 provider_paths.xml 强>
<?xml version="1.0" encoding="utf-8"?>
<paths>
<external-path
name="external_files"
path="." />
</paths>
和在AndroidManifest下
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="${applicationId}.provider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/provider_paths"/>
</provider>
然后简单地调用saveBitmapFile(passYourBitmapHere)
public static void saveBitmapFile(Bitmap bitmap) throws IOException {
File mediaFile = getOutputMediaFile();
FileOutputStream fileOutputStream = new FileOutputStream(mediaFile);
bitmap.compress(Bitmap.CompressFormat.JPEG, getQualityNumber(bitmap), fileOutputStream);
fileOutputStream.flush();
fileOutputStream.close();
}
,其中
File getOutputMediaFile() {
File mediaStorageDir = new File(
Environment.getExternalStorageDirectory(),
"easyTouchPro");
if (mediaStorageDir.isDirectory()) {
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(Calendar.getInstance().getTime());
String mCurrentPath = mediaStorageDir.getPath() + File.separator
+ "IMG_" + timeStamp + ".jpg";
File mediaFile = new File(mCurrentPath);
return mediaFile;
} else { /// error handling for PIE devices..
mediaStorageDir.delete();
mediaStorageDir.mkdirs();
galleryAddPic(mediaStorageDir);
return (getOutputMediaFile());
}
}
和其它方法
public static int getQualityNumber(Bitmap bitmap) {
int size = bitmap.getByteCount();
int percentage = 0;
if (size > 500000 && size <= 800000) {
percentage = 15;
} else if (size > 800000 && size <= 1000000) {
percentage = 20;
} else if (size > 1000000 && size <= 1500000) {
percentage = 25;
} else if (size > 1500000 && size <= 2500000) {
percentage = 27;
} else if (size > 2500000 && size <= 3500000) {
percentage = 30;
} else if (size > 3500000 && size <= 4000000) {
percentage = 40;
} else if (size > 4000000 && size <= 5000000) {
percentage = 50;
} else if (size > 5000000) {
percentage = 75;
}
return percentage;
}
和
void galleryAddPic(File f) {
Intent mediaScanIntent = new Intent(
"android.intent.action.MEDIA_SCANNER_SCAN_FILE");
Uri contentUri = Uri.fromFile(f);
mediaScanIntent.setData(contentUri);
this.sendBroadcast(mediaScanIntent);
}
并不是一个真正的答案,但评论。我在Mac上运行模拟器环境,并获得了java.io.IOException异常:权限被拒绝 - 错误与此代码:
protected void onActivityResult(int requestCode, int resultCode, Intent imageReturnedIntent) {
Log.d("DEBUG", "onActivityResult called");
super.onActivityResult(requestCode, resultCode, imageReturnedIntent);
if(requestCode == 0 && resultCode == RESULT_OK) {
Log.d("DEBUG", "result is ok");
try{
Bitmap map = (Bitmap) imageReturnedIntent.getExtras().get("data");
File sd = new File(Environment.getExternalStorageDirectory(), "test.png");
sd.mkdirs();
sd.createNewFile();
FileOutputStream out = new FileOutputStream(sd);
map.compress(Bitmap.CompressFormat.PNG, 90, out);
out.flush();
out.close();
} catch(FileNotFoundException e){
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
我还增加了使用的许可android.permission.WRITE_EXTERNAL_STORAGE到清单文件(如其他人指出)。
保存位图到您的画廊没有压缩。
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.");
}
}
// | == |创建从位图PNG文件:
void devImjFylFnc(String pthAndFylTtlVar, Bitmap iptBmjVar)
{
try
{
FileOutputStream fylBytWrtrVar = new FileOutputStream(pthAndFylTtlVar);
iptBmjVar.compress(Bitmap.CompressFormat.PNG, 100, fylBytWrtrVar);
fylBytWrtrVar.close();
}
catch (Exception errVar) { errVar.printStackTrace(); }
}
// | == |从文件获取BIMAP:
Bitmap getBmjFrmFylFnc(String pthAndFylTtlVar)
{
return BitmapFactory.decodeFile(pthAndFylTtlVar);
}