为什么不调用Bitmap.compress方法100(这听起来像是无损的)?

我发现发送PNG和透明度的方式。

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")));

下面是保存位图到文件的示例代码:

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;
}

现在调用这个函数将位图保存到内部内存中。

文件newfile = savebitmap(位图);

我希望它能帮助你。 快乐编码生活。

您应该使用Bitmap.compress()方法将位图保存为文件。它将压缩(如果所使用的格式允许的话)您的图片并将其推入OutputStream。

下面是一个通过getImageBitmap(myurl)获得的位图实例，可以压缩为JPEG，压缩率为85%:

// 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());

一些新设备不保存位图，所以我解释了一点。

请确保您在下面添加了权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

并在XML文件夹名为provider_paths.xml下创建一个XML文件

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path
        name="external_files"
        path="." />
</paths>

and in AndroidManifest under <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> then simply call 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(); } where 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()); } } and other methods 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; } and 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); }

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();
}