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

为视频创建一个视频缩略图。如果视频损坏或格式不支持,它可能返回null。

private void makeVideoPreview() {
    Bitmap thumbnail = ThumbnailUtils.createVideoThumbnail(videoAbsolutePath, MediaStore.Images.Thumbnails.MINI_KIND);
    saveImage(thumbnail);
}

使用以下代码将位图保存在sdcard中

商店形象

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());
    }  
}

获取图像存储路径

/** 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;
} 

其他回答

有些格式,比如无损的PNG,会忽略质量设置。

嘿,把名字给。bmp

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**")

这将听起来,IM只是愚弄周围,但尝试一下,它会被保存在bmp的foramt..干杯

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());