如何从 url 保存图像？

Question

我正在使用带有外部图像 URL 的 setImageBitmap 设置 ImageView。我想保存图像，以便以后即使没有互联网连接也可以使用。我可以在哪里以及如何保存它？

Answer 1

URL imageurl = new URL("http://mysite.com/me.jpg"); 
Bitmap bitmap = BitmapFactory.decodeStream(imageurl.openConnection().getInputStream()); 

此代码将帮助您从图像 url 生成位图。

这个question回答了第二部分。

Answer 2

您必须将其保存在 SD 卡或包数据中，因为在运行时您只能访问这些。这是一个很好的例子

URL url = new URL ("file://some/path/anImage.png");
InputStream input = url.openStream();
try {
//The sdcard directory e.g. '/sdcard' can be used directly, or 
//more safely abstracted with getExternalStorageDirectory()
File storagePath = Environment.getExternalStorageDirectory();
OutputStream output = new FileOutputStream (storagePath + "/myImage.png");
try {
    byte[] buffer = new byte[aReasonableSize];
    int bytesRead = 0;
    while ((bytesRead = input.read(buffer, 0, buffer.length)) >= 0) {
        output.write(buffer, 0, bytesRead);
    }
} finally {
    output.close();
}
} finally {
input.close();
}

来源：How do I transfer an image from its URL to the SD card?

Answer 3

如果您在应用中使用 Kotlin 和 Glide，那么这适合您：

Glide.with(this)
                .asBitmap()
                .load(imageURL)
                .into(object : SimpleTarget<Bitmap>(1920, 1080) {
                    override fun onResourceReady(bitmap: Bitmap, transition: Transition<in Bitmap>?) {
                        saveImage(bitmap)
                    }
                })

这就是那个功能

internal fun saveImage(image: Bitmap) {
    val savedImagePath: String

    val imageFileName = System.currentTimeMillis().toString() + ".jpg"
    val storageDir = File(Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES).toString() + "/Folder Name")
    var success = true
    if (!storageDir.exists()) {
        success = storageDir.mkdirs()
    }
    if (success) {
        val imageFile = File(storageDir, imageFileName)
        savedImagePath = imageFile.absolutePath
        try {
            val fOut = FileOutputStream(imageFile)
            image.compress(Bitmap.CompressFormat.JPEG, 100, fOut)
            fOut.close()
        } catch (e: Exception) {
            e.printStackTrace()
        }

        galleryAddPic(savedImagePath)
    }
}


private fun galleryAddPic(imagePath: String) {
    val mediaScanIntent = Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE)
    val f = File(imagePath)
    val contentUri = FileProvider.getUriForFile(applicationContext, packageName, f)
    mediaScanIntent.data = contentUri
    sendBroadcast(mediaScanIntent)
}

galleryAddPic() 用于查看手机图库中的图片。

注意：现在如果您遇到文件 uri 异常，那么 this 可以帮助您。

Answer 4

您可以将图像保存在 sdcard 中，以后无需互联网即可使用该图像。

see this tutorial 将展示如何存储图像并再次读取它。

希望这对你有帮助......！

Answer 5

也许有一天它会帮助像我这样的人

 new SaveImage().execute(mViewPager.getCurrentItem());//calling function

private void saveImage(int currentItem) {
    String stringUrl = Site.BASE_URL + "socialengine/" + allImages.get(currentItem).getMaster();
    Utils.debugger(TAG, stringUrl);

    HttpURLConnection urlConnection = null;
    try {
        URL url = new URL(stringUrl);
        urlConnection = (HttpURLConnection) url.openConnection();
        urlConnection.setRequestMethod("GET");
        urlConnection.setDoOutput(true);
        urlConnection.connect();
        File sdCardRoot = Environment.getExternalStorageDirectory().getAbsoluteFile();

        String fileName = stringUrl.substring(stringUrl.lastIndexOf('/') + 1, stringUrl.length());
        String fileNameWithoutExtn = fileName.substring(0, fileName.lastIndexOf('.'));

        File imgFile = new File(sdCardRoot, "IMG" + System.currentTimeMillis() / 100 + fileName);
        if (!sdCardRoot.exists()) {
            imgFile.createNewFile();
        }

        InputStream inputStream = urlConnection.getInputStream();
        int totalSize = urlConnection.getContentLength();
        FileOutputStream outPut = new FileOutputStream(imgFile);

        int downloadedSize = 0;
        byte[] buffer = new byte[2024];
        int bufferLength = 0;
        while ((bufferLength = inputStream.read(buffer)) > 0) {
            outPut.write(buffer, 0, bufferLength);
            downloadedSize += bufferLength;
            Utils.debugger("Progress:", "downloadedSize:" + Math.abs(downloadedSize*100/totalSize));
        }
        outPut.close();
        //if (downloadedSize == totalSize);
            //Toast.makeText(context, "Downloaded" + imgFile.getPath(), Toast.LENGTH_LONG).show();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

 private class SaveImage extends AsyncTask<Integer, Void, String> {

    @Override
    protected String doInBackground(Integer... strings) {
        saveImage(strings[0]);
        return "saved";
    }

    @Override
    protected void onPostExecute(String s) {
        Toast.makeText(context, "" + s, Toast.LENGTH_SHORT).show();
    }
}