将图像保存在外部存储中通过使用来自 Url 的 Picasso ，如何下载图像并在 imageview 中显示它

Question

请使用此代码通过使用 Url 将图像保存在外部存储中

//Please Put your Image url In $url

Picasso.get().load($url).into(object : Target{
                            override fun onPrepareLoad(placeHolderDrawable: Drawable?) {

                            }

                            override fun onBitmapFailed(e: java.lang.Exception?, errorDrawable: Drawable?) {
                                TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
                            }

                            override fun onBitmapLoaded(bitmap: Bitmap?, from: Picasso.LoadedFrom?) {
                                try {
                                    val root = Environment.getExternalStorageDirectory().toString()
                                    var myDir = File("$root")

                                    if (!myDir.exists()) {
                                        myDir.mkdirs()
                                    }
                                    val name = Date().toString() + ".jpg"
                                    myDir = File(myDir, name)
                                    val out = FileOutputStream(myDir)
                                    bitmap?.compress(Bitmap.CompressFormat.JPEG, 90, out)

                                    out.flush()
                                    out.close()
                                } catch (e: Exception) {
                                    // some action
                                }
                            }
                        })

和图像将保存在 sdcard 中。

Answer 1

使用此方法下载内存中的图像

 // DownloadImage AsyncTask
    private class DownloadImage extends AsyncTask<String, Void, Bitmap> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

        }

        @Override
        protected Bitmap doInBackground(String... URL) {

            String imageURL = URL[0];

            Bitmap bitmap = null;
            try {
                // Download Image from URL
                InputStream input = new java.net.URL(imageURL).openStream();
                // Decode Bitmap
                bitmap = BitmapFactory.decodeStream(input);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Bitmap result) {

                if (result != null) {
                    File destination = new File(getActivity().getCacheDir(),
                            "profile" + ".jpg");
                    try {
                        destination.createNewFile();
                        ByteArrayOutputStream bos = new ByteArrayOutputStream();
                        result.compress(Bitmap.CompressFormat.PNG, 0 /*ignored for PNG*/, bos);
                        byte[] bitmapdata = bos.toByteArray();

                        FileOutputStream fos = new FileOutputStream(destination);
                        fos.write(bitmapdata);
                        fos.flush();
                        fos.close();
                        selectedFile = destination;
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }


            
        }
    }

并像这样调用这个方法

Picasso.get().load(response.body()?.url).into(object : Target{
                            override fun onPrepareLoad(placeHolderDrawable: Drawable?) {

                            }

                            override fun onBitmapFailed(e: java.lang.Exception?, errorDrawable: Drawable?) {
                               
                            }

                            override fun onBitmapLoaded(bitmap: Bitmap?, from: Picasso.LoadedFrom?) {
                               new DownloadImage().execute("url_here);
                            }
                        })

注意：- 复制此代码并粘贴， Kotlin转换器会自动将其转换为Kotlin

Answer 2

1- 添加到 AndroidManifest.xml

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

2- 使用此方法从 Url 使用 Picasso 下载图像：

    private static void SaveImage(final Context context, final String MyUrl){
    final ProgressDialog progress = new ProgressDialog(context);
    class SaveThisImage extends AsyncTask<Void, Void, Void> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            progress.setTitle("Processing");
            progress.setMessage("Please Wait...");
            progress.setCancelable(false);
            progress.show();
        }
        @Override
        protected Void doInBackground(Void... arg0) {
            try{

                File sdCard = Environment.getExternalStorageDirectory();
                @SuppressLint("DefaultLocale") String fileName = String.format("%d.jpg", System.currentTimeMillis());
                File dir = new File(sdCard.getAbsolutePath() + "/savedImageName");
                dir.mkdirs();
                final File myImageFile = new File(dir, fileName); // Create image file
                FileOutputStream fos = null;
                try {
                    fos = new FileOutputStream(myImageFile);
                    Bitmap bitmap = Picasso.get().load(MyUrl).get();
                    bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);

                    Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
                    intent.setData(Uri.fromFile(myImageFile));
                    context.sendBroadcast(intent);
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    try {
                        fos.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }catch (Exception e){
            }
            return null;
        }
        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            if(progress.isShowing()){
                progress.dismiss();
            }
            Toast.makeText(context, "Saved", Toast.LENGTH_SHORT).show();
        }
    }
    SaveThisImage shareimg = new SaveThisImage();
    shareimg.execute();
}

3-如何使用，只需调用：

SaveImage(context, "Image URL");