Android - 將URL中的圖像保存到SD卡上

Question

我想將圖像從URL保存到SD卡（以備將來使用），然后從SD卡加載該圖像，將其用作Google地圖的可繪制疊加層。

這是函數的保存部分：

//SAVE TO FILE

String filepath = Environment.getExternalStorageDirectory().getAbsolutePath(); 
String extraPath = "/Map-"+RowNumber+"-"+ColNumber+".png";
filepath += extraPath;

FileOutputStream fos = null;
fos = new FileOutputStream(filepath); 

bmImg.compress(CompressFormat.PNG, 75, fos);

//LOAD IMAGE FROM FILE
Drawable d = Drawable.createFromPath(filepath);
return d;

圖像以succuessfully方式保存到SD卡，但在到達createFromPath()行時失敗。 我不明白為什么它會保存到那個目的地但不加載它....

Answer 1

試試這個代碼。它有效......

try
{   
  URL url = new URL("Enter the URL to be downloaded");
  HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
  urlConnection.setRequestMethod("GET");
  urlConnection.setDoOutput(true);                   
  urlConnection.connect();                  
  File SDCardRoot = Environment.getExternalStorageDirectory().getAbsoluteFile();
  String filename="downloadedFile.png";   
  Log.i("Local filename:",""+filename);
  File file = new File(SDCardRoot,filename);
  if(file.createNewFile())
  {
    file.createNewFile();
  }                 
  FileOutputStream fileOutput = new FileOutputStream(file);
  InputStream inputStream = urlConnection.getInputStream();
  int totalSize = urlConnection.getContentLength();
  int downloadedSize = 0;   
  byte[] buffer = new byte[1024];
  int bufferLength = 0;
  while ( (bufferLength = inputStream.read(buffer)) > 0 ) 
  {                 
    fileOutput.write(buffer, 0, bufferLength);                  
    downloadedSize += bufferLength;                 
    Log.i("Progress:","downloadedSize:"+downloadedSize+"totalSize:"+ totalSize) ;
  }             
  fileOutput.close();
  if(downloadedSize==totalSize) filepath=file.getPath();    
} 
catch (MalformedURLException e) 
{
  e.printStackTrace();
} 
catch (IOException e)
{
  filepath=null;
  e.printStackTrace();
}
Log.i("filepath:"," "+filepath) ;
return filepath;

Answer 2

DownloadManager為您完成所有這些工作。

public void downloadFile(String uRl) {
    File direct = new File(Environment.getExternalStorageDirectory()
            + "/AnhsirkDasarp");

    if (!direct.exists()) {
        direct.mkdirs();
    }

    DownloadManager mgr = (DownloadManager) getActivity().getSystemService(Context.DOWNLOAD_SERVICE);

    Uri downloadUri = Uri.parse(uRl);
    DownloadManager.Request request = new DownloadManager.Request(
            downloadUri);

    request.setAllowedNetworkTypes(
            DownloadManager.Request.NETWORK_WIFI
                    | DownloadManager.Request.NETWORK_MOBILE)
            .setAllowedOverRoaming(false).setTitle("Demo")
            .setDescription("Something useful. No, really.")
            .setDestinationInExternalPublicDir("/AnhsirkDasarpFiles", "fileName.jpg");

    mgr.enqueue(request);

    // Open Download Manager to view File progress
    Toast.makeText(getActivity(), "Downloading...",Toast.LENGTH_LONG).show();
    startActivity(Intent(DownloadManager.ACTION_VIEW_DOWNLOADS));

}

Answer 3

嘗試使用此代碼將圖像從URL保存到SDCard。

URL url = new URL ("file://some/path/anImage.png"); 
InputStream input = url.openStream(); 
try {     
    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(); 
}

如果要在SD卡上創建子目錄，請使用：

File storagePath = new File(Environment.getExternalStorageDirectory(),"Wallpaper");
storagePath.mkdirs();

創建子目錄“/ sdcard / Wallpaper /”。

希望它會對你有所幫助。

請享用。 :)

Answer 4

我也遇到了同樣的問題並用此解決了我的問題。 試試這個

private class ImageDownloadAndSave extends AsyncTask<String, Void, Bitmap>
        {
            @Override
            protected Bitmap doInBackground(String... arg0) 
            {           
                downloadImagesToSdCard("","");
                return null;
            }

               private void downloadImagesToSdCard(String downloadUrl,String imageName)
                {
                    try
                    {
                        URL url = new URL(img_URL); 
                        /* making a directory in sdcard */
                        String sdCard=Environment.getExternalStorageDirectory().toString();     
                        File myDir = new File(sdCard,"test.jpg");

                        /*  if specified not exist create new */
                        if(!myDir.exists())
                        {
                            myDir.mkdir();
                            Log.v("", "inside mkdir");
                        }

                        /* checks the file and if it already exist delete */
                        String fname = imageName;
                        File file = new File (myDir, fname);
                        if (file.exists ()) 
                            file.delete (); 

                             /* Open a connection */
                        URLConnection ucon = url.openConnection();
                        InputStream inputStream = null;
                        HttpURLConnection httpConn = (HttpURLConnection)ucon;
                        httpConn.setRequestMethod("GET");
                        httpConn.connect();

                          if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) 
                          {
                           inputStream = httpConn.getInputStream();
                          }

                            FileOutputStream fos = new FileOutputStream(file);  
                int totalSize = httpConn.getContentLength();
                        int downloadedSize = 0;   
                        byte[] buffer = new byte[1024];
                        int bufferLength = 0;
                        while ( (bufferLength = inputStream.read(buffer)) >0 ) 
                        {                 
                          fos.write(buffer, 0, bufferLength);                  
                          downloadedSize += bufferLength;                 
                          Log.i("Progress:","downloadedSize:"+downloadedSize+"totalSize:"+ totalSize) ;
                        }   

                            fos.close();
                            Log.d("test", "Image Saved in sdcard..");                      
                    }
                    catch(IOException io)
                    {                  
                         io.printStackTrace();
                    }
                    catch(Exception e)
                    {                     
                        e.printStackTrace();
                    }
                }           
        } 

在AsyncTask中聲明您的網絡操作，因為它會將其作為后台任務加載。 不要在主線程上加載網絡操作。 在按鈕單擊或內容視圖中調用此類之后

 new ImageDownloadAndSave().execute("");

並且不要忘記將nework權限添加為：

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

希望這可以幫助某人:-)

Answer 5

試試這個......完成任務的簡單方法。

Picasso.with(getActivity())
                .load(url)
                .into(new Target() {
                          @Override
                          public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                              try {
                                  String root = Environment.getExternalStorageDirectory().toString();
                                  File myDir = new File(root + "/yourDirectory");

                                  if (!myDir.exists()) {
                                      myDir.mkdirs();
                                  }

                                  String name = new Date().toString() + ".jpg";
                                  myDir = new File(myDir, name);
                                  FileOutputStream out = new FileOutputStream(myDir);
                                  bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);

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

                          @Override
                          public void onBitmapFailed(Drawable errorDrawable) {
                          }

                          @Override
                          public void onPrepareLoad(Drawable placeHolderDrawable) {
                          }
                      }
                );

Answer 6

我相信這是失敗的，因為你正在將位圖的壓縮版本寫入輸出流，應該使用BitmapFactory.decodeStream()加載。 快速瀏覽一下這方面的文檔。

如果你需要一個Drawable （ decodeStream()返回一個Bitmap ），只需調用Drawable d = new BitmapDrawable(bitmap) 。

Answer 7

試試這個代碼......工作正常

public static Bitmap loadImageFromUrl(String url) {
            URL m;
            InputStream i = null;
            BufferedInputStream bis = null;
            ByteArrayOutputStream out =null;
            try {
                m = new URL(url);
                i = (InputStream) m.getContent();
                bis = new BufferedInputStream(i,1024 * 8);
                out = new ByteArrayOutputStream();
                int len=0;
                byte[] buffer = new byte[1024];
                while((len = bis.read(buffer)) != -1){
                    out.write(buffer, 0, len);
                }
                out.close();
                bis.close();
            } catch (MalformedURLException e1) {
                e1.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            byte[] data = out.toByteArray();
            Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
            //Drawable d = Drawable.createFromStream(i, "src");
            return bitmap;
        }

並將位圖保存到目錄中

ByteArrayOutputStream bytes = new ByteArrayOutputStream();
_bitmap.compress(Bitmap.CompressFormat.JPEG, 40, bytes);

//you can create a new file name "test.jpg" in sdcard folder.
File f = new File(Environment.getExternalStorageDirectory()
                        + File.separator + "test.jpg")
f.createNewFile();
//write the bytes in file
FileOutputStream fo = new FileOutputStream(f);
fo.write(bytes.toByteArray());

// remember close de FileOutput
fo.close();

並且不要忘記添加對清單的權限

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