Android - 将URL中的图像保存到SD卡上

时间:2011-02-02 13:40:56

标签: java android maps emulation

我想将图像从URL保存到SD卡(以备将来使用),然后从SD卡加载该图像,将其用作Google地图的可绘制叠加层。

以下是该功能的保存部分:

//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;

图像以可疑方式保存到SD卡,但在到达createFromPath()行时失败。我不明白为什么它会保存到该目的地,但不能从它加载.......

7 个答案:

答案 0 :(得分:28)

试试此代码。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;

答案 1 :(得分:25)

DownloadManager为您完成所有这些。

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));

}

答案 2 :(得分:6)

尝试使用此代码将图像从URL保存到SD卡。

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卡上创建子目录,请使用:

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

创建子目录“/ sdcard / Wallpaper /”。

希望它会对你有所帮助。

享受。 :)

答案 3 :(得分:3)

我也遇到了同样的问题并用此解决了我的问题。试试这个

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中声明您的网络操作,因为它会将其作为后台任务加载。不要在主线程上加载网络操作。 在按钮点击或内容视图中调用此类之后

 new ImageDownloadAndSave().execute("");

不要忘记将nework权限添加为:

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

希望这可以帮助某人: - )

答案 4 :(得分:1)

我认为它失败了,因为您正在将位图的压缩版本写入输出流,应该使用BitmapFactory.decodeStream()加载。在此文档上有一个quick look

如果您需要DrawabledecodeStream()返回Bitmap),只需致电Drawable d = new BitmapDrawable(bitmap)

答案 5 :(得分:1)

试试此代码..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;
        }

并将位图保存到目录

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();

并且不要忘记添加清单

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

答案 6 :(得分:1)

试试这个......完成任务的简单方法。

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) {
                          }
                      }
                );