下载pdf文件并保存到SD卡

我想下载并保存pdf文件到内部存储。 这是我正在使用的代码：

我从其他类调用我的方法：

new Thread(new Runnable() { public void run() { new Main().downloadPdfContent("http://people.opera.com/howcome/2005/ala/sample.pdf"); } }).start(); 

方法如下：

 public void downloadPdfContent(String urlToDownload){ URLConnection urlConnection = null; try{ URL url = new URL(urlToDownload); //Opening connection of currrent url urlConnection = url.openConnection(); urlConnection.connect(); //int lenghtOfFile = urlConnection.getContentLength(); String PATH = Environment.getExternalStorageDirectory() + "/1/"; File file = new File(PATH); file.mkdirs(); File outputFile = new File(file, "test.pdf"); FileOutputStream fos = new FileOutputStream(outputFile); InputStream is = url.openStream(); byte[] buffer = new byte[1024]; int len1 = 0; while ((len1 = is.read(buffer)) != -1) { fos.write(buffer, 0, len1); } fos.close(); is.close(); System.out.println("--pdf downloaded--ok--"+urlToDownload); }catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } 

我在网上找到了pdf的链接： http ： //people.opera.com/howcome/2005/ala/sample.pdf

但是我在这一行得到例外：

urlConnection.connect（）;

例外： java.net.UnknownHostException：people.opera.com

我无法弄清楚出了什么问题。 也许有人可以看一看。

谢谢。

Answer 1

放

在你的AndroidManifest.xml中

Answer 2

请遵循以下步骤：

1）声明文件名

 String fileName; //for image fileName = "matchfine1.png"; //for pdf fileName = "samplepdf.pdf"; 

2）调用下载过程的调用方法。

 startDownload(fileName); 

3）定义startDownload方法：

 //for download file start private void startDownload(String filename) { String filedowname = filename; //for image String url = "http://sofzh.miximages.com/java/298125983_0e4bf66782_b.jpg"; //for pdf String url = "http://people.opera.com/howcome/2005/ala/sample.pdf"; new DownloadFileAsync().execute(url,filedowname); } 

4）对于自动加载progressBar：

 @Override protected Dialog onCreateDialog(int id) { switch (id) { case DIALOG_DOWNLOAD_PROGRESS: mProgressDialog = new ProgressDialog(this); mProgressDialog.setMessage("Downloading file.."); mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); mProgressDialog.setCancelable(false); mProgressDialog.show(); return mProgressDialog; default: return null; } } 

5）定义扩展AsyncTask的下载过程

 class DownloadFileAsync extends AsyncTask { @Override protected void onPreExecute() { super.onPreExecute(); showDialog(DIALOG_DOWNLOAD_PROGRESS); } @Override protected String doInBackground(final String... aurl) { try { File root = android.os.Environment.getExternalStorageDirectory(); File dir = new File (root.getAbsolutePath() + "/Your_file_save_path/"); if(dir.exists()==false) { dir.mkdirs(); } URL url = new URL(aurl[0]); String filename = aurl[1]; URLConnection conexion = url.openConnection(); conexion.connect(); int lenghtOfFile = conexion.getContentLength(); Log.d("ANDRO_ASYNC", "Lenght of file: " + lenghtOfFile); InputStream input = new BufferedInputStream(url.openStream()); OutputStream output = new FileOutputStream(dir+"/"+filename); byte data[] = new byte[1024]; long total = 0; int count; while ((count = input.read(data)) != -1) { total += count; publishProgress(""+(int)((total*100)/lenghtOfFile)); output.write(data, 0, count); } output.flush(); output.close(); input.close(); } catch (Exception e) {} return null; } protected void onProgressUpdate(String... progress) { Log.d("ANDRO_ASYNC", progress[0]); mProgressDialog.setProgress(Integer.parseInt(progress[0])); } @Override protected void onPostExecute(String unused) { dismissDialog(DIALOG_DOWNLOAD_PROGRESS); } } //for download file end 

6）用dir中的文件路径替换“Your_file_save_path”。 然后下载并检查指定的位置。

Answer 3

我使用了相同的代码并得到了Network.onThreadException错误 。

但是在我的oncreate（）方法中使用这段代码之后，我就能够解决这个问题了。

 if (android.os.Build.VERSION.SDK_INT > 9) { StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); StrictMode.setThreadPolicy(policy); }