將pdf文件從資產復制到SD卡

Question

在我的資產文件夾中，我有一個名為lecture.pdf的pdf文件。 我試圖將此文件從資產復制到SD卡，以便從我的應用程序中讀取pdf，但該文件無法在SD卡上寫入。 誰能告訴我我做錯了什么。 這是寫入sd卡目錄的代碼

公共類XAclass擴展Activity {

WebView web;


@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.large);

   new Asyntasking();

    Intent intent = new Intent(getParent(), MyPdfViewerActivity.class);
    intent.putExtra(PdfViewerActivity.EXTRA_PDFFILENAME,
            "mnt/sdcard/mylecture/lecture.pdf");

    startActivity(intent);


}



private class Asyntasking extends AsyncTask<Void,Void,Void>
{
 private void CopyAssets() {
        AssetManager assetManager = getAssets();
        String[] files = {};
        try {
            files = assetManager.list("lecture.pdf");
        } catch (IOException e) {
            Log.e("tag", e.getMessage());
        }

        for(String filename : files) {
            System.out.println("File name => "+filename);
            InputStream in= null;

            OutputStream out = null;
            try {
              in = assetManager.open("/mnt/sdcard/mylecture/"+filename);   // if files resides inside the "Files" directory itself
              out = new FileOutputStream("/mnt/sdcard/mylecture/"+filename);
              copyFile(in, out);
              in.close();
              in = null;
              out.flush();
              out.close();
              out = null;
            } catch(Exception e) { 
                Log.e("tag", e.getMessage());
            }
        }
    }
    private void copyFile(InputStream in, OutputStream out) throws IOException {
        byte[] buffer = new byte[1024];
        int read;
        while((read = in.read(buffer)) != -1){
          out.write(buffer, 0, read);
        }
    }

@Override protected Void doInBackground（Void ... params）{// TODO自動生成的方法stub CopyAssets（）; return null; }

}

}

Answer 1

試試這段代碼

private class Asyntasking extends AsyncTask<Void,Void,Void>
    {
     private void CopyAssets() {
            AssetManager assetManager = getAssets();
            String[] files = {};
            try {
                files = assetManager.list("Files");
            } catch (IOException e) {
                Log.e("tag", e.getMessage());
            }

            for(String filename : files) {
                System.out.println("File name => "+filename);
                InputStream in= null;

                OutputStream out = null;
                try {
                  in = assetManager.open("Files/"+filename);   // if files resides inside the "Files" directory itself
                  out = new FileOutputStream(exportDirectory+filename);
                  copyFile(in, out);
                  in.close();
                  in = null;
                  out.flush();
                  out.close();
                  out = null;
                } catch(Exception e) { 
                    Log.e("tag", e.getMessage());
                }
            }
        }
        private void copyFile(InputStream in, OutputStream out) throws IOException {
            byte[] buffer = new byte[1024];
            int read;
            while((read = in.read(buffer)) != -1){
              out.write(buffer, 0, read);
            }
        }





@Override
    protected Void doInBackground(Void... params) {
        // TODO Auto-generated method stub
        CopyAssets();
                return null;
    }

Answer 2

要在外部存儲中寫入數據，我們必須在AndroidManifest.xml中授予權限。

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

現在你更新了logcat你可以使用AsyncTask或Handler解決這個錯誤。