android - 将 pdf 文件从 Assets 复制到 SD 卡

Question

在我的 Assets 文件夹中，我有一个名为 lecture.pdf 的 pdf 文件。我正在尝试将此文件从 Assets 复制到 SD 卡，以便从我的应用程序读取 pdf，但该文件无法写入 SD 卡。有人可以告诉我我做错了什么。下面是写入sd卡目录的代码

公共(public)类 XAclass 扩展 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);
        }
    }

@覆盖 protected Void doInBackground(Void... params) { //TODO 自动生成的方法 stub 复制 Assets ()； 返回空值；

}

Answer 1

试试这段代码

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;
    }