PdfDocument generate PDF, always generates an empty file

Use PdfDocument generate PDF files, when the content changes, it will have an empty file, whether it is page.getCanvas () drawText ( "12345", 20, 50, paint).;

still is

view1.draw(canvas);

Code is as follows:
public void actionGenPdf (View View)
{
    // create a PDF text object
    PDFDocument Document PDFDocument new new = ();
    // create this page of information, the parameter indicates Builder width and height of the page, and which page

    PdfDocument. = new new PdfDocument.PageInfo.Builder PageInfo PageInfo (595, 843,1) .create ();

    // this page generating
    PdfDocument.Page page document.startPage = (PageInfo);

    // draw on this page, i.e. to the needed to view the page view of the canvas painting
    the Paint Paint new new = the Paint ();
    paint.setColor (as Color.BLACK.);
    paint.setTextSize (20 is);
    the canvas page.getCanvas = canvas ();

    / * for (int I 0 =; I <10; I ++) {
        String STMP = "12345";
        . page.getCanvas () drawText ( "12345", 20 is, 50, Paint);
        canvas.translate(0, 30);
    }*/
    TextView view1 = new TextView(this);//getContentView();
    view1.layout(0, 0, 200, 200);
    view1.setText("Hello");
    TextView view2 = new TextView(this);//getContentView();
    view2.layout(0, 0, 200, 200);
    String sTmp = "Good"+Integer.toString(10);
    final String ss = sTmp;
    view2.setText(ss);
    view1.draw(canvas);
    canvas.translate(0, 200);
    view2.draw(canvas);
    canvas.save();

    /*for(int i = 0; i < 10; i++) {
        TextView view1 = new TextView(this);//getContentView();
        view1.layout(0, 0, 200, 200);
        view1.setText("Hello"+Integer.toString(i));
        Toast.makeText(this,"Hello"+Integer.toString(i), Toast.LENGTH_SHORT).show();
        view1.draw(canvas);
        // Move the canvas for the next view.
        canvas.save();
        canvas.translate(0, 50);
    }*/
    document.finishPage(page);

    // 输出到文件
    try {
        String filePath = "/sdcard/";
        //String filePath = Environment.getExternalStoragePublicDirectory("").getAbsolutePath();
        //String filePath = Environment.getExternalStorageDirectory().getAbsolutePath();
        String fileName = "easy.pdf";
        File file = new File(filePath, fileName);
        FileOutputStream outputStream = new FileOutputStream(file);
        document.writeTo(outputStream);
        PubUtils.notifySystemToScan(this, filePath + fileName);
        Toast.makeText(this, "导出完成", Toast.LENGTH_SHORT).show();
        SoundUtils.getInstance().playSuccess();
    } catch (IOException e) {
        e.printStackTrace();
        Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();
    }

}