Android应用中怎么对本地pdf文件进行加载

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical">

 <include layout="@layout/common_title" />

 <com.github.barteksc.pdfviewer.PDFView
  android:id="@+id/pdf_view"
  android:layout_width="match_parent"
  android:layout_height="match_parent" />
</LinearLayout>

if (CheckFileExist(title)){
   builderShow = new CustomDialog(ShowPDFActivity.this);
   LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
   View view = inflater.inflate(R.layout.dialog_pdf_progress_new, null);
   builderShow.setContentView(view);
   builderShow.show();
   isDownload=false;
   refushUI();
  }else {
   isDownload=true;
   DownLoadPDF.getInstance().downLoadPDF(ShowPDFActivity.this, //下载路径);

  }

public void refushUI(){
  try {
   pdfView.fromFile(new File(//pdf文件的绝对路径,//标题))
     .defaultPage(1)
     .enableAnnotationRendering(false)
     .onLoad(new OnLoadCompleteListener() {
      @Override
      public void loadComplete(int nbPages) {
       if (isDownload){
        DownLoadPDF.getInstance().closeDilaoig();
       }
       if (builderShow != null&&builderShow.isShowing()) {
        builderShow.dismiss();
       }
      }
     })
     .scrollHandle(null)
     .load();
  }catch (Exception e){
   e.printStackTrace();
  }
 }

private void displayFromAssets(String assetFileName ) {
  pdfView.fromAsset(assetFileName) //设置pdf文件地址
    .defaultPage(6)   //设置默认显示第1页
    .onPageChange(this)  //设置翻页监听
    .onLoad(this)   //设置加载监听
    .onDraw(this)   //绘图监听
    .showMinimap(false)  //pdf放大的时候，是否在屏幕的右上角生成小地图
    .swipeVertical( false ) //pdf文档翻页是否是垂直翻页，默认是左右滑动翻页
    .enableSwipe(true) //是否允许翻页，默认是允许翻页
    // .pages( 2 , 3 , 4 , 5 ) //把2 , 3 , 4 , 5 过滤掉
    .load();
 }

 private void displayFromFile( File file ) {
  pdfView.fromFile(file) //设置pdf文件地址
    .defaultPage(6)   //设置默认显示第1页
    .onPageChange(this)  //设置翻页监听
    .onLoad(this)   //设置加载监听
    .onDraw(this)   //绘图监听
    .showMinimap(false)  //pdf放大的时候，是否在屏幕的右上角生成小地图
    .swipeVertical( false ) //pdf文档翻页是否是垂直翻页，默认是左右滑动翻页
    .enableSwipe(true) //是否允许翻页，默认是允许翻
    // .pages( 2 , 3 , 4 , 5 ) //把2 , 3 , 4 , 5 过滤掉
    .load();
 }

public class DownLoadPDF {
 private static Context context;
 private static File file ;
 private static CustomDialog builder = null ;
 private static Handler ddhandle;
 private static DownLoadPDF instance = null;
 public static DownLoadPDF getInstance(){
  if(instance==null){
   synchronized (DownLoadPDF.class){
    if(instance==null){
     instance = new DownLoadPDF();
    }
   }
  }
  return instance;
 }
 public void downLoadPDF(final Context con, final String url, final String title, final Handler ddhandler) {
  ddhandle = ddhandler;
  context = con;
  builder = new CustomDialog(con);
  LayoutInflater inflater = (LayoutInflater) con.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
  View view = inflater.inflate(R.layout.dialog_pdf_progress_new, null);
  builder.setContentView(view);
  builder.show();

  new Thread() {
   @Override
   public void run() {
    try {
     file = getFileFromServer(url,title);
     sleep(200);
     if (file != null) {
      handler.sendEmptyMessage(2);
     }
    } catch (Exception e) {
     e.printStackTrace();
     builder.dismiss();
     handler.sendEmptyMessage(-1);
    }
   }
  }.start();
 }
 public void closeDilaoig(){
  if (builder != null&&builder.isShowing()) {
   builder.dismiss();
  }
 }public static int length ;
 public static File getFileFromServer(String path,String title)
   throws Exception {
  // 如果相等的话表示当前的sdcard挂载在手机上并且是可用的
  if (Environment.getExternalStorageState().equals(
    Environment.MEDIA_MOUNTED)) {
   URL url = new URL(path);
   HttpURLConnection conn = (HttpURLConnection) url.openConnection();
   conn.setConnectTimeout(5000);
   conn.setDoInput(true);
   conn.connect();
   length = conn.getContentLength();
   InputStream is = conn.getInputStream();
   //将pdf文件存储在指定文件夹下
   File filePath = new File(//指定文件夹路径);
   if (!filePath.exists()){
    filePath.mkdir();
   }
   File file = new File(filePath , title+".pdf");
   FileOutputStream fos = new FileOutputStream(file);
   BufferedInputStream bis = new BufferedInputStream(is);
   byte[] buffer = new byte[1024];
   int len;
   while ((len = bis.read(buffer)) != -1) {
    fos.write(buffer, 0, len);
    handler.sendEmptyMessage(0);
   }
   fos.close();
   bis.close();
   is.close();
   return file;
  } else {
   handler.sendEmptyMessage(-1);
   return null;
  }
 }
 private static Handler handler = new Handler(){
  @Override
  public void handleMessage(Message msg) {
   super.handleMessage(msg);
   switch (msg.what) {
   case 0:
    break;
   case -1:
    //下载失败
    Toast.makeText(context, "下载失败，请稍后再试！", Toast.LENGTH_SHORT).show();
    break;
   case 2:
    ddhandle.sendEmptyMessage(100);
    break;
   default:
    break;
   }
  }

 };
}