Question

我对Android开发相当新，所以我想做的是可以从url显示pdf的应用程序，

我希望在从web加载pdf文件时显示进度条（某些pdf文件大于15mb）我该怎么做？

iam使用com.github.barteksc.pdfviewer.PDFView来显示来自网络的pdf

这是我的pdf节目活动

private PDFView mPDFview;

private String mStoreId;

private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference mReference;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_flyer);


    mFirebaseDatabase = FirebaseDatabase.getInstance();
    mReference = mFirebaseDatabase.getReference("Store");

    if (getIntent()!=null)
    {
        mStoreId = getIntent().getStringExtra("StoreId");
    }

    if (!mStoreId.isEmpty())
    {
        getUrlStoreFlyer(mStoreId);
    }

}

private void getUrlStoreFlyer(String storeId) {
    mReference.child(storeId).addValueEventListener(new ValueEventListener() 
{
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Store storeChain = dataSnapshot.getValue(Store.class);
            String pdfUrl = storeChain.getFlyerPDF().toString();
            mPDFview = findViewById(R.id.flyer_pdfView);
            new RetrievePDFStream().execute(pdfUrl);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });
}

class RetrievePDFStream extends AsyncTask<String, Void, InputStream>
{
    @Override
    protected InputStream doInBackground(String... strings)
    {
        InputStream inputStream = null;
        try{
            URL url = new URL(strings[0]);
            HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();

            if (urlConnection.getResponseCode()==200)
            {
                inputStream = new BufferedInputStream(urlConnection.getInputStream());
            }
        }
        catch (IOException e)
        {
            return null;
        }

        return inputStream;
    }

    @Override
    protected void onPostExecute(InputStream inputStream) {
        mPDFview.fromStream(inputStream).load();
    }
}

@Override
public void onBackPressed() {
    finish();
    overridePendingTransition(0, 0);
}
}

这是我的xml

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.test.FlyerActivity">


    <ProgressBar

        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="150dp"
        android:id="@+id/progressBar2" />



    <com.github.barteksc.pdfviewer.PDFView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/flyer_pdfView"/>
    enter code here

</RelativeLayout>

Answer 1

这是我使用和完美的工作：

   @Override
    protected void onPostExecute(InputStream inputStream) {

        mPDFview.fromStream(inputStream).onLoad(new OnLoadCompleteListener() {
            @Override
            public void loadComplete(int nbPages) {
                ProgressBar progressBar = (ProgressBar) findViewById(R.id.progressBar2);
                progressBar.setVisibility(View.GONE);
            }
        }).load();

    }

Answer 2

  private PDFView mPDFview;

  private String mStoreId;
  //add progressbar
  private ProgressBar progressBar;

  private FirebaseDatabase mFirebaseDatabase;
  private DatabaseReference mReference;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_flyer);
//initialize
progressBar = (ProgressBar) findViewById(R.id.progressBar);

mFirebaseDatabase = FirebaseDatabase.getInstance();
mReference = mFirebaseDatabase.getReference("Store");

if (getIntent()!=null)
{
    mStoreId = getIntent().getStringExtra("StoreId");
}

if (!mStoreId.isEmpty())
{
    getUrlStoreFlyer(mStoreId);
}

}

private void getUrlStoreFlyer(String storeId) {
    mReference.child(storeId).addValueEventListener(new ValueEventListener() 
{
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Store storeChain = dataSnapshot.getValue(Store.class);
            String pdfUrl = storeChain.getFlyerPDF().toString();
            mPDFview = findViewById(R.id.flyer_pdfView);
            new RetrievePDFStream().execute(pdfUrl);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });
}

class RetrievePDFStream extends AsyncTask<String, Void, InputStream>
{

   @Override
    protected void onPExecute(InputStream inputStream) {
        progressBar.setVisibility(View.VISIBLE);
    }

    @Override
    protected InputStream doInBackground(String... strings)
    {
        InputStream inputStream = null;
        try{
            URL url = new URL(strings[0]);
            HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();

            if (urlConnection.getResponseCode()==200)
            {
                inputStream = new BufferedInputStream(urlConnection.getInputStream());
            }
        }
        catch (IOException e)
        {
            return null;
        }

        return inputStream;
    }

    @Override
    protected void onPostExecute(InputStream inputStream) {
        mPDFview.fromStream(inputStream).load();
        progressBar.setVisibility(View.GONE);

    }
}

@Override
public void onBackPressed() {
    finish();
    overridePendingTransition(0, 0);
    progressBar.setVisibility(View.GONE);

}
}

Answer 3

由于您正在使用库从输入流加载PDF，因此可以采用以下方式。

在执行异步任务之前，使进度条可见，PDFView不可见。

progressBar = findViewById(R.id.progressBar2); mPDFview = findViewById(R.id.flyer_pdfView); progressBar.setVisibility(View.VISIBLE); mPDFview.setVisibility(View.INVISIBLE); new RetrievePDFStream().execute(pdfUrl);
在AsyncTask的onPostExecute()中，您可以在网络调用完成后执行UI操作。所以在这里，您必须使PDFView可见并且progressBar不可见，但是由于您正在进行网络操作然后将其传输到PDFView，因此PDFView也需要时间来流式传输内容。我查找了你正在使用的库，我相信它有一个名为onLoad(onLoadCompleteListener)的函数，你可以使用这个函数和fromStream()来使进度条不可见，pdfView可见。

@Override protected void onPostExecute(InputStream inputStream) { mPDFview.fromStream(inputStream).onLoad(this).load(); }

@Override public void loadComplete(int nbPages) { progressBar.setVisibilitiy(INVISIBLE); mPDFView.setVisibility(VISIBLE); }

或者，由于您使用的库实际上可以从URI加载PDF，因此您根本不需要使用Async Task。只需致电PDFView.fromUri(uri).onLoad(this).load();

加载pdf文件时显示进度条

3 个答案: