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[英]How to Show the progress bar while the url is loading in WebView Android
[英]Show progress bar while loading pdf file
iam对于android开发来说还是相当新的东西,所以iam试图制作的应用程序可以显示url中的pdf,
我要在从Web加载pdf文件时显示进度栏(某些pdf文件超过15mb大)我该怎么做?
iam使用com.github.barteksc.pdfviewer.PDFView
来显示来自Web的pdf
这是我的pdf表演活动
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>
这是我使用并完美工作的内容:
@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();
}
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);
}
}
由于您正在使用库从输入流中加载PDF,因此可以执行以下操作。
在执行异步任务之前,使进度条可见,而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);
在网络调用完成之后,您可以在AsyncTask的onPostExecute()
中执行UI操作。 因此,在这里,您将必须使PDFView可见,而progressBar不可见,而且由于要进行网络操作,然后将其流式传输到PDFView,PDFView也将花费时间来流式传输内容。 我查看了正在使用的库,并相信它具有一个名为onLoad(onLoadCompleteListener)
的函数,您可以将该函数与fromStream()
一起使用,以使进度条不可见,而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); }
另外,由于使用的库实际上可以从URI加载PDF,因此根本不需要使用“异步任务”。 只需调用PDFView.fromUri(uri).onLoad(this).load();
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