由于没有在运行时请求写入权限，我最初遇到了一些问题，但我似乎已经解决了这个问题。代码从网站上抓取了一个pdf文件，并且应该将它存储在app目录中，我已经设置了post执行文件，将textView设置为创建文件的目标目录。没有创建文件，也没有异常，所以我在这里很难过
public class MainActivity extends AppCompatActivity implements ActivityCompat.OnRequestPermissionsResultCallback {
private static final int REQUEST_WRITE_PERMISSION = 786;
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
if (requestCode == REQUEST_WRITE_PERMISSION && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
new FetchWebsiteData(this).execute();
}
}
private void requestPermission() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_WRITE_PERMISSION);
} else {
//do something
//new FetchWebsiteData().execute();
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnFetchData = (Button) findViewById(R.id.buttonTest);
btnFetchData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
requestPermission();
}
});
}
private class FetchWebsiteData extends AsyncTask<Void, Void, Void> {
private String pdfLink = "didnt work";
private Link foundLink = new Link("");
String fileLocation= "";
Context context;
public FetchWebsiteData(Context context1){
context = context1;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params) {
int count;
try {
Document doc = Jsoup.connect("http://www.dunnesstores.com/offer20/food-wine/fcp-category/home").userAgent("Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0) Gecko/20100101 Firefox/5.0").get();
//Elements links = doc.select("a[title=\"Download offers in store\"]");
Element links = doc.select("a[title=\"Download offers in store\"]").first();
foundLink = new Link(links.attr("href"));
URL url = new URL(foundLink.getUrlWithDomain());
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//set up some things on the connection
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//and connect!
urlConnection.connect();
File file = new File(context.getFilesDir(),foundLink.getFileNameOnly());
fileLocation = file.toString();
//this will be used to write the downloaded data into the file we created
FileOutputStream fileOutput = new FileOutputStream(file);
//this will be used in reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file
int totalSize = urlConnection.getContentLength();
//variable to store total downloaded bytes
int downloadedSize = 0;
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0; //used to store a temporary size of the buffer
//now, read through the input buffer and write the contents to the file
while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
//add the data in the buffer to the file in the file output stream (the file on the sd card
fileOutput.write(buffer, 0, bufferLength);
//add up the size so we know how much is downloaded
downloadedSize += bufferLength;
//this is where you would do something to report the prgress, like this maybe
}
//close the output stream when done
fileOutput.close();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
TextView txttitle = (TextView) findViewById(R.id.resultTextView);
//testing the file location
txttitle.setText(fileLocation);
}
}