我想要下载一张图片并显示在我的imageView组件中。为了下载,我必须使用Asyntask,并显示进度条以通知用户。问题是,在通过循环获取计算出的进度值后,我从inputStream得到了0。
有没有办法获取进度条的计算值,而不是在输入流结束时得到0值?
我在这里使用Asyntask。
澄清:
当我执行以下操作时,bmp将具有一个值:
然而,如果我在执行此操作之前放置循环,则:
Log.d("is", "" + inputStream.available()); // ---> will have a value
byte[] buffer = new byte[contentLenght];
while ((read = inputStream.read(buffer)) != -1) {
counter += read;
publishProgress(counter);
outputStream.write(buffer,0,read);
}
Log.d("is", "" + inputStream.available()); // -----> will return 0
bmp = BitmapFactory.decodeStream(inputStream); // bmp will be empty
有没有办法获取进度条的计算值,而不是在输入流结束时得到0值?
我在这里使用Asyntask。
澄清:
当我执行以下操作时,bmp将具有一个值:
imageView.setImageBitmap(bmp);
仅当我删除循环并只调用bmp = BitmapFactory.decodeStream(inputStream);
时,它才会起作用。然而,如果我在执行此操作之前放置循环,则:
bmp = BitmapFactory.decodeStream(inputStream);
图片视图将不会显示任何内容
以下是包含网络连接的完整异步任务代码
int progressCounter;
int contentLenght;
int counter;
@Override
protected void onPreExecute() {
super.onPreExecute();
progressBar.setVisibility(View.VISIBLE);
}
@Override
protected Boolean doInBackground(String... params) {
return ConnectToInternet(params[0]);
}
@Override
protected void onPostExecute(Boolean aVoid) {
//Log.d("buff",bmp.toString());
progressBar.setVisibility(View.GONE);
imageView.setImageBitmap(bmp);
}
@Override
protected void onProgressUpdate(Integer... values) {
progressCounter =(int) (((double) values[0] / contentLenght) * 100);
progressBar.setProgress(progressCounter);
}
boolean ConnectToInternet(String url){
boolean sucessfull = false;
URL downloadURL = null;
HttpURLConnection connection = null;
InputStream inputStream = null;
try {
downloadURL = new URL(url);
connection = (HttpURLConnection) downloadURL.openConnection();
inputStream = connection.getInputStream();
contentLenght = connection.getContentLength();
Log.d("is", "" + inputStream.available());
int read = -1;
byte[] buffer = new byte[contentLenght];
while ((read = inputStream.read(buffer)) != -1) {
counter += read;
publishProgress(counter);
}
Log.d("is", "" + inputStream.available());
bmp = BitmapFactory.decodeStream(inputStream);
sucessfull = true;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
connection.disconnect();
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sucessfull;
}
谢谢