HttpURLConnectionパッケージ非同期ネットワークリクエスト
7022 ワード
/**
* Implementation of AsyncTask, to fetch the data in the background away from
* the UI thread.
*/
private class DownloadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
try {
return loadFromNetwork(urls[0]);
} catch (IOException e) {
return getString(R.string.connection_error);
}
}
/**
* Uses the logging framework to display the output of the fetch
* operation in the log fragment.
*/
@Override
protected void onPostExecute(String result) {
Log.i(TAG, result);
}
}
/** Initiates the fetch operation. */
private String loadFromNetwork(String urlString) throws IOException {
InputStream stream = null;
String str ="";
try {
stream = downloadUrl(urlString);
str = readIt(stream, 500);
} finally {
if (stream != null) {
stream.close();
}
}
return str;
}
/**
* Given a string representation of a URL, sets up a connection and gets
* an input stream.
* @param urlString A string representation of a URL.
* @return An InputStream retrieved from a successful HttpURLConnection.
* @throws java.io.IOException
*/
private InputStream downloadUrl(String urlString) throws IOException {
// BEGIN_INCLUDE(get_inputstream)
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Start the query
conn.connect();
InputStream stream = conn.getInputStream();
return stream;
// END_INCLUDE(get_inputstream)
}
/** Reads an InputStream and converts it to a String.
* @param stream InputStream containing HTML from targeted site.
* @param len Length of string that this method returns.
* @return String concatenated according to len parameter.
* @throws java.io.IOException
* @throws java.io.UnsupportedEncodingException
*/
private String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
Reader reader = null;
reader = new InputStreamReader(stream, "UTF-8");
char[] buffer = new char[len];
reader.read(buffer);
return new String(buffer);
}コールモード
new DownloadTask().execute("http://www.google.com");