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/*
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* Copyright 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.android.networkconnect;
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import android.os.AsyncTask;
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import android.os.Bundle;
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import android.support.v4.app.FragmentActivity;
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import android.util.TypedValue;
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import android.view.Menu;
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import android.view.MenuItem;
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import com.example.android.common.logger.Log;
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import com.example.android.common.logger.LogFragment;
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import com.example.android.common.logger.LogWrapper;
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import com.example.android.common.logger.MessageOnlyLogFilter;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.Reader;
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import java.io.UnsupportedEncodingException;
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import java.net.HttpURLConnection;
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import java.net.URL;
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/**
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* Sample application demonstrating how to connect to the network and fetch raw
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* HTML. It uses AsyncTask to do the fetch on a background thread. To establish
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* the network connection, it uses HttpURLConnection.
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*
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* This sample uses the logging framework to display log output in the log
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* fragment (LogFragment).
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*/
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public class MainActivity extends FragmentActivity {
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public static final String TAG = "Network Connect";
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// Reference to the fragment showing events, so we can clear it with a button
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// as necessary.
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private LogFragment mLogFragment;
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@Override
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protected void onCreate(Bundle savedInstanceState) {
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super.onCreate(savedInstanceState);
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setContentView(R.layout.sample_main);
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// Initialize text fragment that displays intro text.
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SimpleTextFragment introFragment = (SimpleTextFragment)
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getSupportFragmentManager().findFragmentById(R.id.intro_fragment);
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introFragment.setText(R.string.welcome_message);
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introFragment.getTextView().setTextSize(TypedValue.COMPLEX_UNIT_DIP, 16.0f);
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// Initialize the logging framework.
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initializeLogging();
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}
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@Override
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public boolean onCreateOptionsMenu(Menu menu) {
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getMenuInflater().inflate(R.menu.main, menu);
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return true;
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}
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@Override
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public boolean onOptionsItemSelected(MenuItem item) {
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switch (item.getItemId()) {
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// When the user clicks FETCH, fetch the first 500 characters of
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// raw HTML from www.google.com.
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case R.id.fetch_action:
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new DownloadTask().execute("http://www.google.com");
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return true;
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// Clear the log view fragment.
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case R.id.clear_action:
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mLogFragment.getLogView().setText("");
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return true;
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}
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return false;
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}
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/**
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* Implementation of AsyncTask, to fetch the data in the background away from
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* the UI thread.
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*/
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private class DownloadTask extends AsyncTask<String, Void, String> {
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@Override
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protected String doInBackground(String... urls) {
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try {
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return loadFromNetwork(urls[0]);
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} catch (IOException e) {
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return getString(R.string.connection_error);
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}
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}
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/**
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* Uses the logging framework to display the output of the fetch
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* operation in the log fragment.
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*/
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@Override
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protected void onPostExecute(String result) {
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Log.i(TAG, result);
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}
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}
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/** Initiates the fetch operation. */
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private String loadFromNetwork(String urlString) throws IOException {
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InputStream stream = null;
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String str ="";
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try {
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stream = downloadUrl(urlString);
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str = readIt(stream, 500);
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} finally {
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if (stream != null) {
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stream.close();
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}
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}
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return str;
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}
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/**
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* Given a string representation of a URL, sets up a connection and gets
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* an input stream.
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* @param urlString A string representation of a URL.
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* @return An InputStream retrieved from a successful HttpURLConnection.
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* @throws java.io.IOException
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*/
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private InputStream downloadUrl(String urlString) throws IOException {
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URL url = new URL(urlString);
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HttpURLConnection conn = (HttpURLConnection) url.openConnection();
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conn.setReadTimeout(10000 /* milliseconds */);
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conn.setConnectTimeout(15000 /* milliseconds */);
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conn.setRequestMethod("GET");
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conn.setDoInput(true);
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// Start the query
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conn.connect();
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InputStream stream = conn.getInputStream();
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return stream;
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}
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/** Reads an InputStream and converts it to a String.
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* @param stream InputStream containing HTML from targeted site.
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* @param len Length of string that this method returns.
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* @return String concatenated according to len parameter.
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* @throws java.io.IOException
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* @throws java.io.UnsupportedEncodingException
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*/
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private String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
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Reader reader = null;
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reader = new InputStreamReader(stream, "UTF-8");
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char[] buffer = new char[len];
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reader.read(buffer);
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return new String(buffer);
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}
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/** Create a chain of targets that will receive log data */
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public void initializeLogging() {
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// Using Log, front-end to the logging chain, emulates
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// android.util.log method signatures.
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// Wraps Android's native log framework
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LogWrapper logWrapper = new LogWrapper();
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Log.setLogNode(logWrapper);
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// A filter that strips out everything except the message text.
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MessageOnlyLogFilter msgFilter = new MessageOnlyLogFilter();
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logWrapper.setNext(msgFilter);
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// On screen logging via a fragment with a TextView.
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mLogFragment =
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(LogFragment) getSupportFragmentManager().findFragmentById(R.id.log_fragment);
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msgFilter.setNext(mLogFragment.getLogView());
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}
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}