1 /* 2 * Copyright 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.networkconnect; 18 19 import android.os.AsyncTask; 20 import android.os.Bundle; 21 import android.support.v4.app.FragmentActivity; 22 import android.util.TypedValue; 23 import android.view.Menu; 24 import android.view.MenuItem; 25 26 import com.example.android.common.logger.Log; 27 import com.example.android.common.logger.LogFragment; 28 import com.example.android.common.logger.LogWrapper; 29 import com.example.android.common.logger.MessageOnlyLogFilter; 30 31 import java.io.IOException; 32 import java.io.InputStream; 33 import java.io.InputStreamReader; 34 import java.io.Reader; 35 import java.io.UnsupportedEncodingException; 36 import java.net.HttpURLConnection; 37 import java.net.URL; 38 39 /** 40 * Sample application demonstrating how to connect to the network and fetch raw 41 * HTML. It uses AsyncTask to do the fetch on a background thread. To establish 42 * the network connection, it uses HttpURLConnection. 43 * 44 * This sample uses the logging framework to display log output in the log 45 * fragment (LogFragment). 46 */ 47 public class MainActivity extends FragmentActivity { 48 49 public static final String TAG = "Network Connect"; 50 51 // Reference to the fragment showing events, so we can clear it with a button 52 // as necessary. 53 private LogFragment mLogFragment; 54 55 @Override 56 protected void onCreate(Bundle savedInstanceState) { 57 super.onCreate(savedInstanceState); 58 setContentView(R.layout.sample_main); 59 60 // Initialize text fragment that displays intro text. 61 SimpleTextFragment introFragment = (SimpleTextFragment) 62 getSupportFragmentManager().findFragmentById(R.id.intro_fragment); 63 introFragment.setText(R.string.welcome_message); 64 introFragment.getTextView().setTextSize(TypedValue.COMPLEX_UNIT_DIP, 16.0f); 65 66 // Initialize the logging framework. 67 initializeLogging(); 68 } 69 70 @Override 71 public boolean onCreateOptionsMenu(Menu menu) { 72 getMenuInflater().inflate(R.menu.main, menu); 73 return true; 74 } 75 76 @Override 77 public boolean onOptionsItemSelected(MenuItem item) { 78 switch (item.getItemId()) { 79 // When the user clicks FETCH, fetch the first 500 characters of 80 // raw HTML from www.google.com. 81 case R.id.fetch_action: 82 new DownloadTask().execute("http://www.google.com"); 83 return true; 84 // Clear the log view fragment. 85 case R.id.clear_action: 86 mLogFragment.getLogView().setText(""); 87 return true; 88 } 89 return false; 90 } 91 92 /** 93 * Implementation of AsyncTask, to fetch the data in the background away from 94 * the UI thread. 95 */ 96 private class DownloadTask extends AsyncTask<String, Void, String> { 97 98 @Override 99 protected String doInBackground(String... urls) { 100 try { 101 return loadFromNetwork(urls[0]); 102 } catch (IOException e) { 103 return getString(R.string.connection_error); 104 } 105 } 106 107 /** 108 * Uses the logging framework to display the output of the fetch 109 * operation in the log fragment. 110 */ 111 @Override 112 protected void onPostExecute(String result) { 113 Log.i(TAG, result); 114 } 115 } 116 117 /** Initiates the fetch operation. */ 118 private String loadFromNetwork(String urlString) throws IOException { 119 InputStream stream = null; 120 String str =""; 121 122 try { 123 stream = downloadUrl(urlString); 124 str = readIt(stream, 500); 125 } finally { 126 if (stream != null) { 127 stream.close(); 128 } 129 } 130 return str; 131 } 132 133 /** 134 * Given a string representation of a URL, sets up a connection and gets 135 * an input stream. 136 * @param urlString A string representation of a URL. 137 * @return An InputStream retrieved from a successful HttpURLConnection. 138 * @throws java.io.IOException 139 */ 140 private InputStream downloadUrl(String urlString) throws IOException { 142 URL url = new URL(urlString); 143 HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 144 conn.setReadTimeout(10000 /* milliseconds */); 145 conn.setConnectTimeout(15000 /* milliseconds */); 146 conn.setRequestMethod("GET"); 147 conn.setDoInput(true); 148 // Start the query 149 conn.connect(); 150 InputStream stream = conn.getInputStream(); 151 return stream; 153 } 154 155 /** Reads an InputStream and converts it to a String. 156 * @param stream InputStream containing HTML from targeted site. 157 * @param len Length of string that this method returns. 158 * @return String concatenated according to len parameter. 159 * @throws java.io.IOException 160 * @throws java.io.UnsupportedEncodingException 161 */ 162 private String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException { 163 Reader reader = null; 164 reader = new InputStreamReader(stream, "UTF-8"); 165 char[] buffer = new char[len]; 166 reader.read(buffer); 167 return new String(buffer); 168 } 169 170 /** Create a chain of targets that will receive log data */ 171 public void initializeLogging() { 172 173 // Using Log, front-end to the logging chain, emulates 174 // android.util.log method signatures. 175 176 // Wraps Android's native log framework 177 LogWrapper logWrapper = new LogWrapper(); 178 Log.setLogNode(logWrapper); 179 180 // A filter that strips out everything except the message text. 181 MessageOnlyLogFilter msgFilter = new MessageOnlyLogFilter(); 182 logWrapper.setNext(msgFilter); 183 184 // On screen logging via a fragment with a TextView. 185 mLogFragment = 186 (LogFragment) getSupportFragmentManager().findFragmentById(R.id.log_fragment); 187 msgFilter.setNext(mLogFragment.getLogView()); 188 } 189 }