Java tutorial
/* * Copyright (C) 2009 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package fr.spaz.widget.pedia; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.List; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.StatusLine; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import android.content.Context; import android.content.pm.PackageInfo; import android.content.pm.PackageManager; import android.content.pm.PackageManager.NameNotFoundException; import android.net.Uri; import android.util.Log; import fr.spaz.widget.R; /** * Helper methods to simplify talking with and parsing responses from a * lightweight Wiktionary API. Before making any requests, you should call * {@link #prepareUserAgent(Context)} to generate a User-Agent string based on * your application package name and version. */ public class SimpleWikipediaHelper { private static final String TAG = "SimpleWikiHelper"; /** * Regular expression that splits "Word of the day" entry into word name, * word type, and the first description bullet point. */ // public static final String WORD_OF_DAY_REGEX = // "(?s)\\{\\{wotd\\|(.+?)\\|(.+?)\\|([^#\\|]+).*?\\}\\}"; /** * Partial URL to use when requesting the detailed entry for a specific * Wiktionary page. Use {@link String#format(String, Object...)} to insert * the desired page title after escaping it as needed. */ // private static final String WIKTIONARY_PAGE = // "http://en.wiktionary.org/w/api.php?action=query&prop=revisions&titles=%s&rvprop=content&format=json%s"; private static final String WIKIPEDIA_PAGE = "http://%s.wikipedia.org/w/api.php?action=query&prop=revisions&titles=%s&rvprop=content&format=json&rvparse%s"; // private static final String WIKIPEDIA_PAGE_RANDOM = // "fr.wikipedia.org/wiki/Spcial:Page_au_hasard"; private static final String WIKIPEDIA_PAGE_RANDOM = "http://%s.wikipedia.org/w/api.php?action=query&list=random&rvsection=0&format=json&rnnamespace=0&rnlimit=%d"; /** * Partial URL to append to {@link #WIKTIONARY_PAGE} when you want to expand * any templates found on the requested page. This is useful when browsing * full entries, but may use more network bandwidth. */ private static final String WIKIPEDIA_EXPAND_TEMPLATES = "&rvexpandtemplates=true"; /** * {@link StatusLine} HTTP status code when no server error has occurred. */ private static final int HTTP_STATUS_OK = 200; /** * Shared buffer used by {@link #getUrlContent(String)} when reading results * from an API request. */ private static byte[] sBuffer = new byte[512]; /** * User-agent string to use when making requests. Should be filled using * {@link #prepareUserAgent(Context)} before making any other calls. */ private static String sUserAgent = null; /** * Thrown when there were problems contacting the remote API server, either * because of a network error, or the server returned a bad status code. */ public static class ApiException extends Exception { public ApiException(String detailMessage, Throwable throwable) { super(detailMessage, throwable); } public ApiException(String detailMessage) { super(detailMessage); } } /** * Thrown when there were problems parsing the response to an API call, * either because the response was empty, or it was malformed. */ public static class ParseException extends Exception { public ParseException(String detailMessage, Throwable throwable) { super(detailMessage, throwable); } } /** * Prepare the internal User-Agent string for use. This requires a * {@link Context} to pull the package name and version number for this * application. */ public static void prepareUserAgent(Context context) { try { // Read package name and version number from manifest PackageManager manager = context.getPackageManager(); PackageInfo info = manager.getPackageInfo(context.getPackageName(), 0); sUserAgent = String.format(context.getString(R.string.template_user_agent), info.packageName, info.versionName); } catch (NameNotFoundException e) { Log.e(TAG, "Couldn't find package information in PackageManager", e); } } /** * Read and return the content for a specific Wiktionary page. This makes a * lightweight API call, and trims out just the page content returned. * Because this call blocks until results are available, it should not be * run from a UI thread. * * @param title * The exact title of the Wiktionary page requested. * @param expandTemplates * If true, expand any wiki templates found. * @return Exact content of page. * @throws ApiException * If any connection or server error occurs. * @throws ParseException * If there are problems parsing the response. */ public static String getPageContent(String title, boolean expandTemplates) throws ApiException, ParseException { // Encode page title and expand templates if requested String lang = Uri.encode("en"); String encodedTitle = Uri.encode(title); String expandClause = expandTemplates ? WIKIPEDIA_EXPAND_TEMPLATES : ""; // Query the API for content final String s = String.format(WIKIPEDIA_PAGE, lang, encodedTitle, expandClause); Log.d("Spaz", s); String content = getUrlContent(s); try { // Drill into the JSON response to find the content body JSONObject response = new JSONObject(content); JSONObject query = response.getJSONObject("query"); JSONObject pages = query.getJSONObject("pages"); JSONObject page = pages.getJSONObject((String) pages.keys().next()); JSONArray revisions = page.getJSONArray("revisions"); JSONObject revision = revisions.getJSONObject(0); return revision.getString("*"); } catch (JSONException e) { throw new ParseException("Problem parsing API response", e); } } public static List<String> getRandomPages(int nbItem) throws ApiException, ParseException { // Encode page title and expand templates if requested String lang = Uri.encode("en"); // Query the API for content String queryString = String.format(WIKIPEDIA_PAGE_RANDOM, lang, nbItem); String content = getUrlContent(queryString); try { List<String> res = new ArrayList<String>(); // Drill into the JSON response to find the content body JSONObject response = new JSONObject(content); JSONObject query = response.getJSONObject("query"); JSONArray random = query.getJSONArray("random"); for (int i = 0; i < random.length(); i++) { JSONObject page = random.getJSONObject(i); res.add(page.getString("title")); } return res; } catch (JSONException e) { throw new ParseException("Problem parsing API response", e); } } /** * Pull the raw text content of the given URL. This call blocks until the * operation has completed, and is synchronized because it uses a shared * buffer {@link #sBuffer}. * * @param url * The exact URL to request. * @return The raw content returned by the server. * @throws ApiException * If any connection or server error occurs. */ protected static synchronized String getUrlContent(String url) throws ApiException { if (sUserAgent == null) { throw new ApiException("User-Agent string must be prepared"); } // Create client and set our specific user-agent string HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(url); request.setHeader("User-Agent", sUserAgent); try { HttpResponse response = client.execute(request); // Check if server response is valid StatusLine status = response.getStatusLine(); if (status.getStatusCode() != HTTP_STATUS_OK) { throw new ApiException("Invalid response from server: " + status.toString()); } // Pull content stream from response HttpEntity entity = response.getEntity(); InputStream inputStream = entity.getContent(); ByteArrayOutputStream content = new ByteArrayOutputStream(); // Read response into a buffered stream int readBytes = 0; while ((readBytes = inputStream.read(sBuffer)) != -1) { content.write(sBuffer, 0, readBytes); } // Return result from buffered stream return new String(content.toByteArray()); } catch (IOException e) { throw new ApiException("Problem communicating with API", e); } } }