1 /* 2 * Copyright (C) 2009 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.simplewiktionary; 18 19 import org.apache.http.HttpEntity; 20 import org.apache.http.HttpResponse; 21 import org.apache.http.StatusLine; 22 import org.apache.http.client.HttpClient; 23 import org.apache.http.client.methods.HttpGet; 24 import org.apache.http.impl.client.DefaultHttpClient; 25 import org.json.JSONArray; 26 import org.json.JSONException; 27 import org.json.JSONObject; 28 29 import android.content.Context; 30 import android.content.pm.PackageInfo; 31 import android.content.pm.PackageManager; 32 import android.content.pm.PackageManager.NameNotFoundException; 33 import android.net.Uri; 34 import android.util.Log; 35 36 import java.io.ByteArrayOutputStream; 37 import java.io.IOException; 38 import java.io.InputStream; 39 40 /** 41 * Helper methods to simplify talking with and parsing responses from a 42 * lightweight Wiktionary API. Before making any requests, you should call 43 * {@link #prepareUserAgent(Context)} to generate a User-Agent string based on 44 * your application package name and version. 45 */ 46 public class SimpleWikiHelper { 47 private static final String TAG = "SimpleWikiHelper"; 48 49 /** 50 * Regular expression that splits "Word of the day" entry into word 51 * name, word type, and the first description bullet point. 52 */ 53 public static final String WORD_OF_DAY_REGEX = 54 "(?s)\\{\\{wotd\\|(.+?)\\|(.+?)\\|([^#\\|]+).*?\\}\\}"; 55 56 /** 57 * Partial URL to use when requesting the detailed entry for a specific 58 * Wiktionary page. Use {@link String#format(String, Object...)} to insert 59 * the desired page title after escaping it as needed. 60 */ 61 private static final String WIKTIONARY_PAGE = 62 "http://en.wiktionary.org/w/api.php?action=query&prop=revisions&titles=%s&" + 63 "rvprop=content&format=json%s"; 64 65 /** 66 * Partial URL to append to {@link #WIKTIONARY_PAGE} when you want to expand 67 * any templates found on the requested page. This is useful when browsing 68 * full entries, but may use more network bandwidth. 69 */ 70 private static final String WIKTIONARY_EXPAND_TEMPLATES = 71 "&rvexpandtemplates=true"; 72 73 /** 74 * {@link StatusLine} HTTP status code when no server error has occurred. 75 */ 76 private static final int HTTP_STATUS_OK = 200; 77 78 /** 79 * Shared buffer used by {@link #getUrlContent(String)} when reading results 80 * from an API request. 81 */ 82 private static byte[] sBuffer = new byte[512]; 83 84 /** 85 * User-agent string to use when making requests. Should be filled using 86 * {@link #prepareUserAgent(Context)} before making any other calls. 87 */ 88 private static String sUserAgent = null; 89 90 /** 91 * Thrown when there were problems contacting the remote API server, either 92 * because of a network error, or the server returned a bad status code. 93 */ 94 public static class ApiException extends Exception { 95 public ApiException(String detailMessage, Throwable throwable) { 96 super(detailMessage, throwable); 97 } 98 99 public ApiException(String detailMessage) { 100 super(detailMessage); 101 } 102 } 103 104 /** 105 * Thrown when there were problems parsing the response to an API call, 106 * either because the response was empty, or it was malformed. 107 */ 108 public static class ParseException extends Exception { 109 public ParseException(String detailMessage, Throwable throwable) { 110 super(detailMessage, throwable); 111 } 112 } 113 114 /** 115 * Prepare the internal User-Agent string for use. This requires a 116 * {@link Context} to pull the package name and version number for this 117 * application. 118 */ 119 public static void prepareUserAgent(Context context) { 120 try { 121 // Read package name and version number from manifest 122 PackageManager manager = context.getPackageManager(); 123 PackageInfo info = manager.getPackageInfo(context.getPackageName(), 0); 124 sUserAgent = String.format(context.getString(R.string.template_user_agent), 125 info.packageName, info.versionName); 126 127 } catch(NameNotFoundException e) { 128 Log.e(TAG, "Couldn't find package information in PackageManager", e); 129 } 130 } 131 132 /** 133 * Read and return the content for a specific Wiktionary page. This makes a 134 * lightweight API call, and trims out just the page content returned. 135 * Because this call blocks until results are available, it should not be 136 * run from a UI thread. 137 * 138 * @param title The exact title of the Wiktionary page requested. 139 * @param expandTemplates If true, expand any wiki templates found. 140 * @return Exact content of page. 141 * @throws ApiException If any connection or server error occurs. 142 * @throws ParseException If there are problems parsing the response. 143 */ 144 public static String getPageContent(String title, boolean expandTemplates) 145 throws ApiException, ParseException { 146 // Encode page title and expand templates if requested 147 String encodedTitle = Uri.encode(title); 148 String expandClause = expandTemplates ? WIKTIONARY_EXPAND_TEMPLATES : ""; 149 150 // Query the API for content 151 String content = getUrlContent(String.format(WIKTIONARY_PAGE, 152 encodedTitle, expandClause)); 153 try { 154 // Drill into the JSON response to find the content body 155 JSONObject response = new JSONObject(content); 156 JSONObject query = response.getJSONObject("query"); 157 JSONObject pages = query.getJSONObject("pages"); 158 JSONObject page = pages.getJSONObject((String) pages.keys().next()); 159 JSONArray revisions = page.getJSONArray("revisions"); 160 JSONObject revision = revisions.getJSONObject(0); 161 return revision.getString("*"); 162 } catch (JSONException e) { 163 throw new ParseException("Problem parsing API response", e); 164 } 165 } 166 167 /** 168 * Pull the raw text content of the given URL. This call blocks until the 169 * operation has completed, and is synchronized because it uses a shared 170 * buffer {@link #sBuffer}. 171 * 172 * @param url The exact URL to request. 173 * @return The raw content returned by the server. 174 * @throws ApiException If any connection or server error occurs. 175 */ 176 protected static synchronized String getUrlContent(String url) throws ApiException { 177 if (sUserAgent == null) { 178 throw new ApiException("User-Agent string must be prepared"); 179 } 180 181 // Create client and set our specific user-agent string 182 HttpClient client = new DefaultHttpClient(); 183 HttpGet request = new HttpGet(url); 184 request.setHeader("User-Agent", sUserAgent); 185 186 try { 187 HttpResponse response = client.execute(request); 188 189 // Check if server response is valid 190 StatusLine status = response.getStatusLine(); 191 if (status.getStatusCode() != HTTP_STATUS_OK) { 192 throw new ApiException("Invalid response from server: " + 193 status.toString()); 194 } 195 196 // Pull content stream from response 197 HttpEntity entity = response.getEntity(); 198 InputStream inputStream = entity.getContent(); 199 200 ByteArrayOutputStream content = new ByteArrayOutputStream(); 201 202 // Read response into a buffered stream 203 int readBytes = 0; 204 while ((readBytes = inputStream.read(sBuffer)) != -1) { 205 content.write(sBuffer, 0, readBytes); 206 } 207 208 // Return result from buffered stream 209 return new String(content.toByteArray()); 210 } catch (IOException e) { 211 throw new ApiException("Problem communicating with API", e); 212 } 213 } 214 } 215
