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