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/*
* 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 com.example.android.wiktionary;
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 java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* 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 SimpleWikiHelper {
private static final String TAG = "SimpleWikiHelper";
/**
* 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";
/**
* 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 WIKTIONARY_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 encodedTitle = Uri.encode(title);
String expandClause = expandTemplates ? WIKTIONARY_EXPAND_TEMPLATES : "";
// Query the API for content
String content = getUrlContent(String.format(WIKTIONARY_PAGE,
encodedTitle, expandClause));
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);
}
}
/**
* 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);
}
}
}
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