samples/Wiktionary/src/com/example/android/wiktionary/SimpleWikiHelper.java - platform/development - Git at Google

 /*
  * 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);
         }
     }

 }
	/*
	* 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);
	}
	}

	}