Java tutorial
/* * Copyright (C) 2010 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.android.browser.search; import com.android.browser.R; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import java.nio.charset.Charset; import java.nio.charset.IllegalCharsetNameException; import java.nio.charset.UnsupportedCharsetException; import libcore.io.Streams; import libcore.net.http.ResponseUtils; import org.json.JSONArray; import org.json.JSONException; import android.app.SearchManager; import android.content.Context; import android.content.Intent; import android.database.AbstractCursor; import android.database.Cursor; import android.net.ConnectivityManager; import android.net.NetworkInfo; import android.net.Uri; import android.os.Bundle; import android.provider.Browser; import android.text.TextUtils; import android.util.Log; import java.io.IOException; /** * Provides search suggestions, if any, for a given web search provider. */ public class OpenSearchSearchEngine implements SearchEngine { private static final String TAG = "OpenSearchSearchEngine"; private static final String USER_AGENT = "Android/1.0"; private static final int HTTP_TIMEOUT_MS = 1000; // Indices of the columns in the below arrays. private static final int COLUMN_INDEX_ID = 0; private static final int COLUMN_INDEX_QUERY = 1; private static final int COLUMN_INDEX_ICON = 2; private static final int COLUMN_INDEX_TEXT_1 = 3; private static final int COLUMN_INDEX_TEXT_2 = 4; // The suggestion columns used. If you are adding a new entry to these arrays make sure to // update the list of indices declared above. private static final String[] COLUMNS = new String[] { "_id", SearchManager.SUGGEST_COLUMN_QUERY, SearchManager.SUGGEST_COLUMN_ICON_1, SearchManager.SUGGEST_COLUMN_TEXT_1, SearchManager.SUGGEST_COLUMN_TEXT_2, }; private static final String[] COLUMNS_WITHOUT_DESCRIPTION = new String[] { "_id", SearchManager.SUGGEST_COLUMN_QUERY, SearchManager.SUGGEST_COLUMN_ICON_1, SearchManager.SUGGEST_COLUMN_TEXT_1, }; private final SearchEngineInfo mSearchEngineInfo; public OpenSearchSearchEngine(Context context, SearchEngineInfo searchEngineInfo) { mSearchEngineInfo = searchEngineInfo; } public String getName() { return mSearchEngineInfo.getName(); } public CharSequence getLabel() { return mSearchEngineInfo.getLabel(); } public void startSearch(Context context, String query, Bundle appData, String extraData) { String uri = mSearchEngineInfo.getSearchUriForQuery(query); if (uri == null) { Log.e(TAG, "Unable to get search URI for " + mSearchEngineInfo); } else { Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri)); // Make sure the intent goes to the Browser itself intent.setPackage(context.getPackageName()); intent.addCategory(Intent.CATEGORY_DEFAULT); intent.putExtra(SearchManager.QUERY, query); if (appData != null) { intent.putExtra(SearchManager.APP_DATA, appData); } if (extraData != null) { intent.putExtra(SearchManager.EXTRA_DATA_KEY, extraData); } intent.putExtra(Browser.EXTRA_APPLICATION_ID, context.getPackageName()); context.startActivity(intent); } } /** * Queries for a given search term and returns a cursor containing * suggestions ordered by best match. */ public Cursor getSuggestions(Context context, String query) { if (TextUtils.isEmpty(query)) { return null; } if (!isNetworkConnected(context)) { Log.i(TAG, "Not connected to network."); return null; } String suggestUri = mSearchEngineInfo.getSuggestUriForQuery(query); if (TextUtils.isEmpty(suggestUri)) { // No suggest URI available for this engine return null; } try { String content = readUrl(suggestUri); if (content == null) return null; /* The data format is a JSON array with items being regular strings or JSON arrays * themselves. We are interested in the second and third elements, both of which * should be JSON arrays. The second element/array contains the suggestions and the * third element contains the descriptions. Some search engines don't support * suggestion descriptions so the third element is optional. */ JSONArray results = new JSONArray(content); JSONArray suggestions = results.getJSONArray(1); JSONArray descriptions = null; if (results.length() > 2) { descriptions = results.getJSONArray(2); // Some search engines given an empty array "[]" for descriptions instead of // not including it in the response. if (descriptions.length() == 0) { descriptions = null; } } return new SuggestionsCursor(suggestions, descriptions); } catch (JSONException e) { Log.w(TAG, "Error", e); } return null; } /** * Executes a GET request and returns the response content. * * @param urlString Request URI. * @return The response content. This is the empty string if the response * contained no content. */ public String readUrl(String urlString) { try { URL url = new URL(urlString); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); urlConnection.setRequestProperty("User-Agent", USER_AGENT); urlConnection.setConnectTimeout(HTTP_TIMEOUT_MS); if (urlConnection.getResponseCode() == 200) { final Charset responseCharset; try { responseCharset = ResponseUtils.responseCharset(urlConnection.getContentType()); } catch (UnsupportedCharsetException ucse) { Log.i(TAG, "Unsupported response charset", ucse); return null; } catch (IllegalCharsetNameException icne) { Log.i(TAG, "Illegal response charset", icne); return null; } byte[] responseBytes = Streams.readFully(urlConnection.getInputStream()); return new String(responseBytes, responseCharset); } else { Log.i(TAG, "Suggestion request failed"); return null; } } catch (IOException e) { Log.w(TAG, "Error", e); return null; } } public boolean supportsSuggestions() { return mSearchEngineInfo.supportsSuggestions(); } public void close() { } private boolean isNetworkConnected(Context context) { NetworkInfo networkInfo = getActiveNetworkInfo(context); return networkInfo != null && networkInfo.isConnected(); } private NetworkInfo getActiveNetworkInfo(Context context) { ConnectivityManager connectivity = (ConnectivityManager) context .getSystemService(Context.CONNECTIVITY_SERVICE); if (connectivity == null) { return null; } return connectivity.getActiveNetworkInfo(); } private static class SuggestionsCursor extends AbstractCursor { private final JSONArray mSuggestions; private final JSONArray mDescriptions; public SuggestionsCursor(JSONArray suggestions, JSONArray descriptions) { mSuggestions = suggestions; mDescriptions = descriptions; } @Override public int getCount() { return mSuggestions.length(); } @Override public String[] getColumnNames() { return (mDescriptions != null ? COLUMNS : COLUMNS_WITHOUT_DESCRIPTION); } @Override public String getString(int column) { if (mPos != -1) { if ((column == COLUMN_INDEX_QUERY) || (column == COLUMN_INDEX_TEXT_1)) { try { return mSuggestions.getString(mPos); } catch (JSONException e) { Log.w(TAG, "Error", e); } } else if (column == COLUMN_INDEX_TEXT_2) { try { return mDescriptions.getString(mPos); } catch (JSONException e) { Log.w(TAG, "Error", e); } } else if (column == COLUMN_INDEX_ICON) { return String.valueOf(R.drawable.magnifying_glass); } } return null; } @Override public double getDouble(int column) { throw new UnsupportedOperationException(); } @Override public float getFloat(int column) { throw new UnsupportedOperationException(); } @Override public int getInt(int column) { throw new UnsupportedOperationException(); } @Override public long getLong(int column) { if (column == COLUMN_INDEX_ID) { return mPos; // use row# as the _Id } throw new UnsupportedOperationException(); } @Override public short getShort(int column) { throw new UnsupportedOperationException(); } @Override public boolean isNull(int column) { throw new UnsupportedOperationException(); } } @Override public String toString() { return "OpenSearchSearchEngine{" + mSearchEngineInfo + "}"; } @Override public boolean wantsEmptyQuery() { return false; } }