Java tutorial
/** * Original Author: Shwetha Mallya, Minxuan Guo * * Copyright (C) 2014 INF 385T MAMA Project * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package com.project.android.dpla.mama_dpla; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.util.Log; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.StatusLine; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONObject; import org.json.JSONArray; import org.json.JSONException; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import java.net.UnknownHostException; import java.util.ArrayList; /** * Class: DataManager * Singleton class for interacting with DPLA as well as local db */ public class DataManager { /* Variable Declarations */ private static DataManager sInstance_ = null; // Tag for log files private static final String TAG = "MAMA_DPLA/DataManager"; // JSON node names private static final String TAG_DOCS = "docs"; private static final String TAG_TITLE = "sourceResource.title"; private static final String TAG_URL = "isShownAt"; private static final String TAG_PROVIDER = "dataProvider"; private static final String TAG_COLLECTION = "sourceResource.collection.title"; private static final String TAG_ID = "@id"; private static final String TAG_TYPE = "sourceResource.type"; private static final String APIKEY = "606d14833afd79665413f72a981fe811"; public String error_code = ReturnStatus.SUCCESS; private ArrayList<DPLAItem> mItems_ = null; public JSONArray docs = null; /* Member Function Definitions */ protected DataManager() { // to defeat instantiation } public static DataManager getInstance() { if (sInstance_ == null) { sInstance_ = new DataManager(); } return sInstance_; } /** * Fill in variable mItems_ with item info from DPLA and tags info from local db * @param keyword : User-typed searching keyword * @param activityContext : context of the activity that calls this function * @return error_code : the reason of exceptions. If successfully fetch data, return ReturnStatus.Success */ public String getSearchResultsWithTags(String keyword, Context activityContext) { String returnStatus = doSearch(keyword, activityContext); if (returnStatus == ReturnStatus.SUCCESS) updateResultsWithTags(activityContext); return returnStatus; } /** * Complete variable mItems_ with tags by accessing local db * Called by getSearchResultsWithTags (String keyword, Context activityContext) * @param activityContext : context of the activity that calls this function */ public void updateResultsWithTags(Context activityContext) { int items_len = mItems_.size(); // Open database for read MAMADbHelper helper = new MAMADbHelper(activityContext); SQLiteDatabase db = helper.getReadableDatabase(); // iterate mItems_ arraylist to fill each item for (int iter = 0; iter < items_len; iter++) { DPLAItem curr_item = mItems_.get(iter); String selection = MAMAContract.ItemEntry.COLUMN_NAME_ITEMATID + " = ?"; String[] selectionArgs = { curr_item.getId() }; Cursor cur = db.query(MAMAContract.ItemEntry.TABLE_NAME, MAMAContract.ItemEntry.ALL_COLUMS, selection, selectionArgs, null, null, null); if (cur.getCount() == 0) { // If there are no tags, set null curr_item.setTags(null); } else { cur.moveToFirst(); curr_item.setTags(cur.getString(MAMAContract.ItemEntry.TAG_COLUMN_NUMBER)); Log.d(TAG, curr_item.getTags()); } } } // end of updateResultsWithTags() /** * Perform the search using DPLA api based on a keyword and store results in mItems_ * Called by getSearchResultsWithTags (String keyword, Context activityContext) * @param keyword : User-typed searching keyword * @param activityContext : context of the activity that calls this function * @return error_code : the reason of exceptions. If successfully fetch data, return ReturnStatus.Success */ private String doSearch(String keyword, Context activityContext) { error_code = ReturnStatus.SUCCESS; try { // Format Searching URL String SERVER_URL = String.format("http://api.dp.la/v2/items?q=%s&%s", keyword, "&fields=sourceResource.title,@id,dataProvider,sourceResource.collection.title," + "isShownAt,sourceResource.type&api_key=" + APIKEY); // Request with POST method and check the status code HttpClient client = new DefaultHttpClient(); HttpGet post = new HttpGet(SERVER_URL); HttpResponse response = client.execute(post); StatusLine statusLine = response.getStatusLine(); //Clear mItems_ mItems_ = null; // Fetch and decode data if (statusLine.getStatusCode() == 200) { HttpEntity entity = response.getEntity(); InputStream content = entity.getContent(); Log.v(TAG, "success!"); // Success tag for successful connection to the dpla BufferedReader streamReader = new BufferedReader(new InputStreamReader(content, "UTF-8")); StringBuilder responseStrBuilder = new StringBuilder(); String contentString; while ((contentString = streamReader.readLine()) != null) responseStrBuilder.append(contentString); String json_string = responseStrBuilder.toString(); if (json_string != null) { try { JSONObject jsonObj = new JSONObject(json_string); // Getting JSON Array node docs = jsonObj.getJSONArray(TAG_DOCS); mItems_ = new ArrayList<DPLAItem>(); // Iterate on docs, Parsing JSON objects one by one for (int iter = 0; iter < docs.length(); iter++) { JSONObject dplaFromWeb = docs.getJSONObject(iter); if (dplaFromWeb.has(TAG_URL) && dplaFromWeb.has(TAG_ID)) { // NOTE: we do not handle DPLA items which do not have a url or @id String collection_title = null; if (dplaFromWeb.has(TAG_COLLECTION)) { // stripe all special symbols in collection title collection_title = dplaFromWeb.getString(TAG_COLLECTION).replaceAll("[^\\w\\s]", ""); } String item_title = dplaFromWeb.getString(TAG_TITLE).replaceAll("[^\\w\\s]", ""); String item_type = null; if (dplaFromWeb.has(TAG_TYPE)) { item_type = dplaFromWeb.getString(TAG_TYPE).replaceAll("[^\\w\\s]", ""); //sourceResource.type } //Considering 'data provider' is not NULL as mentioned by DPLA String item_data_provider = dplaFromWeb.getString(TAG_PROVIDER) .replaceAll("[^\\w\\s]", ""); DPLAItem di = new DPLAItem(dplaFromWeb.getString(TAG_ID), item_title, item_data_provider, dplaFromWeb.getString(TAG_URL), collection_title, item_type); mItems_.add(di); } } } catch (JSONException json_exp) { error_code = ReturnStatus.JSONFAIL; } } } else { Log.e(TAG, "Server responded with status code: " + statusLine.getStatusCode()); } } catch (UnknownHostException ex) { error_code = ReturnStatus.HTTPFAIL; } catch (UnsupportedEncodingException ex) { error_code = ReturnStatus.HTTPFAIL; } catch (ClientProtocolException ex) { error_code = ReturnStatus.HTTPFAIL; } catch (IOException ex) { error_code = ReturnStatus.HTTPFAIL; } return error_code; } public ArrayList<DPLAItem> getSearchResults() { return mItems_; // Returning the previously searched results here } }