org.sociotech.communitymashup.source.languagedetection.apiwrapper.DetectLanguageAPIWrapper.java Source code

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Here is the source code for org.sociotech.communitymashup.source.languagedetection.apiwrapper.DetectLanguageAPIWrapper.java

Source

/*******************************************************************************
 * Copyright (c) 2013 Peter Lachenmaier - Cooperation Systems Center Munich (CSCM).
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Peter Lachenmaier - Design and initial implementation
 ******************************************************************************/
package org.sociotech.communitymashup.source.languagedetection.apiwrapper;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.sociotech.communitymashup.source.languagedetection.apiwrapper.elements.Data;
import org.sociotech.communitymashup.source.languagedetection.apiwrapper.elements.Detection;
import org.sociotech.communitymashup.source.languagedetection.apiwrapper.elements.DetectionResult;

import com.google.gson.FieldNamingPolicy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;

public class DetectLanguageAPIWrapper {

    /** The parser. */
    private final JsonParser parser = new JsonParser();

    /**
     * Local reference to the api key. 
     */
    private String apiKey = null;

    /**
     * URL of the detectlanguage.com api
     */
    private static final String API_SERVICE_URL = "http://ws.detectlanguage.com/0.2/detect";
    private static final String API_QUERRY_ATTRIBUTE = "q";
    private static final String API_KEY_ATTRIBUTE = "key";

    /**
     * Constructs a new api wrapper for the given api key.
     * @param apiKey
     */
    public DetectLanguageAPIWrapper(String apiKey) {
        this.apiKey = apiKey;
    }

    /**
     * @param text
     * @return
     */
    public String detectMostConfidentLanguageString(String text) {
        Detection detection = detectMostConfidentLanguage(text);

        if (detection == null) {
            return null;
        }

        return detection.getLanguage();
    }

    /**
     * @param text
     * @return
     */
    public Detection detectMostConfidentLanguage(String text) {
        Data data = detectLanguage(text);

        if (data == null) {
            return null;
        }

        float highestConfidence = 0.0f;
        Detection result = null;

        // find best
        for (Detection detection : data.getDetections()) {
            if (detection.getConfidence() > highestConfidence) {
                highestConfidence = detection.getConfidence();
                result = detection;
            }
        }

        return result;
    }

    /**
     * @param text
     * @return
     */
    public Data detectLanguage(String text) {
        if (text == null || text.isEmpty()) {
            return null;
        }

        String result = null;

        //      // call service
        //      try {
        //         result = doGet(API_SERVICE_URL + "?" + API_QUERRY_ATTRIBUTE + "=" + URLEncoder.encode(text, "UTF-8") + "&" + API_KEY_ATTRIBUTE + "=" + apiKey);
        //      } catch (UnsupportedEncodingException e) {
        //         // malformed text
        //         return null;
        //      }

        Map<String, String> parameterMap = new HashMap<String, String>();

        try {
            parameterMap.put(API_QUERRY_ATTRIBUTE, URLEncoder.encode(text, "UTF-8"));
        } catch (UnsupportedEncodingException e) {
            // malformed text
            return null;
        }
        parameterMap.put(API_KEY_ATTRIBUTE, apiKey);

        // send post
        result = doPost(API_SERVICE_URL, parameterMap);

        if (result == null) {
            return null;
        }

        // parse result
        JsonElement json = parser.parse(result);

        // unmarshall the json
        DetectionResult resultObject = unmarshall(DetectionResult.class, json);

        return resultObject.getData();
    }

    private String doPost(String url, Map<String, String> parameterMap) {
        String result = null;

        HttpClient httpClient = new DefaultHttpClient();

        HttpPost post = new HttpPost(url);

        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);

        // add all post parameter
        for (String key : parameterMap.keySet()) {
            nameValuePairs.add(new BasicNameValuePair(key, parameterMap.get(key)));
        }

        ResponseHandler<String> responseHandler = new BasicResponseHandler();

        try {
            post.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            result = httpClient.execute(post, responseHandler);
        } catch (Exception e) {
            // do nothing
        } finally {
            // client is no longer needed
            httpClient.getConnectionManager().shutdown();
        }

        return result;
    }

    /**
     * Unmarshalls given json content of the given type.
     * 
     * @param type The result Type
     * @param json Json to be unmarshalled
     * 
     * @return Unmarshalled json content as object of the given type
     */
    protected <T> T unmarshall(Class<T> type, JsonElement json) {
        Gson gson = getGsonBuilder().create();
        return gson.fromJson(json, type);
    }

    /**
     * Unmarshalls given json content as a list of the given type.
     *  
     * @param type The result Type
     * @param json Json to be unmarshalled
     * 
     * @return Unmarshalled json content as list of objects of the given type
     */
    protected <T> List<T> unmarshallList(Class<T> type, JsonElement json) {
        List<T> retValue = new LinkedList<T>();
        if (json.isJsonArray()) {
            for (JsonElement element : json.getAsJsonArray()) {
                retValue.add(unmarshall(type, element));
            }
        }
        return retValue;
    }

    /**
     * Gets the gson builder.
     * 
     * @return the gson builder
     */
    protected GsonBuilder getGsonBuilder() {
        GsonBuilder builder = new GsonBuilder();

        //builder.setDateFormat(ApplicationConstants.DATE_FORMAT);
        builder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES);

        return builder;
    }
}